Showing papers on "Sowing published in 2005"
TL;DR: The incorporation of advanced molecular biology techniques in seed research is vital to the understanding and integration of multiple metabolic processes that can lead to enhanced seed germination, and consequently to improved stand establishment and crop yield under saline and non‐saline conditions.
Abstract: Rapid seed germination and stand establishment are critical factors to crop production under salt‐stress conditions. In many crop species, seed germination and early seedling growth are the most sensitive stages to salinity stress. Salinity may delay the onset, reduce the rate, and increase the dispersion of germination events, leading to reductions in plant growth and final crop yield. The adverse effects of salt‐stress can be alleviated by various measures, including seed priming (a.k.a. pre‐sowing seed treatment). The general purpose of seed priming is to partially hydrate the seed to a point where germination processes are begun but not completed. Most priming treatments involve imbibing seed with restricted amounts of water to allow sufficient hydration and advancement of metabolic processes but preventing germination or loss of desiccation tolerance. Treated seeds are usually redried before use, but they would exhibit rapid germination when re‐imbibed under normal or stress conditions. Various seed priming techniques have been developed, including hydropriming (soaking in water), halopriming (soaking in inorganic salt solutions), osmopriming (soaking in solutions of different organic osmotica), thermopriming (treatment of seed with low or high temperatures), solid matrix priming (treatment of seed with solid matrices), and biopriming (hydration using biological compounds). Each treatment has advantages and disadvantages and may have varying effects depending upon plant species, stage of plant development, concentration/dose of priming agent, and incubation period. In this article, we review, evaluate, and compare effects of various methods of seed priming in improving germination of different plant species under saline and non‐saline conditions. We also discuss the known metabolic and ultra‐structural changes that occur during seed priming and subsequent germination. To maximize the utility of various seed priming techniques, factors affecting their efficiency must be examined and potential benefits and drawbacks determined. For example, quality of the seed before treatment, concentration/dose of priming agent, time period for priming, and storage quality of the seed following priming treatment must be carefully determined. Furthermore, such assessments must be based on large‐scale experiments if seed priming is to be used for large‐scale field planting. A better understanding of the metabolic events that take place in the seed during priming and subsequent germination will improve the effective application of this technology. The incorporation of advanced molecular biology techniques in seed research is vital to the understanding and integration of multiple metabolic processes that can lead to enhanced seed germination, and consequently to improved stand establishment and crop yield under saline and non‐saline conditions.
772 citations
TL;DR: In this article, a 3-year field experiment in rainfed Vertisol was designed to study the effects of timing and splitting of N fertilizer on the efficiency of nitrogen in wheat (Triticum aestivum L.).
267 citations
TL;DR: The results demonstrate that seed size influences performance within and among species in part because of indirect effects of initial seedling size and suggest that traits tightly correlated with seed mass at the species level, such as specific leaf area, leaf longevity and photosynthetic capacity, may also contribute to interspecific performance differences.
Abstract: 1- We examined among- and within-species effects of seed mass for seedling establishment from seed to 5 years of age in a field experiment at Paracou, French Guiana. 2- Six seeds of each of eight species were weighed and planted into each of 120 plots (1 m2) throughout closed-canopy forest along 12 100-m transects in 1998. 3- We described the microhabitat of each planting site using principal components derived from measurements of light availability, soil moisture, carbon and nitrogen content, and soil phosphorus availability. Although both survival and relative growth rate (RGR) increased with increasing light availability, no other microhabitat variable significantly affected seedling performance. Nor did the magnitude of microhabitat effects on survival or RGR differ among species. 4- Larger-seeded species were more likely to survive from germination to 1 year as well as from 1 to 5 years of age. RGR for seedling height during the first year post-germination was not related to seed mass, but smaller-seeded species did grow slightly faster thereafter. Path analyses revealed that correlations between seed mass and performance were explained in part because larger seeds produced larger initial seedlings, which tended to survive better but grow more slowly. 5- We also analysed within-species effects of seed mass for the larger-seeded Eperua grandiflora and Vouacapoua americana (both Caesalpiniaceae). Larger seeds produced larger seedlings in both species, but larger seeds survived better only for Eperua. Larger seedlings grew more slowly in both species, but did not offset the early (Eperua) and later (Vouacapoua) positive direct effects of seed mass on RGR that may represent contrasting strategies for reserve deployment. 6- Our results demonstrate that seed size influences performance within and among species in part because of indirect effects of initial seedling size. However, we suggest that traits tightly correlated with seed mass at the species level, such as specific leaf area, leaf longevity and photosynthetic capacity, may also contribute to interspecific performance differences.
166 citations
TL;DR: In this article, a field experiment was conducted at the research farm of the Wheat Research Centre, Dinajpur, Bangladesh, for two consecutive years to evaluate rice straw as mulch, and to determine the optimum application rate of nitrogen (N) for no-till wheat.
160 citations
TL;DR: Performance was slightly better in seeds subjected to hardening for 24 h than the traditional soaking because of lower T50 and non-reducing sugars and higher reducing and total sugars and α-amylase activity, but in seed performance was impaired possibly because of KNO3 toxicity.
Abstract: The effects of pre-sowing seed treatments on the germination and emergence of fine rice and on reducing, nonreducing and total sugars and α-amylase activity were studied. Fine rice seeds were either soaked in tap water by a traditional method, hardened for 18 or 24 h (two cycles) or osmoconditioned (-1.1 MPa KNO3) for 24 or 48 h. Seed hardening (24 h) and the traditional soaking treatments resulted in a higher germination percentage, germination index and energy of germination and lower mean germination time and mean emergence time. Performance was slightly better in seeds subjected to hardening for 24 h than the traditional soaking because of lower T50 and non-reducing sugars and higher reducing and total sugars and α-amylase activity. In seeds subjected to osmoconditioning for 48 h seed performance was impaired possibly because of KNO3 toxicity.
160 citations
TL;DR: In this paper, the effect of legume termination date (using four legume species) on available soil water content at winter wheat planting and subsequent wheat yield in a semiarid environment was investigated.
Abstract: and yields were compared with wheat yields from conventional till other studies wheat yields following the green fallow wheat–fallow. Generally there were no significant differences in available soil water at wheat planting due to legume type. Soil water at period have been decreased due to lower soil water wheat planting was reduced by 55 mm when legumes were terminated content at wheat planting (Zentner et al., 1996; Schlegel early and by 104 mm when legumes were terminated late, compared and Havlin, 1997) or due to N deficiency (Pikul et al., with soil water in fallowed plots that were conventionally tilled. Aver- 1997). Under the higher temperature, higher evaporaage wheat yield was linearly correlated with average available soil tive demand environmental conditions of the central water at wheat planting, with the relationship varying from year to Great Plains, the positive economic trade-off between year depending on evaporative demand and precipitation in April, water used by the legumes and their favorable rotation May, and June. The cost in water use by legumes and subsequent and N fixing effects have not been observed (Vigil and decrease in wheat yield may be too great to justify use of legumes as Nielsen, 1998). The objectives of this study were (i) to fallow cover crops in wheat–fallow systems in semiarid environments. determine the effect of legume termination date (using four legume species) on available soil water content at winter wheat planting and subsequent wheat yield in a
155 citations
TL;DR: A series of field experiments was carried out to compare soil fertilization and micronutrient seed priming as methods of improving Zn and B nutrition of each crop and found that priming chickpea seeds failed to emerge at either site, causing complete yield loss, but this negative effect was not observed in the second season.
Abstract: Soil deficiencies of zinc (Zn) and boron (B) limit crop production in Nepal. Improving the micronutrient status of plants would increase yield and increase micronutrient content of the seeds, leading to better nutrition of the progeny crop and to improved human micronutrient nutrition. The primary micronutrient problem in grain legumes is B deficiency, while in rice (Oryza sativa), Zn deficiency is more important, and wheat (Triticum aestivum) suffers from both deficiencies. A series of field experiments was carried out over two seasons to compare soil fertilization and micronutrient seed priming as methods of improving Zn and B nutrition of each crop. Micronutrient treatments were evaluated for their effect on grain yield and grain micronutrient content. Soil B fertilization increased B content of the grain of lentil (Lens culinaris), chickpea (Cicer arietinum), and wheat by a factor of two to five, while increasing the yield of chickpea only. Soil fertilization with Zn had no effect on yield of any crop, but resulted in a small increase in Zn in wheat grain. Sowing micronutrient-primed seeds had no effect on yield or micronutrient content of the progeny seeds in most cases. During the first season, the primed chickpea seeds failed to emerge at either site, causing complete yield loss, but this negative effect was not observed in the second season with similar priming treatments at nearby sites, and no effect of priming on yield was observed with any other crop in either season.
152 citations
TL;DR: The effect of the Bt maize was small and within the normal variation expected in these agricultural systems, with one occurrence of CLPP varying between maize cultivars (Bt versus a conventional cultivar).
Abstract: Field trials were established at three European sites (Denmark, Eastern France, South-West France) of genetically modified maize (Zea mays L.) expressing the CryIAb Bacillus thuringiensis toxin (Bt), the near-isogenic non-Bt cultivar, another conventional maize cultivar and grass. Soil from Denmark was sampled at sowing (May) and harvest (October) over two years (2002, 2003); from E France at harvest 2002, sowing and harvest 2003; and from SW France at sowing and harvest 2003. Samples were analysed for microbial community structure (2003 samples only) by community-level physiological-profiling (CLPP) and phospholipid fatty acid analysis (PLFA), and protozoa and nematodes in all samples. Individual differences within a site resulted from: greater nematode numbers under grass than maize on three occasions; different nematode populations under the conventional maize cultivars once; and two occasions when there was a reduced protozoan population under Bt maize compared to non-Bt maize. Microbial community structure within the sites only varied with grass compared to maize, with one occurrence of CLPP varying between maize cultivars (Bt versus a conventional cultivar). An overall comparison of Bt versus non-Bt maize across all three sites only revealed differences for nematodes, with a smaller population under the Bt maize. Nematode community structure was different at each site and the Bt effect was not confined to specific nematode taxa. The effect of the Bt maize was small and within the normal variation expected in these agricultural systems.
135 citations
TL;DR: E enzymes of sucrose metabolism play an important role in increasing the yield of chickpea crops raised from primed seeds, and increased activities of SS and sucrose phosphate synthase (SPS) were observed in seeds of primed plants.
Abstract: The number of seeds and seed yield per plant were higher in chickpea crops raised from water and mannitol (4 %) primed seeds in comparison with the control non-primed crops. In primed plants, an enhanced acid invertase activity in the apical part of the main stem and the part immediately below it at 100 and 130 days after sowing (DAS) might result in an increased availability of hexoses to these plant parts. In addition, decreased acid invertase activity at the point of initiation of branches and in the internodes of stem observed in primed plants indicated restricted hydrolysis of sucrose during its transport through the stem, resulting in its more supply to the actively growing sinks. The activities of sucrose-cleaving enzymes, i.e. invertase and sucrose synthase (SS) in podwall of primed plants were higher at 110 DAS. At 140 DAS, a stage of rapid seed filling, increased activities of SS and sucrose phosphate synthase (SPS) were observed in seeds of primed plants. Increased SPS activity in seeds of primed crop could meet the increased assimilate requirements of the developing seeds. Higher activity of SS in seeds of primed crop may facilitate seed filling. These data suggest that enzymes of sucrose metabolism play an important role in increasing the yield of chickpea crops raised from primed seeds.
132 citations
TL;DR: Investigation of the effects of the density and spatial arrangement of spring wheat on weed biomass and wheat yield in weed-infested fields suggests that a very high degree of spatial uniformity may not be necessary to achieve a major increase in weed suppression by cereal crops.
Abstract: Summary It has been hypothesized that increased crop density and spatial uniformity can increase weed suppression and thereby play a role in weed management. Field experiments were performed over 2 years to investigate the effects of the density and spatial arrangement of spring wheat (Triticum aestivum) on weed biomass and wheat yield in weed-infested fields. We used three crop spatial patterns (normal rows, random and uniform) and three densities (204, 449 and 721 seeds m )2 ), plus a fourth density (1000 seeds m )2 ) in the random pattern. Increased crop density reduced weed biomass in all three patterns. Weed biomass was lower and crop biomass higher in wheat sown in the random and uniform patterns than in normal rows in both years. At 449 seeds m )2 , weed biomass was 38% lower in the uniform and 27% lower in the random pattern than in rows. There was evidence of decreasing grain yield due to intraspecific competition only at 1000 seeds m )2 . The results not only confirm that increasing density and increasing crop spatial uniformity increase the suppression of weeds, but also suggest that a very high degree of spatial uniformity may not be necessary to achieve a major increase in weed suppression by cereal crops. Rows represent a very high degree of spatial aggregation. Decreasing this aggregation increased weed suppression almost as much as sowing the crop in a highly uniform spatial pattern. While the random pattern produced as much crop biomass and suppressed weeds almost as well as the uniform pattern, the uniform pattern gave the highest yield.
124 citations
TL;DR: Number of stems per plant appears to be the most influential factor, although further research is required to confirm this and it is not wholly clear to which component of yield this should really be ascribed.
TL;DR: The results suggest that the legume/oats mix could exacerbate weed problems in subsequent vegetable crops and was affected by early-season canopy development and was highly correlated with cover crop plant density.
Abstract: Winter cover crops are increasingly common on organic and conventional vegetable farms on the central coast of California between periods of intensive vegetable production. A 2-yr study was conducted in Salinas, California, to quantify (1) cover crop and weed biomass production during cover cropping, (2) early-season canopy development of cover crops, (3) weed seed production by burning nettle during cover cropping, and (4) weed emergence following cover crop incorporation. The cover crops included oats, a mustard mix, and a legume/oats mix that were planted in October and soil-incorporated in February. Weed and cover crop densities, early-season cover crop canopy development, above-ground weed and cover crop biomass production, seed production by the burning nettle, and postincorporation weed emergence was evaluated. Mustard produced more early-season biomass than oats and the legume/oats mix. There were no differences in above ground biomass production by the cover crops at the end of their growth period. Suppression of weed biomass and seed production of burning nettle was greatest in mustard, and least in oats and the legume/oats mix. The weed suppressive ability of each cover crop was affected by early-season canopy development and was highly correlated with cover crop plant density. Weed emergence following cover crop incorporation was in order of legume/oats mix . oats . mustard in yr 1, but was not different in yr 2. This study provides initial information on cover crop effects on weed management in irrigated and tilled vegetable production systems in the central coast of California. The results suggest that the legume/oats mix could exacerbate weed problems in subsequent vegetable crops. Nomenclature: Burning nettle, Urtica urens L. # 3 URTUR; bell beans, Vicia faba L.; common vetch, Vicia sativa L.; lana vetch, Vicia villosa ssp. dasycarpa Roth; mustards, Brassica juncea (L.) Czern., Brassica hirta Moench; oats, Avena sativa L.; peas, Pisum sativum L. Additional index words: biomass production, canopy development, weed seed production, weed- suppressive ability. Abbreviations: DAI, days after incorporation; DAP, days after planting.
TL;DR: In this paper, the effect of various levels of water and N application through drip irrigation on seed cotton yield and water use efficiency was evaluated in two methods of planting (normal sowing and paired sowing).
01 Jan 2005
TL;DR: In this paper, 12 wheat genotypes were assessed for yield and quality parameters at two levels of sowing dates i.e., normal (18th November) and late sowing (11th December).
Abstract: Twelve wheat genotypes bred at this Institute were assessed for yield and quality parameters at two levels of sowing dates i.e., normal (18th November) and late sowing (11th December). The normal temperature persisted from December to February after which there was consistent rise in the temperature with heat shocks of 35 o C in the end of March. With delayed planting, the development of plant organs and transfer from source to sink were remarkably affected, which was reflected by overall shortening of plant height, reduction in number of internodes, days to heading, days to maturity and grain filling period and ultimately in the reduction of yield and yield components. The protein content of the genotypes was higher in late condition, possibly due to low grain weight. Genotypic responses were almost similar and in the same direction, however, the intensity varied.
TL;DR: Tropic Sunn' sunn-hemp has potential to be utilized as an alternative to winter legumes for ground cover and as an N source for a subsequent corn crop in the Southeast.
Abstract: The benefits of winter legumes as cover crops for corn (Zea mays L.) are diminished by the earliness of corn planting in relation to biomass and N production by the legumes. Tropical legumes may offer an alternative to winter legumes because they produce adequate biomass before corn planting. We determined the suitability of 'Tropic Sunn' sunn-hemp (Crotalaria juncea L.) as a cover crop for corn on a Compass loamy sand (coarse-loamy, siliceous, subactive, thermic Plinthic Paleudults) in central Alabama using a split-plot treatment structure in a randomized complete block design with four replications from 1991 to 1993. Main plots were winter fallow and sunn-hemp planted in mid-August, and subplots were N (0, 56, 112, and 168 kg N ha(-1)) applied to corn 3 weeks after planting (WAP). Sunn-hemp biomass production approximately 14 WAP (first frost) averaged 7.6 Mg ha(-1) with an N content of 144 kg ha(-1) in the first 2 yr of the study. Corn grain yield following sunn-hemp averaged 6.9 Mg ha(-1) whereas yield following winter fallow averaged 5.7 Mg ha(-1). Grain N averaged 16.3 kg ha(-1) greater for corn following sunn-hemp than fallow plots. Before first frost, sunn-hemp produced excellent biomass to serve as a winter cover crop in corn production while producing N equivalent to 58 kg ha(-1) of N fertilizer during the 3-yr period, based on corn yield and N response. Sunn-hemp has potential to be utilized as an alternative to winter legumes for ground cover and as an N source for a subsequent corn crop in the Southeast.
TL;DR: It was not possible to completely compensate for the detrimental influences of an unfavorable preceding crop on the grain yield of the subsequent wheat crop, and the Lemna bioassay suggested the presence of allelochemicals, which might have been one reason for the poor single plant development in autumn.
TL;DR: The yield of wheat lines containing the tin gene was 6% greater than their near-isogenic pairs where nitrogen status was high in the presence of terminal drought, whereas at lower grain protein sites it had a positive effect.
Abstract: Reduced tillering cereals have been proposed as being advantageous under terminal drought conditions through their reported reduction in non-productive tiller number and reduced soil water use prior to anthesis. This study was conducted to determine whether wheat (Triticum aestivum L.) lines containing the tiller inhibition (tin) gene have a yield penalty over their commercial near-isogenic counterparts. A terminal drought was experienced in all experiments. The effects of the tin gene were investigated in 4 different near-isogenic pairs of lines grown at 2 sowing densities at 4 locations in the eastern Australian wheatbelt over a 3-year period. Averaged over all experiments and lines, grain yield was unaffected by the presence of the tin gene. However, the highest yielding line contained the tin gene and its yield was 5% higher than all other lines. Averaged across the different genetic backgrounds, the tin gene decreased fertile spike number by 11%, increased the number of kernels/spike by 9%, and there was a 2% increase in kernel weight. The tin gene increased the harvest index by an average of 0.02, whereas above-ground biomass was reduced by 7%. Increasing sowing density from 50 to 100 kg/ha had little influence on yield or yield-related characteristics in both the restricted tillering and freely tillering lines. There was an interaction between sowing rate and the presence of the tin gene on yield, with tin lines yielding 0.2 t/ha more than the freely tillering lines at the higher sowing rate, whereas there was no effect at the lower sowing rate. The response of several lines containing the tin gene to nitrogen fertiliser was also investigated at 2 sites. Nitrogen increased spike number in all lines but the number remained around 20% less than in the freely tillering cultivars. The yield of wheat lines containing the tin gene was 6% greater than their near-isogenic pairs where nitrogen status was high in the presence of terminal drought. Grain protein concentration was unaffected by the presence of the tin gene at high grain protein sites, whereas at lower grain protein sites it had a positive effect.
TL;DR: In this paper, the influence of wheat canopy architecture on the partitioning of moisture between soil evaporation and crop transpiration, on a soil with high hydraulic conductivity, was investigated during the 1996-97 crop growth season at ICARDA in northern Syria.
Abstract: A study was conducted during the 1996–97 crop growth season at ICARDA in northern Syria, to investigate the influence of wheat canopy architecture on the partitioning of moisture between soil evaporation and crop transpiration, on a soil with high hydraulic conductivity. The study was conducted on the long-term two course wheat-lentil rotation trial, established on a swelling clay soil (Calcixerollic xerochrept). The wheat canopy architecture was manipulated by sowing the crop at either of two row-spacings, 0.17 or 0.30 m, both at a constant sowing rate equivalent to 120 kg ha−1. In this study, evapotranspiration from the crop was inferred from changes in soil moisture content over time, evaporation and rainfall interception were measured daily using microlysimetry, drainage was estimated as being the difference between potential daily evapotranspiration, and the evapotranspiration estimated from the soil water deficit. Between sowing and day 80 (tillering stage), evapotranspiration was calculated to consist mainly of soil evaporation. However, after day 80, transpiration became an increasingly dominant component of evapotranspiration. For both row-spacings, cumulative evapotranspiration over the season was approximately 373 mm. In the narrow-row crop, transpiration and soil evaporation were approximately 185 mm and 183 mm of water respectively. Conversely for the wide row-spaced crop, 172 mm of water was transpired while about 205 mm of water evaporated from the soil surface. While green leaf area index did not differ between row-spacings, the architecture of the crops as a result of sowing affected solar radiation penetration such that more incident radiation was intercepted at the soil surface of the wide row-spaced crop. This is likely to have made some contribution to the elevated levels of evaporation from the soil beneath the canopy of the wide-sown crop.
TL;DR: The results suggest that rye cover crops will not reduce corn yields if rye is killed 7 to 10 d before corn planting and if adequate N is applied, as well as postemergence weed control in the presence of rye mulch.
Abstract: A late-killed rye (Secale cereale L.) cover crop has many environmental benefits. However, rye can reduce following corn (Zea mays L.) yield and compromise pre-emergence herbicide activity. Our hypotheses were (i) rye reduces corn yields, especially if killed at late-boot stage; (ii) in-row tillage helps alleviate yield reductions; and (iii) postemergence weed control will be more effective than pre-emergence weed control in the presence of rye mulch. Corn was planted 7 to 10 d after rye was killed at early- and late-boot stage with no-till or zone-till. A no-rye control was included for comparison. Herbicide programs included half rate of pre-emergence herbicide, full rate of pre-emergence herbicide, and a postemergence herbicide. Rye biomass, soil bulk density, corn yield and population, and weed biomass were determined. Average rye biomass was 1400 kg ha -1 dry matter (DM) at early-boot stage and 4200 kg ha -1 DM at late-boot stage. In 2001, bulk density was reduced 0.08 Mg m -3 in the 0- to 10-cm depth in the late-killed rye plots compared with no rye or early killed rye. Rye never reduced no-till corn yields. Allelopathic effects of rye on corn were absent, calling for a better understanding of its underlying principles. Zone-till did not improve corn yields. Good weed control resulted from all herbicide programs due to low weed severity. The results suggest that rye cover crops will not reduce corn yields if rye is killed 7 to 10 d before corn planting and if adequate N is applied.
TL;DR: The results indicate that water is the primary source of seeds dispersing to the site and that a species-rich pool of dispersing propagules is present, an interesting result given the urbanized nature of the surrounding landscape.
Abstract: Although seed dispersal is assumed to be a major factor determining plant community development in restored wetlands, little research exists on density and species richness of seed available through dispersal in these systems. We measured composition and seed dispersal rates at a restored tidal freshwater marsh in Washington, DC, USA by collecting seed dispersing through water and wind. Seed dispersal by water was measured using two methods of seed collection: (1) stationary traps composed of coconut fiber mat along an elevation gradient bracketing the tidal range and (2) a floating surface trawl net attached to a boat. To estimate wind dispersal rates, we collected seed from stationary traps composed of coconut fiber mat positioned above marsh vegetation. We also collected a small number of samples of debris deposited along high tide lines (drift lines) and feces of Canada Goose to explore their seed content. We used the seedling emergence method to determine seed density in all samples, which involved placing the fiber mats or sample material on top of potting soil in a greenhouse misting room and enumerating emerging seedlings. Seedlings from a total of 125 plant species emerged, during this study (including 82 in river trawls, 89 in stationary water traps, 21 in drift lines, 39 in wind traps, and 10 in goose feces). The most abundant taxa includedBidens frondosa, Boehmeria cylindrica, Cyperus spp.,Eclipta prostrata, andLudwigia palustris. Total seedling density was significantly greater for the stationary water traps (212±30.6 seeds/m2/month) than the equal-sized stationary wind traps (18±6.0 seeds/m2/month). Lower-bound estimates of total species richness based on the non-parametric Chao 2 asymptotic estimators were greater for seeds in water (106±1.4 for stationary water traps and 104±5.5 for trawl samples) than for wind (54±6.4). Our results indicate that water is the primary source of seeds dispersing to the site and that a species-rich pool of dispersing propagules is present, an interesting result given the urbanized nature of the surrounding landscape. However, species composition of dispersing seeds differed from vegetation of restored and natural tidal freshwater marshes, indicating that planting is necessary for certain species. At other restoration sites, information on densities of dispersing seeds can support decisions on which species to plant.
TL;DR: Genetic variation for coleoptile length and availability of gibberellin-responsive dwarfing genes such as Rht8 will allow development of long coleOptile wheats for deep sowing or where stubble retention is practiced.
Abstract: Crop residues protect soils from erosion, reduce soil water evaporation and increase soil organic matter. Yet management of stubbles for cropping can be difficult. Surface-retained residue can act as a mechanical barrier to slow emergence and reduce seedling biomass. Longer coleoptiles improve seedling emergence with deep sowing and may assist where stubble load is large. In a glasshouse study, six wheat and barley genotypes were sown at 30 and 50 mm depth into pots containing pasteurised soil. Unweathered sorghum, canola and wheat stubble were added at 0, 3 and 6 t/ha equivalents to the soil surface and pots watered above or below the stubble. Stubble species and watering regime had little effect on seedling growth. However, deeper sowing and increased stubble mass adversely affected most seedling characteristics particularly slowing seedling emergence and reducing tiller number to decrease plant biomass (environmental correlations (re) of −0.98** and 0.88**, respectively). Shorter coleoptile Rht-B1b wheats ‘Banks’ and ‘Janz’, and barley ‘Beecher’ emerged slower and abnormally with thicker stubble, and had more sterile tillers to reduce total tiller number and biomass. Deeper crowns for these genotypes also resulted in proportionally less biomass located above the stubble. The converse was true of long coleoptile ‘Vigour 18’, ‘Halberd’, and its Rht8 progeny, ‘HM14bS’ which were less affected by stubble mass and sowing depth. In a corresponding field study, increasing wheat stubble mass from 0 to 3 and 6 t/ha delayed seedling emergence and decreased plant number to reduce biomass. Short coleoptile wheat genotypes ‘Hartog’ and ‘Janz’ emerged slower and produced less biomass at 3 and 6 t/ha of stubble than long coleoptile wheat genotypes ‘Halberd’ and ‘HM14bS’. Emergence of seedlings sown at 50 mm depth with 6 t/ha overlying stubble was similar to that sown at 120 mm with no stubble, reflecting the similar impact of retained residues to deep sowing. Genetic variation for coleoptile length and availability of gibberellin-responsive dwarfing genes such as Rht8 will allow development of long coleoptile wheats for deep sowing or where stubble retention is practiced.
TL;DR: The hypothesis that manipulating photoperiod sensitivity during post-flowering in indeterminate soybean may actually be an avenue to increase seed number and yield is strengthened.
TL;DR: The results show that restora- tion of degraded areas with P. australis is possible and that there is potential to improve restoration success with a careful selection of seed provenance and planting microsites.
Abstract: South American high-mountain ecosystems are greatly influenced by human disturbance. In the mountains of Cordoba, Argentina, Polylepis australis (Rosaceae) woodlands are currently highly fragmented and subject to extensive burning and livestock grazing, resulting in severe changes of habitat characteristics, which hamper natural regeneration. In order to find out how to achieve successful reforestation, we compared P. australis seed- ling survival and growth and the development of a shrubby habit for two seed provenances and different planting mi- crosites. Survival of planted seedlings after 5 years was 70%, with most deaths (19%) in the first year and declin- ing mortality with ongoing establishment. Survival did not show any relationship with seed provenance or microsite characteristics. Height growth averaged 34.6 ± 1.2 cm in 5 years. Seedlings produced from seeds collected in a well-preserved woodland grew taller and showed a higher tendency for development of shrubby habit than those produced from seeds collected in a degraded woodland. Seedlings planted in more degraded microsites with exposed soil or rock due to past grazing pressure grew less and developed a more shrubby habit than those planted in better preserved microsites. Our results show that restora- tion of degraded areas with P. australis is possible and that there is potential to improve restoration success with a careful selection of seed provenance and planting microsites.
01 Jan 2005
TL;DR: The study revealed that depulping the fruits and soaking 5 in water for various periods significantly enhanced seed germination and seedling growth of Horitoki, and pre- sowing treatment, T (depulped seeds soaking in cold water for 48 hours) was more effective in germination.
Abstract: 2 Abstract: The study was conducted over a period of six months from January to June 2004 to explore the effects of different seed treatments on germination and seedling growth attributes of a popular medicinal plant, Horitoki (Terminalia chebula Retz) in the nursery of Chittagong University, Bangladesh. Seeds were subjected to six pre-sowing treatments e.g. control (T ), depulped (T ), depulped and soaked in cold water for 12 hours (T ), 0 1 2 depulped and soaked in cold water for 24 hours (T ), depulped and soaked in cold water for 48 hours (T ) and 3 4 depulped and soaked in hot water for 2 minutes (T ). The study revealed that depulping the fruits and soaking 5 in water for various periods significantly enhanced seed germination and seedling growth. Seed germination started 29 days after sowing and continued up to 86 days. The highest germination percentage (66.7%) was observed in the fruit depulped and soaked in cold water for 48 hours (T ) followed by 60% in the depulped 4 seeds soaked in cold water for 24 hours (T ). The lowest germination percentage (48.9%) was obtained from 3 controlled seeds (T ). The highest germination value (4.41), germination energy (58.9) and vigor index (5291) 0 was also obtained in T , which was significantly (p<0.05) different from the control and other treatments. Shoot 4 length, root length, collar diameter and leaf number followed the same trend of higher value for T T and T 4, 5 3 respectively. Similar trend was also observed in shoot, root and total seedling dry weight. Therefore, pre- sowing treatment, T (depulped seeds soaking in cold water for 48 hours) was more effectivein germination and 4 production of quality seedling of T. chebula in the nursery.
TL;DR: A greater occupation of soil by the cultivated species, greater yield forage and greater amount of nutrients incorporated of this biomass were observed, without significantly affecting maize yield grain.
Abstract: The aim of this study was to evaluate the occurrence of weeds, nutritional state and yield of maize - B. brizantha intercrop under different layouts of Brachiaria pasture sowing treated with the herbicide mixture nicosulfuron + atrazine and atrazine. In the plots, the treatments consisted in maize and B. brizantha sowing in single crops, besides four forms of establishing B. brizantha by sowing one and two rows of B. brizantha in-between the maize rows; sowing along the same row as maize; and sowing the forage scattered in-between the maize rows. In the subplots, the two secondary treatments consisted in using the herbicide mixture nicosulfuron + atrazine (8 + 1,500 g ha-1) and atrazine (1,500 g ha-1) applied 30 days after emergence (DAE). Dry biomass of the macronutrient levels, grain yield and the weight of a thousand maize kernels, as well as the total dry matter yield and macronutrients accumulated by the pasture were evaluated. The weed species Brachiaria plantaginea, Brachiaria decumbens, and Sorghum arundinaceum were controlled by the mixture nicosulfuron + atrazine; the species Digitaria horizontalis, Cyperus rotundus, and Artemisia verlotorum were not controlled by the herbicide mixture. Lower levels of total chlorophyll and N leaf contents in maize were observed when two rows of B. brizantha were cultivated in-between the maize rows. When the herbicide mixture nicosulfuron + atrazine was used, highest levels of total chlorophyll, N, P, and K, grain yield, and weight of a thousand kernels were observed in maize compared to the treatments without product application. When two rows of B. brizantha were cultivated in-between the maize rows, a greater occupation of soil by the cultivated species, greater yield forage and greater amount of nutrients incorporated of this biomass were observed, without significantly affecting maize yield grain.
TL;DR: Pre-sowing magnetic treatments would appear to enhance the growth and yield of tomatoes cultivated late in the season.
Abstract: The effects of pre-sowing magnetic treatments on the growth and yield of tomatoes (cv. Vyta), cultivated late in the season, were studied under field conditions. Tomato seeds were exposed either to a 120 mT dynamic magnetic field (induced by an experimental electromagnet) for 10 min or to a 80 mT field for 5 min. Non-treated seeds were used as controls. Plants were grown in experimental plots (20.2 square m) and cultivated according to standard agriculture practices. At physiological maturity, the plants were harvested from each plot and the number of fruits, mean fruit weight, fruit yield per plant and fruit yield per area determined. In the nursery stage, the treatments led to a significant increase in root length, fresh and dry root weight, stem length, fresh and dry stem weight, leaf area and foliole dry weight. During the vegetative stage, the leaf, stem and root relative growth rates of plants derived from magnetically-treated seeds were greater than those shown by control plants. In the generative stage, the relative growth rate of the fruits belonging to the "magnetically treated plants" was greater than that of control plant fruits. At the fruit maturity stage, the magnetically treated seeds produced plants with significantly more fruits (17.9-21.3%), with a significantly greater mean fruit weight (22.3-25.5%), and with a greater fruit yield per plant (47.3-51.7%) and per area (48.6-50.8%) than did the control plants. Pre-sowing magnetic treatments would appear to enhance the growth and yield of tomatoes cultivated late in the season.
TL;DR: In this article, a diagnostic method for assessing regional variations in yield was implemented for a network of 24 organic wheat fields located in two neighboring regions, Diois and Val de Drome (France).
Abstract: A diagnostic method for assessing regional variations in yield was implemented for a network of 24 organic wheat fields located in two neighboring regions, Diois and Val de Drome (France). We studied: yield and its components; field environmental conditions of the fields; relations between indicators of potential limiting factors and yield components; and linkages between crop management and yield-limiting factors. The yield performances were low and variable (3.5 ± 1.4 t*ha-1). The relative kernel number (RKN) was significantly related to nitrogen nutrition and weed density at flowering. The nitrogen nutrition index (NNIf) had a strong and positive effect on relative kernel number, while weed density (1/WF) had a negative effect. The percentage of kernel number variation explained by the regression model (RKN = 0.112 + 0.609 × NNIf + 0.2 × 1/WF) was adequate (Adj. R2 = 0.53) with a RMSE of 0.09. The duration of the period of grain filling, reflected in the temperature sum, had a strong and positive effect on relative kernel weight (RTKW), while soil compaction and high temperature had a negative influence. Adjusted R2 for the model was 0.42 with a RMSE of 0.16. The results confirm that legumes preceding crops improve nitrogen nutrition on subsequent winter wheat, e.g. the Nitrogen Nutrition Index at flowering (NNIf) = 0.51 ± 0.12 for a crop rotation with a rate of legumes over 37% vs. 0.41 ± 0.11 for a crop rotation with a rate of legumes under 25%. Alfalfa preceding crops significantly limited the weed density at harvest while stony soils and early sowing (before November 1st) enhanced weed density.
TL;DR: It is concluded that an increased nutritional status of the plants lead to an increase in borer attacks at the early stage of plant growth, but also to improved plant vigour, resulting finally in a net benefit for the plant and grain yield.
TL;DR: Preliminary results from field experiments suggest that Rhizobium inoculation is very effective over and above the already demonstrated benefits of priming with water alone, and some primed crops show enhanced resistance to disease.
Abstract: On-farm seed priming with water is a low-cost, low-risk technology that is easily adopted by resource-poor farmers. It increases the yield of tropical and subtropical annual crops in marginal areas by a combination of better crop establishment and improved individual plant performance. The effects of seed priming, i.e. soaking seeds overnight in water before sowing, on plant growth and development are consequences of faster germination, emergence, and more vigorous early growth. Results from in-vitro, on-station and on-farm experiments are discussed. Recent work has tested opportunities for resource-poor farmers to use seed priming as a vehicle for applying biofertilisers (Rhizobia). Preliminary results from field experiments suggest that these interventions are very effective over and above the already demonstrated benefits of priming with water alone. In a pot experiment using chickpea, combining a Rhizobium inoculation with seed priming significantly increased nodulation but had little effect on yield. Nevertheless, the results confirmed that Rhizobium inoculation is compatible with on-farm seed priming. Observations in the field have shown that some primed crops show enhanced resistance to disease, either as a consequence of increased vigour, altered phenology, or due to some more fundamental mechanism associated with exposure of seeds to anaerobic conditions during priming. Priming seeds of a highly susceptible cultivar of pearl millet in water for 8 h before sowing significantly reduced the incidence of downy mildew in artificially infected seedlings from 80% to less than 60%.
Journal Article•
TL;DR: In this paper, a pre-sowing treatment of the pea sowing material with a magnetic field resulted in a significant increase in the seed yield, which resulted from a higher number of pods per plant and lower losses of plants from a surface unit during vegetation.
Abstract: Nowadays, when the rational usage of agricultural production space is promoted, the pre-sowing seed treatment with physical factors becomes more important. These factors, which are generally considered as harmless for the environment, most often modify the course of some physiological and biochemical processes in the seeds, increasing their vigour and ensuring better plant development at later stages. The magnetic field is especially worth our attention, since its impact on the seeds can change the course of some processes taking place in the seeds and so stimulates plant development. However, this issue can also be significant in the cultivation of leguminous plants as this group is characterised by low yields which vary considerably from year to year. The present study was carried out in the Institute of Soil Science and Plant Cultivation in Pu³awy, in the years 2000-2002. The factor of the 1st order were two varieties of the pea seeds, ie: Rola - a leafy type, and Piast - an afila type; whereas the factor of the 2nd order - 3 exposure doses of magnetic field: D0 - without laser treatment (control), D1 -1 0 750 J m -3 s( B =3 0 mT, s=1 5 s) andD2 -8 5 987 Jm -3 s( B =8 5 mT, s=1 5 s). Seed treatment was carried out in the Department of Physics of the University of Agriculture in Lublin. The study carried out proved a favourable influence of the magnetic treatment on the emergence, growth and development of both pea varieties. The pre-sowing treatment of the pea sowing material with a magnetic field resulted in a significant increase in the seed yield. The efficiency of the treatment applied depended on the variety, the exposure dose of the magnetic field and the course of weather conditions. The increase in the pea seed yield due to this treatment resulted from a higher number of pods per plant and lower losses of plants from a surface unit during vegetation.