Showing papers on "Sowing published in 2010"

Crop planting dates: an analysis of global patterns.

Abstract: Aim To assemble a data set of global crop planting and harvesting dates for 19 major crops, explore spatial relationships between planting date and climate for two of them, and compare our analysis with a review of the literature on factors that drive decisions on planting dates. Location Global. Methods We digitized and georeferenced existing data on crop planting and harvesting dates from six sources. We then examined relationships between planting dates and temperature, precipitation and potential evapotranspiration using 30-year average climatologies from the Climatic Research Unit, University of East Anglia (CRU CL 2.0). Results We present global planting date patterns for maize, spring wheat and winter wheat (our full, publicly available data set contains planting and harvesting dates for 19 major crops). Maize planting in the northern mid-latitudes generally occurs in April and May. Daily average air temperatures are usually c. 12–17 °C at the time of maize planting in these regions, although soil moisture often determines planting date more directly than does temperature. Maize planting dates vary more widely in tropical regions. Spring wheat is usually planted at cooler temperatures than maize, between c. 8 and 14 °C in temperate regions. Winter wheat is generally planted in September and October in the northern mid-latitudes. Main conclusions In temperate regions, spatial patterns of maize and spring wheat planting dates can be predicted reasonably well by assuming a fixed temperature at planting. However, planting dates in lower latitudes and planting dates of winter wheat are more difficult to predict from climate alone. In part this is because planting dates may be chosen to ensure a favourable climate during a critical growth stage, such as flowering, rather than to ensure an optimal climate early in the crop's growth. The lack of predictability is also due to the pervasive influence of technological and socio-economic factors on planting dates.

Soil microbial biomass and activity under different agricultural management systems in a semiarid Mediterranean agroecosystem

Abstract: A field experiment was carried out in a semiarid agricultural Mediterranean area located at the “El Teularet” experimental field in the Enguera Sierra (Valencia, southeast Spain) to assess the influence of different agricultural management systems on indicators of soil biological quality and activity (microbial biomass C, basal respiration, C mineralization coefficients, metabolic quotient (qCO2), respiratory quotient (RQ: moles CO2 evolved/moles O2 consumed), soluble C and dehydrogenase, urease, protease-BAA, phosphatase and β-glucosidase activities), one year after treatment establishment. The management practices assayed were as follows: application of the herbicides paraquat, glyphosate or oxyfluorfen, addition of olive tree pruning residues, ploughing, sowing of oats + addition of crop residues + ploughing, sowing of Medicago sativa, sowing of oats and vetch + addition of crop residues and addition of oat straw. A non-treated plot was used as control soil and a plot under natural vegetation was used as a standard of local, high quality soil. The plots with addition of oat straw had higher values of enzymatic activity, microbial biomass and respiration, reaching similar values to soil under native vegetation. The lowest levels of soil biological quality indicators were observed in the plots with application of some type of herbicide. Low RQ values were observed in these plots as consequence of the scarce-null inputs of organic matter, suggesting an increase in organic matter recalcitrance. The addition of oat straw to soil can be considered an effective technology, due to the rapid improvement of soil quality, for carrying out sustainable agriculture in semiarid Mediterranean agroecosystems.

Climate-driven simulation of global crop sowing dates

Abstract: Aim To simulate the sowing dates of 11 major annual crops at the global scale at high spatial resolution, based on climatic conditions and crop-specific temperature requirements. Location Global. Methods Sowing dates under rainfed conditions are simulated deterministically based on a set of rules depending on crop-and climate-specific characteristics. We assume that farmers base their timing of sowing on experiences with past precipitation and temperature conditions, with the intra-annual variability being especially important. The start of the growing period is assumed to be dependent either on the onset of the wet season or on the exceeding of a crop-specific temperature threshold for emergence. To validate our methodology, a global data set of observed monthly growing periods (MIRCA2000) is used. Results We show simulated sowing dates for 11 major field crops world-wide and give rules for determining their sowing dates in a specific climatic region. For all simulated crops, except for rapeseed and cassava, in at least 50% of the grid cells and on at least 60% of the cultivated area, the difference between simulated and observed sowing dates is less than 1 month. Deviations of more than 5 months occur in regions characterized by multiple-cropping systems, in tropical regions which, despite seasonality, have favourable conditions throughout the year, and in countries with large climatic gradients. Main conclusions Sowing dates under rainfed conditions for various annual crops can be satisfactorily estimated from climatic conditions for large parts of the earth. Our methodology is globally applicable, and therefore suitable for simulating sowing dates as input for crop growth models applied at the global scale and taking climate change into account.

Seed rain under tree islands planted to restore degraded lands in a tropical agricultural landscape.

Abstract: Planting native tree seedlings is the predominant restoration strategy for accelerating forest succession on degraded lands. Planting tree ''islands'' is less costly and labor intensive than establishing larger plantations and simulates the nucleation process of succession. Assessing the role of island size in attracting seed dispersers, the potential of islands to expand through enhanced seed deposition, and the effect of planting arrangements on seed dispersal by birds and bats informs restoration design. Determining the relative importance of local restoration approach vs. landscape-level factors (amount of surrounding forest cover) helps prioritize methods and locations for restoration. We tested how three restoration approaches affect the arrival of forest seeds at 11 experimental sites spread across a gradient of surrounding forest cover in a 100-km 2 area of southern Costa Rica. Each site had three 50 3 50 m treatments: (1) control (natural regeneration), (2) island (planting tree seedlings in patches of three sizes: 16 m 2 ,6 4 m 2 , and 144 m 2 ), and (3) plantation (planting entire area). Four tree species were used in planting (Terminalia amazonia, Vochysia guatemalensis, Erythrina poeppigiana, and Inga edulis). Seed rain was measured for 18 months beginning ;2 years after planting. Plantations received the most zoochorous tree seeds (266.1 6 64.5 seedsm � 2 � yr � 1 (mean 6 SE)), islands were intermediate (210.4 6 52.7 seedsm � 2 � yr � 1 ), and controls were lowest (87.1 6 13.9 seedsm � 2 � yr � 1 ). Greater tree seed deposition in the plantations was due to birds (0.51 6 0.18 seedsm � 2 � d � 1 ), not bats (0.07 6 0.03 seedsm � 2 � d � 1 ). Seed rain was primarily small- seeded, early-successional species. Large and medium islands received twice as many zoochorous tree seeds as small islands and areas away from island edges, suggesting there is a minimum island size necessary to increase seed deposition and that seed rain outside of planted areas is strongly reduced. Planting design was more important for seed deposition than amount of forest cover within the surrounding 100- and 500-m radius areas. Establishing plantations and large islands facilitates the arrival of early-successional tree seeds and represents a broadly applicable strategy for increasing seed rain on abandoned agricultural lands. However, more intensive restoration approaches may be necessary for establishment of dispersal-limited species.

Effect of maize (Zea mays L.) - cowpea (Vigna unguiculata L.) intercropping on light distribution, soil temperature and soil moisture in arid environment

Abstract: Sole crops and intercrops of maize (Zea mays L.) and cowpea (Vigna unguiculata L.) were studied at eight planting ratios of maize: cowpea (100:100, 50:100, 100:50, 25:75, 75:25, 50:50, 0:100 and 100:0 ) and two harvest times (milky stage and doughy stage). This experiment was carried during two years (2007 and 2008) on Research Center, University of Zabol, Iran, to investigate the influence of cowpea on the microclimate of their intercrop and sole maize (SM) as control. Measurements of photosynthetically active radiation (PAR), soil temperature (ST), soil moisture (SM) and crop yield were carried out to study the effects of intercropping on crop yield in a cowpea-maize intercropping system in Sistan at southeast of Iran. We found that intercropping increased the amount of absorption PAR compared to sole crop of maize. The highest amount of PAR was obtained at 100% cowpea + 100% maize with no significant difference to 100% cowpea + 50% maize. The lowest amount of PAR was obtained at 75% maize + 25% cowpea. Intercropping system had significant effects on soil temperature and soil moisture (P<0.01). The highest soil temperature was obtained at sole maize and the lowest temperature was at sole cowpea. Soil moisture was lowest at sole maize and highest at sole cowpea. LER (land equivalent ratio) values were greater in all intercropping systems with different planting ratios which indicated yield advantage of intercropping over sole cropping of maize. Results indicate that intercropping can increase light interception and increased shading in intercropping system compared to sole maize and reduce water evaporation and improve conservation of soil moisture. Based on high grain and suitable environmental condition, intercrop productivity compared to sole crop could be selected for improving the productivity of maize/cowpea mixture in the Southeast of Iran.

Cover-Crop Roller–Crimper Contributes to Weed Management in No-Till Soybean

Abstract: Termination of cover crops prior to no-till planting of soybean is typically accomplished with burndown herbicides. Recent advances in cover-crop roller–crimper design offer the possibility of reliable physical termination of cover crops without tillage. A field study within a no-till soybean production system was conducted in Urbana, IL, from 2004 through 2007 to quantify the effects of cover crop (cereal rye, hairy vetch, or bare soil control), termination method (chemical burndown or roller–crimper), and postemergence glyphosate application rate (0, 1.1, or 2.2 kg ae ha−1) on soybean yield components, weed–crop interference, and soil environmental variables. Biomass of weeds surviving management within a soybean crop following either a vetch or rye cover crop was reduced by 26 and 56%, respectively, in the rolled system compared to the burndown system. Soybean yield loss due to weed interference was unaffected by cover-crop termination method in soybean following a rye cover crop, but was high...

The longevity of crop seeds stored under ambient conditions.

Abstract: The ability of crop seeds to retain their viability over extended periods of uncontrolled temperature and/or relative humidity conditions has not been widely investigated, although this is an important issue for genebank management. We report here the response of 18 crop species to storage for up to 26 years at 20.3 ^ 2.38C and 50.5 ^ 6.3% relative humidity. Germination rates decreased in a sigmoid fashion, but the curve parameters were species characteristic. Pea, common bean and maize seeds retained their viability over the longest period (23, 21 and 19 years, respectively). In contrast, chive seeds survived for only 5 years and lettuce for 7 years. In addition to this interspecific variability, there were also indices for intraspecific variability, particularly in bean and chive seeds, just as in collard, lupin, poppy, wheat and maize seeds. A significant correlation was obtained between germination performance in the laboratory and seedling emergence following autumn sowing. Seeds in which oil was the major seed storage component were more short lived, whereas carbohydrates or proteins did not show an effect on seed longevity.

The role of intercropping maize ( Zea mays L.) and Cowpea ( Vigna unguiculata L.) on yield and soil chemical properties

Abstract: Farmers in Sistan region experience low crop yields of crops due to low soil fertility. Sole crops and intercrops of maize (Zea mays L.) and cowpea (Vigna unguiculata L.) were studied at eight planting ratios of maize: cowpea (100:100, 50:100, 100:50, 25:75, 75:25, 50:50, 0:100 and 100:0) and two harvest times (milky stage and doughy stage). This experiment was carried during two years (2007 and 2008) on Research Center, University of Zabol, Iran, to investigate the influence of cowpea on the soil fertility and sole maize (SM) as control. Measurements of nitrogen, phosphorous, potassium soil and crop yield were carried out to study the effects of intercropping on crop yield in a cowpea-maize intercropping system in Sistan at southeast of Iran. We found that intercropping increased the amount nitrogen (N), phosphorous (P) and potassium (K) contents compared to sole crop of maize. The highest amount of N, P, K in soil was obtained at sole cowpea and 100% cowpea + 100% maize with no significant difference to 100% cowpea + 50% maize. The lowest amount of N, P, and K was obtained at sole maize and 75% maize + 25% cowpea. Intercropping system had significant effects on soil fertility and crop yield. LER (land equivalent ratio) values were greater in all intercropping systems with different planting ratios which indicated yield advantage of intercropping over sole cropping of maize. Results indicate that intercropping can increase nutrient elements of soil compared to sole maize and improve conservation of soil fertility. Based on high grain and improve soil fertility intercrop productivity compared to sole crop could be selected for improving the productivity of maize/cowpea mixture in the Southeast of Iran. Key words: Intercropping system, maize - cowpea, soil fertility, land equivalent ratio.

Cheatgrass facilitates spillover of a seed bank pathogen onto native grass species

Abstract: Summary 1. Pathogen spillover occurs when disease levels for a given population are driven by transmission from a reservoir species that carries a high pathogen load. Pathogen spillover is widely documented in crop systems, but has been little studied in natural plant communities. 2. The abundant seed production of weedy species may create a scenario where spillover of a generalist seed pathogen onto less abundant seeds of native hosts is possible. The invasive annual weed cheatgrass (Bromus tectorum) is a potential reservoir species for Pyrenophora semeniperda, a multiple-host fungal seed pathogen that naturally occurs in the semi-arid western United States. 3. To investigate potential community-level consequences of spillover by this pathogen in plant communities invaded by cheatgrass, we first used artificial inoculation studies to determine the relative susceptibility of seeds of cheatgrass and five co-occurring native grasses to P. semeniperda. Secondly, we quantified the pathogen reservoir (density of pathogen-killed seeds) in the spring seed bank for cheatgrass monoculture, cheatgrass-invaded native grass, and uninvaded native grass patches. Thirdly, potential pathogen spillover onto co-occurring native grasses was quantified by planting native grass seeds into field-collected seed-zone samples from each vegetation patch type and scoring subsequent seed mortality. 4. All species tested were susceptible to infection by P. semeniperda, but their vulnerability to seed death varied as a function of germination time and degree of susceptibility. 5. Seed bank samples from cheatgrass-dominated patches contained seed densities over four times higher than samples from uninvaded native grass patches, and P. semeniperda-killed seeds were also present at much higher densities, indicating that cheatgrass can function as a reservoir for P. semeniperda. Native seeds planted into seed-zone samples from cheatgrass-dominated patches were more likely to be killed by P. semeniperda than those planted into samples from uninvaded native patches. Seed mortality also varied across years, sites and host species. 6. Synthesis. Pathogen spillover onto native seeds is likely to operate within seed banks of semi-arid communities invaded by cheatgrass, and perhaps other weeds, and may have broad consequences for community structure. Our findings also demonstrate the ecological significance of multiple-host pathosystems that operate at the seed stage.

Effects of bryophytes and grass litter on seedling emergence vary by vertical seed position and seed size

Abstract: Establishment of plants through seeds is often constrained by the quality of microsites, which is in part controlled by the nature and amount of ground cover. The latter consists of living shoots of vascular plants or bryophytes and/or the dead remains of the dominant species. In the present article, we report the results of a controlled pot experiment with five species characteristic of floodplain grasslands. We manipulated the amounts of grass litter and/or mosses to study (1) differences between ground cover types with respect to their effects on microenvironment and seedling emergence and (2) how these effects interact with seed size and seed sowing position. Increasing amounts of both cover types led to increasing soil humidity, whereas temperature amplitude and illumination were decreased. However, since grass litter decomposed much faster than bryophytes, light conditions for germination under grass litter improved considerably with time. Although seedling emergence varied significantly between species, ground cover types and cover amounts, seed position alone explained about 50% of the variation in the data set. Additionally, we found an important interaction between seed size, seed position and cover type: large-seeded species showed a fitness advantage when seeds were situated beneath a cover, irrespective of cover type, which disappeared when seeds were shed on top of a cover layer. We suggest that this interaction may be ecologically and evolutionarily relevant because it may lead to changes in species composition and diversity of plant communities as a consequence of changes in the amount and type of ground cover.

Biopriming of sunflower (Helianthus annuus L.) seed with Pseudomonas fluorescens for improvement of seed invigoration and seedling growth

Abstract: Biopriming treatment is potentially able to promote rapid and more uniform seed germination and plants growth associated with bacterial coatings. In this study, we report application of some effective biological agents on sunflower seed and their impact on seedling. We investigated the effects of 30 strains of Pseudomonas fluorescens on improving sunflower seed germination and promotion of seedling growth. After selection of efficient strains, efficacy of biopriming seed treatment was compared with seed inoculation and priming treatments. Two strains, including UTPf76 and UTPf86, were selected for next experiments because they enhanced seed factors such as germination index, germination percentage, germination rate and vigor index and also seedling growth indices including root length, shoot height, dry and wet weight of seedlings and numbers of lateral roots. In biopriming, the selected strains were applied to the seed during osmopriming with NaCl. Biopriming was significantly improved by the capability of these strains and the highest amount (P= 0.01) of shoot height (28.2 cm), root length (35.9 cm) and seedling weight (8.9gr) reached, in comparison with other treatments and the control. As a conclusion, biopriming with Pseudomonas fluorescens UTPf76 and UTPf86 have provided very well establishment and adherence of bacteria to the seed, before planting, and thus is suggested as a proper treatment for enhancement of seed indices and improvement of seedling growth.

Phenological Variation and its Relation with Yield in several Wheat (Triticum aestivum L.) Cultivars under Normal and Late Sowing Mediated Heat Stress Condition

Abstract: Phenological performance in relation to yield of five modern varieties of wheat ‘Sourav’, ‘Pradip’, ‘Sufi’, ‘Shatabdi’ and ‘Bijoy’ were evaluated under two growing environments; one is normal growing environment (sowing at November 30) and the other is post anthesis heat stressed environment (sowing at December 30). In case of late seeding, the varieties phased a significant level of high temperature stress that also significantly affected the required days to germination, booting, anthesis, maturity of all varieties including the yield as compared to normal sowing treatment. The temperature during the grain filling or grain maturing period was near 23°C in case of normal seeding and it was near about 28°C to 30°C and sometimes reached above this range in the later period of late seeded treatment. In the normal sowing treatment the germination period was lower than the late sowing treatment as during that time the temperature was higher as compared to late sowing condition where temperature was lower. Days to anthesis and booting decreased due to late sown heat stress condition regardless the cultivars. These phenological characteristics under heat stressed condition led the wheat cultivars to significantly lower the grain yield as compared to normal condition. Due to heat stress, the yield reduction was 69.53% in ‘Sourav’, 58.41% in ‘Pradip’, 73.01% in ‘Sufi’, 55.46% in ‘Shatabdi’ and 53.42% in ‘Bijoy’.

Doses, fontes e épocas de aplicação de nitrogênio em trigo irrigado em plantio direto

Abstract: The objective of this work was to evaluate the effects of different doses and sources of nitrogen, applied at sowing or at side-dressing, on the yied components and grain yield of irrigated wheat, under no-tillage. Nitrogen sources with or without the nitrification inhibitor (Entec) were used for applications at sowing or at side-dressing periods. Wheat was cultivated in Selviria, state of Mato Grosso do Sul, Brazil in a low-altitude Cerrado region. A randomized block design was used in the factorial arrangement 5x3x2, with four replicates. Treatments consisted of the combination of: five N doses, 0, 50, 100, 150 and 200 kg ha-1; three sources, Entec, ammonium sulfate, and urea; and two application times, at sowing, near of the lines, or at side-dressing. The different N sources had similar influence on plants height and grain yield of irrigated wheat. Nitrogen applications, totally at sowing and in the traditional way, at sowing and at side-dressing, are both equally viable. The increment of the N doses up to 121.5 kg ha-1 increases the grain yield, independently of application time and N source.

Tillage and traffic effects (planters and tractors) on soil compaction and soybean (Glycine max L.) yields in Argentinean pampas

Abstract: Direct drilling systems usually have lower traffic intensities than those using conventional tillage, but despite this, after several years of continuous direct drilling yields tend to decrease. This could be the result of increased weed control problems and root diseases as well as a gradual increase in soil compaction due to agricultural traffic. The draft required, soil cone index, root growth, soybean ( Glycine max L.) yield and traffic (planters and tractors) compaction over the subsequent three growing seasons were measured. This initially high level of soil compaction in some direct sowing systems might suggest that the impact of subsequent traffic would be minimal, but data have not been consistent. Soil compaction is caused by the high traffic intensity and weight of tractor and seeding machines and combines in harvest operations, especially when these operations are carried out on wet soil or with high ground pressure. The techniques commonly used for control and management of topsoil and subsoil compaction are: subsoiling and chiseling and axle load reduction. Outlined hypothesis was: Traffic with high axle load equipment increases soil compaction and decreases soybean yield. This article quantifies: (a) the effects of subsoiling and chisel plowing were carried out at 350 and 280 mm depth, respectively, on soil compacted under 12 years of direct drill systems and (b) traffic effect on this soil conditions of two equipment for direct sowing (planters and tractors) on soybean yields ( G. max L.) with two different loads: light equip (LE) and heavy equip (HE). The study showed that: In topsoil for three growing season, traffic with HE (185 kN) caused mean values of CI of 2178, 1506 and 1406 kPa for direct sowing, chiseled and subsoiled soil, respectively, while for the LE (127 kN) the values were of 1855, 1210 and 1206 kPa, respectively. Also in the subsoil traffic with HE caused higher CI values than the LE in all treatments. The CI mean values of the HE traffic were: 2465, 1920 and 1854 kPa for direct sowing, chiseled and subsoiled soil, respectively, while the LE traffic produced 2298, 1639 and 1637 kPa, respectively. For three growing seasons the HE traffic in soil under direct sowing reduces soybean grain yields close to 460 kg ha −1 , while for the LE was 250 kg ha −1 . When the traffic was made with LE on subsoiled soil there is an effective increase in soybean grain yields of about 330 kg ha −1 .

The Effects of Spent Engine Oil on Soil Properties and Growth of Maize (Zea mays L.)

Abstract: The effect of spent engine oil (SEO) on soil properties and growth of maize (Zea mays L.) was investigated. Five treatments (0.0, 0.2, 0.4, 0.6 and 0.8 l/kg) of the spent oil were applied to soil in perforated poly bags with maize stands at four weeks after sowing. Soil analysis showed that SEO had no effect on both the pH and texture of the soil. Organic C, N and Mg in the contaminated soils increased compared to the control. There was decrease in concentration of P due to soil contamination. Heavy metals (Fe, Cu, Zn and Pb) concentrations of soil increased with increasing concentration of oil. Plant height, root number and root length of maize plants grown in the contaminated soils were adversely affected. The grain yield of the plants in the contaminated soils was significantly reduced

Qualidade fisiológica e produtividade de sementes de soja

Abstract: There is currently intense research on obtaining information about higher soybean productivity and, in this context, using high quality seeds is extremely important to farmers. With the objective of evaluating the effects of soybean seed vigor on productivity, seed lots with high and low vigor were sown at three different densities: the certified germination %, the certified germination % plus 15% as a correction factor and, from the result of field emergence. The seedling population after emergence was not changed so that the field condition that farmers face when sowing variable quality seeds could be reproduced. During plant development, the following parameters were evaluated: initial stand, plant height at 21 and 75 days after sowing, number of pods and seeds per plant, weight of one thousand seeds, and yield/area. The results showed that: the yield/area of high vigor seed lots is on average up to 9% higher; the seedlings from high vigor seeds are taller at 21 days after sowing.

Use of a Rolled-rye Cover Crop for Weed Suppression in No-Till Soybeans

Abstract: Cover crop management with a roller/crimper might reduce the need for herbicide. Weed suppression from a rolled cereal rye cover crop was compared to no cover crop with and without postemergence herbicide application in no-till soybean. The experiment was designed as a two-way factorial with rye termination and soybean planting date as the first factor and weed control treatment as the second. Cereal rye was drill-seeded in late September and managed using glyphosate followed by a roller/crimper in the spring. Soybean was no-till seeded after rolling and glyphosate was applied postemergence about 6 wk after planting to half the plots. Rye biomass doubled when delaying rye kill by 10 to 20 d. Weed density and biomass were reduced by the rye cover crop in all site–location combinations except one, but delaying rye kill and soybean planting date only reduced both weed density and biomass at a single location. The cover crop mulch provided weed control similar to the postemergence herbicide in two of...

Influência do tamanho da semente na qualidade fisiológica e na produtividade da cultura da soja

Abstract: Seed size has received special attention by researchers, who have studied aspects related to seed performance and the resulting plant. The objectives of this study were to evaluate the effects of seed size on initial plant growth, grain yield and the physiological seed quality of soybeans by testing seeds of three cultivars (BRSMG 752S, BRSMG 790A and BRSMG 750SRR), graded into three sizes (4.0 mm, 5.0 mm and 6.0 mm). No-till planting was done on December 6 th , 2007 and the plants thinned 21 days after emergence to 13 plants per meter. Harvesting and seed threshing were done manually on April 11 th , 2008. After harvesting, seeds were manually graded into three sizes by using round perforation screens of 6.0 mm, 6.5 mm and 7.0 mm. The field trials were set up in a

Mean germination time estimates the relative emergence of seed lots of three cucurbit crops under stress conditions

Abstract: Summary A wide range of seedling emergence in commercial seed lots of watermelon (10 lots), melon (10 lots) and cucumber (9 lots), all with standard germinations above 98%, was seen in low temperature emergence (LTE), high temperature (HTE) and an 8 cm deep sowing (MSE) in the field and in salt stress conditions (SSE) in trays at 20°C. Final emergence was closely related to both the rate of emergence, measured as mean emergence time (MET; the reciprocal of the rate of emergence), and to the mean germination time (MGT; the reciprocal of the rate of germination) for physiological germination (2 mm radicle) in the laboratory at 25°C. Slower germinating and emerging lots, so-called low vigour lots, had lower levels of emergence in all sowings. Single early counts of physiological germination identified low vigour lots for all three species and are suggested as a quick routine test. The physiological age of the seed lots, determined using accelerated ageing (45°C in 100% relative humidity) and controlled deterioration (45°C and 20 or 24% moisture content), was significantly related to MGT which was higher (i.e. germination was slower) in physiologically older seed. Previous work suggests that cucurbit seeds appear to retain germination capacity over several years although ageing is reflected in a slower rate of germination (high MGT). MGT can also be described as the length of the lag period from the start of imbibition to radicle protrusion. We propose that this period is needed for the repair of the effects of ageing and is therefore longer in aged seeds.

Stalk yield and technological attributes of planted cane as related to nitrogen fertilization

Abstract: A still unclear question related to sugarcane cropping refers to the low response of the planted cane to nitrogen fertilization. Two experiments were carried out in areas under a Typic Hapludox, located in Pirassununga, Sao Paulo State, Brazil, and an Arenic Kandiudult, located in Jaboticabal, Sao Paulo State, Brazil, with the objective to evaluate planted cane response to nitrogen fertilization at planting. The experimental design was organized as random blocks and treatments consisted of three N rates (40, 80, and 120 kg ha-1 N-urea) and a control without N. Nitrogen fertilizers were applied to the bottom of the planting furrow and then incorporated into the soil. During the maximum growth stage, +1 leaf samples were collected from all experimental plots to evaluate the crop nutritional status. In the Pirassununga experiment, N fertilization at planting increased N, K, Mg, and S contents in the leaves and increased the stalk yield, without effect in the technological attributes. Conversely, no stalk yield response was observed at the Jaboticabal experiment, but N fertilization benefited the stalk technological attributes. The N rates increased the sugar yield per hectare in both experiments. The highest margin of agricultural contribution was obtained at the rate of 40 kg ha-1 N.

Effect of fertilizer levels and plant densities on yield and protein contents of autumn planted maize

Abstract: -1 and 0 kg Zn ha -1 and crop was sown at plant density of 57100 plants ha -1 . Increasing fertilizer levels and plant densities linearly increased plant height and grain yield. Application of Zinc accelerated tasseling and silking of maize crop, however the application of nitrogen had no significant effect on tasseling and silking. The fertilizer levels and plant densities also significantly affected protein contents of maize grain. Application of nitrogen at higher levels improved protein contents of grain however, opposite was true for protein contents of grains collected from the crop sown under higher plant densities. It was concluded that application of fertilizer at 250 kg N ha -1 and 15 kg Zn ha -1 and the sowing of crop at plant density of 99900 plants ha -1 showed

Growth and Yield of Aerobic Rice as Influenced by Integrated Weed Management Practices

Abstract: A field experiment was conducted during kharif 2009 at Zonal Agricultural Research Station, V. C. Farm, Mandya, Karnataka. The experiment consisted of 12 treatments laid out in randomized complete block design with three replications consisting of four pre-emergence herbicides integrated with one intercultivation at 40 days after sowing, hand weeding twice at 20 and 40 days after sowing, intercultivation thrice at 20, 40 and 60 days after sowing compared with weed free and unweeded check. The predominant weed flora observed in the experimental field were Echinochloa colonum, Digitaria marginata, Ageratum conyzoides, Spilanthus acmella, Commelina benghalensis, Celosia argentia, Cyperus iria and Cyperus rotundus. The results revealed that pre-emergence application of bensulfuron methyl+pretilachlor (6.6 GR) @ 0.06+0.60 kg/ha+one intercultivation at 40 days after sowing recorded significantly higher grain and straw yield (4425 and 5020 kg/ha, respectively), lower weed population and their dry weight (17.0 g and 2.32 g 0.25/m2, respectively). Further the net returns and B: C ratio were also high with the pre-emergence application of bensulfuron methyl + pretilachlor (6.6 GR) @ 0.06 + 0.60 kg/ha+one intercultivation at 40 days after sowing.

Growing Zostera marina (eelgrass) from Seeds in Land-Based Culture Systems for Use in Restoration Projects

Abstract: The use of aquaculture systems to grow the seagrass Zostera marina (eelgrass) from seeds for restoration projects was evaluated through laboratory and mesocosm studies. Along the mid-Atlantic coast of North America Z. marina seeds are shed from late spring through early summer, but seeds typically do not begin to germinate until the late fall. Fall is the optimal season to plant both seeds and shoots in this region. We conducted studies to determine if Z. marina seeds can be induced to germinate in the summer and seedlings grown in mesocosms to a size sufficiently large enough for out-planting in the fall. Seeds in soil-less culture germinated in the summer when held at 14°C, with percent germination increasing with lower salinities. Cold storage (4°C) of seeds prior to planting in sediments enhanced germination and seedling survival. Growth rates of seedlings were significantly higher in nutrient enriched estuarine sediments. Results from preliminary studies were used in designing a large-scale culture project in which 15,000 shoots were grown and out-planted into the Potomac River estuary in the Chesapeake Bay and compared with an equal number of transplanted shoots. These studies demonstrate that growing Z. marina from seeds is an alternative approach to harvesting plants from donor beds when vegetative shoots are required for restoration projects.

Differential effects of several “litter” types on the germination of dry grassland species

Abstract: Question: Accumulation of litter can have serious implications on the recruitment of plant species, by modifying the physical, biological and chemical features of the microenvironment or acting as a mechanical barrier for seeds and seedlings. Isolating these different effects has rarely been achieved experimentally. Location: Transylvanian Lowland, Romania. Methods: We tested the effects of different ‘‘litter’’ types on the germination of dry grassland species using a controlled pot experiment with three natural litter types, differing in decay state and composition (Stipa pulcherrima fresh leaves, partly decomposed leaves and mixed and partly decomposed plant material) and an artificial plastic litter, with two levels of water addition. As a complementary field study, seed sowing was conducted in grassland plots with litter removal and plastic litter application. Results: Litter effects were mainly positive (intermittent watering) or neutral (frequent watering) under controlled experimental conditions, and mostly negative in the field. Seed size and environmental conditions were the major determinants of litter effects on germination. Significant differences were found in the effect of litter type on germination, much of which could be explained by chemical factors determined by the decay state, as we confirmed a higher concentration of allelopathic compounds in fresh S. pulcherrima litter than in the senescing leaf litter. Conclusions: The effects of litter on seed germination are strongly context dependent, and it is hard to define common rules that apply consistently under various environmental conditions. ‘‘Litter’’ identity and quality matter, i.e. the litter composition and decay state, and influence seed germination.