Showing papers on "Sowing published in 2004"

Changes in endogenous abscisic acid levels during dormancy release and maintenance of mature seeds: studies with the Cape Verde Islands ecotype, the dormant model of Arabidopsis thaliana

Abstract: Mature seeds of the Cape Verde Islands (Cvi) ecotype of Arabidopsis thaliana (L.) Heynh. show a very marked dormancy. Dormant (D) seeds completely fail to germinate in conditions that are favourable for germination whereas non-dormant (ND) seeds germinate easily. Cvi seed dormancy is alleviated by after-ripening, stratification, and also by nitrate or fluridone treatment. Addition of gibberellins to D seeds does not suppress dormancy efficiently, suggesting that gibberellins are not directly involved in the breaking of dormancy. Dormancy expression of Cvi seeds is strongly dependent on temperature: D seeds do not germinate at warm temperatures (20–27°C) but do so easily at a low temperature (13°C) or when a fluridone treatment is given to D seeds sown at high temperature. To investigate the role of abscisic acid (ABA) in dormancy release and maintenance, we measured the ABA content in both ND and D seeds imbibed using various dormancy-breaking conditions. It was found that dry D seeds contained higher amounts of ABA than dry ND after-ripened seeds. During early imbibition in standard conditions, there was a decrease in ABA content in both seeds, the rate of which was slower in D seeds. Three days after sowing, the ABA content in D seeds increased specifically and then remained at a high level. When imbibed with fluridone, nitrate or stratified, the ABA content of D seeds decreased and reached a level very near to that of ND seeds. In contrast, gibberellic acid (GA3) treatment caused a transient increase in ABA content. When D seeds were sown at low optimal temperature their ABA content also decreased to the level observed in ND seeds. The present study indicates that Cvi D and ND seeds can be easily distinguished by their ability to synthesize ABA following imbibition. Treatments used here to break dormancy reduced the ABA level in imbibed D seeds to the level observed in ND seeds, with the exception of GA3 treatment, which was active in promoting germination only when ABA synthesis was inhibited.

Legume seed inoculation technology—a review

Abstract: Inoculation of legume seed is an efficient and convenient way of introducing effective rhizobia to soil and subsequently the rhizosphere of legumes. However, its full potential is yet to be realised. Following widespread crop failures, the manufacture of high quality inoculants revolutionised legume technology in Australia in the 1960s. Many improvements to inoculants and the advent of an inoculant control service ensured that quality was optimised and maintained. Minimum standards for the number of rhizobia per seed were set after consideration of several factors including seed size and loss of viability during inoculation. Despite manufacturers' recommendations for storage and application of inoculants, there is a distinct lack of control over the inoculation process; hence the full potential of high quality products may not always be achieved. The efficacy of inoculation varies depending on several factors, all of which affect the number of viable rhizobia available for infection of legume roots. Increased numbers of viable rhizobia per seed by application of inoculant above the commercially recommended rate, results in a continued linear increase in nodulation and yield. Several studies have reported yield increases of up to 25%. However, applying higher quantities of inoculant is uneconomical and technically difficult. Alternatively, higher numbers of viable rhizobia per seed may be achieved by improving survival during seed inoculation. Despite recognition of the factors affecting survival of rhizobia on seed and a substantial demand for commercially pre-inoculated legume seed, poor survival is still a major concern. Desiccation, temperature and seed coat toxicity all influence survival of rhizobia on seed. Their adverse effects may be ameliorated by selecting tolerant rhizobial strains and legume seed cultivars with low toxicity or artificially, by the use of additives in the seed coating. The accumulation of the desiccant protectant trehalose in strains of rhizobia, may result in better survival under desiccation stress. Similarly, the accumulation of exopolysaccharide (EPS) may act as a barrier reducing excessive water loss. Polymeric adhesives such as gum arabic, methyl cellulose and polyvinyl pyrollidone (PVP) have improved survival. However, studies of additives used in inoculation have been ad hoc and little of their mode of action is understood. A better understanding of the mechanisms involved in the protection of rhizobia from adverse conditions will assist in defining the optimum conditions for seed inoculation and storage to ensure a higher quality product for farmers at the time of sowing.

Effects of Residue Decomposition on Productivity and Soil Fertility in Rice–Wheat Rotation

Abstract: Rice (Oryza saliva L.)-wheat (Triticum aestivum L.) farmers in India burn or remove residues to facilitate seedbed preparation. Incorporation of residues before planting of the next crop generally decreases yields due to N immobilization. Since a window of about 40 d is available between rice harvest and wheat planting, the effect of time of incorporation on rice residue decomposition and N mineralization-immobilization was studied in 1992-1993. The mass loss of residue was 25% for a 10-d, 35% for a 20-d, and 51% for a 40-d decomposition period before wheat planting. Nitrogen release from residue ranged from 6 to 9 kg ha -1 during the wheat season. The immobilization of urea N decreased when residue was allowed to decompose for 10-d or longer. Based on these studies, a long-term (1993-2000) experiment was conducted on a sandy loam soil to examine the effect of time of residue incorporation before sowing wheat when compared with burning or removal of residue on yields, N-use efficiency, and soil fertility. The effect of wheat residue incorporation with green manure (GM, Sesbania cannabina L.) on subsequent rice yields was also determined. Residue incorporation for 10 to 40 d had no effect on wheat yields. Rice yields increased (0.18-0.39 Mg ha -1 ) when wheat residue was incorporated with GM. Starter N applied at residue incorporatidn did not influence wheat yields but decreased N recovery efficiency. Physiological efficiency was higher when rice straw was incorporated in wheat and when wheat straw plus GM were incorporated in rice than when rice straw was incorporated for 10 d or when the straw was burned. The long-term application of rice residue increased C accumulation in soil.

Nitrogen fertilizer timing and application method affect weed growth and competition with spring wheat

Abstract: Managing crop fertilization may be an important component of integrated weed management systems that protect crop yield and reduce weed populations over time. A field study was conducted to determine the effects of various timings and application methods of nitrogen (N) fertilizer on weed growth and spring wheat yield. Nitrogen fertilizer was applied the previous fall (October) or at planting (May) at a dose of 50 kg ha−1. Nitrogen application treatments consisted of granular ammonium nitrate applied broadcast on the soil surface, banded 10 cm deep between every crop row, banded 10 cm deep between every second crop row, or point-injected liquid ammonium nitrate placed between every second crop row at 20-cm intervals and 10 cm deep. Treatments were applied in 4 consecutive yr to determine annual and cumulative effects over years. Density and biomass of wild oat, green foxtail, wild mustard, and common lambsquarters were sometimes lower with spring- than with fall-applied N. Spring wheat yield was ...

The effect of sowing date, stale seedbed, row width and mechanical weed control on weeds and yields of organic winter wheat

Abstract: Three field experiments were carried out in organically grown winter wheat in Denmark. The treatments were sowing time (normal or late sowing) and false seedbed, row width (12 cm and 24 cm) and weed control method (untreated, mechanical weed control (weed harrowing at 12 cm supplemented with inter-row hoeing at 24 cm), and herbicide weed control). Weed biomass in mid-summer was greatest on plots sown at the normal sowing time (compared to delayed sowing) and was reduced by mechanical or chemical weed control (compared with untreated plots). Row width alone had no influence on weed biomass, but in the experiment with high weed pressure, the more intensive mechanical weed control used at a row width of 24 cm reduced weed biomass. Normal sowing time tended to give higher yields, but this was only statistically significant in one of the three experiments. Wide rows gave a yield decrease in the experiment with low weed pressure. The effect of weed control on yield was dependent on the weed pressure. At low weed pressure, mechanical weed control caused a yield decrease compared to untreated or herbicide treated. At intermediate weed levels there were no differences, whereas at high weed pressure, mechanical weed control and herbicide treatment caused a yield increase compared to untreated. False seedbeds were shown to contribute to a decrease in the soil seed reserve.

Response of Soybean Yield Components to Management System and Planting Date

Abstract: Soybean [Glycine max (L.) Merr.] area has increased tremendously in the upper Midwest over the last decade, but little information exists regarding the impact of management systems on soybean yield components. Our objective was to assess the effect of management system and planting date on soybean seed yield components and their development for environments typical of the upper Midwest. A field study was conducted from 1997 to 2000 using five management systems. Two newer released cultivars (CX232 and Spansoy 250) and one older cultivar (Hardin) were planted at two planting dates. Few interactions were observed in this study. Management system influenced development of the different yield components and produced seed mass ranging from 10.5 to 16.5 g 100 seed -1 , seed number from 2878 to 3824 seeds m -2 , pod number from 1182 to 1571 pods m -2 , and seeds per pod from 2.36 to 2.49 seeds pod -1 . Harvest index ranged from 56.2 to 58.0% across management systems. Hardin produced the highest harvest index (60.1%) and Spansoy 250 the lowest harvest index (54.5%). Tillage system affected yield components, with no-tillage systems having 15, 9, and 9% greater seed mass, seed number per square meter, and pod number per square meter than the conventional tillage system, respectively. Early planting date produced higher seed number, pod number, and harvest index but lower seed number per pod than the late planting date. In conclusion, differences in yield components and their development emphasize the complexity of plant compensation in response to management system and tillage system.

Calcium and humic acid affect seed germination, growth, and nutrient content of tomato (Lycopersicon esculentum L.) seedlings under saline soil conditions

Abstract: The effects of calcium and humic acid on seed germination, growth and macro- and micro-nutrient contents of tomato (Lycopersicon esculentum L.) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 2000 mg kg−1) and calcium (0, 100, 200 and 400 mg kg−1) were applied to growth media treated with 50 mg NaCl kg−1 before sowing seeds. Seed germination, hypocotyl length, cotyledon width and length, root size, shoot length, leaf number, shoot and root fresh weights, and shoot and root dry weights of the plant seedlings were determined. Macro- and micro-nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of shoot and root of seedlings were also measured. Humic acid applied to the plant growth medium at 1000 mg kg−1 concentration increased seedling growth and nutrient contents of plants. Humic acid not only increased macro-nutrient contents, but also enhanced micro-nutrient contents of plant organs. However, high levels of humic acid arrested plant growth or de...

Handbook of Seed Physiology : Applications to Agriculture

Abstract: * About the Editor * Contributors * Preface * SECTION I: GERMINATION IN THE SOIL AND STAND ESTABLISHMENT * Chapter 1. Seedbed Preparation--The Soil Physical Environment of Germinating Seeds (Amos Hadas) * Introduction * Environmental Requirements of Germinating Seed * Soil Environment--Physical Aspects * Seedbed Preparation, Characterization of Seedbed Attributes, and Seedbed Environment Conditions and Seed Germination * Water Uptake by Seeds and Seedlings * Seed-Soil Water Relationships * Modeling Seed Germination and Seedbed Physical Attributes * Concluding Remarks * Chapter 2. The Use of Population-Based Threshold Models to Describe and Predict the Effects of Seedbed Environment on Germination and Seedling Emergence of Crops (William E. Finch-Savage) * Introduction * Imbibition * Germination * Other Germination Models * Postgermination Seedling Growth * Threshold Models: Prediction of Germination and Emergence Patterns in the Field * Summary and Conclusions * Appendix * Chapter 3. Seed and Agronomic Factors Associated with Germination Under Temperature and Water Stress (Mark A. Bennett) * Introduction * Seed Coats * Seed Size * Seed Water Uptake * Radicle Emergence and Root System Development * Genetic Links to Germination Temperature Limits * Seed Production and Seed Vigor * Sowing Depths and Planter Technology * Tillage Systems and Soil Structure Effects * Interactions with Seed Treatments and Other Crop Protection Chemicals * Screening Protocols for Germination Tolerance to Low Temperature and Water Stress * Concluding Remarks * Chapter 4. Methods to Improve Seed Performance in the Field (Peter Halmer) * Introduction * Changing Seed Form and Lot Composition * Physiological Enhancement * Physiological Responses to Enhancement * Ecological Aspects of Seed Hydration * Conclusions and Future Directions * SECTION II: DORMANCY AND THE BEHAVIOR OF CROP AND WEED SEEDS * Chapter 5. Inception, Maintenance, and Termination of Dormancy in Grain Crops: Physiology, Genetics, and Environmental Control (Roberto L. Benech-Arnold) * Introduction * Physiology of Dormancy in the Cereal Grain * Physiology of Dormancy in the Sunflower Seed * The Expression of Dormancy in Grain Crops * Removing Dormancy at an Industrial Scale * Genetics and Molecular Biology of Dormancy in Grain Crops * Environmental Control of Dormancy in Grain Crops * Concluding Remarks * Chapter 6. Preharvest Sprouting of Cereals (Gary M. Paulsen and Andrew S. Auld) * Introduction * The Preharvest Sprouting Process * Physiological Control of Preharvest Sprouting * Quality of Products from Sprouted Cereals * Measurement of Preharvest Sprouting * Controlling Sprouting by Breeding * Controlling Sprouting in the Field * Chapter 7. The Exit from Dormancy and the Induction of Germination: Physiological and Molecular Aspects (Rodolfo A. Sanchez and R. Alejandra Mella) * Introduction * The Effects of Light Photoreceptors * Embryo Growth Potential * Endosperm Weakening * Termination of Dormancy: Its Relationship with the Synthesis and Signaling of Gibberellins and ABA * Concluding Remarks * Chapter 8. Modeling Changes in Dormancy in Weed Soil Seed Banks: Implications for the Prediction of Weed Emergence (Diego Batlla, Betina Claudia Kruk, and Roberto L. Benech-Arnold) * Introduction * Dormancy: Definitions and Classification * How Is Dormancy Level Expressed? * Environmental Factors Affecting Dormancy Level of Seed Populations * Factors That Terminate Dormancy * Conceptualizing the System with Modeling Purposes * Modeling Dormancy Changes in Weed Seed Banks As Affected by the Environment * Concluding Remarks * SECTION III: SEED LONGEVITY AND STORAGE * Chapter 9. Orthodox Seed Deterioration and Its Repair (Miller B. McDonald) * Introduction * The First Seed * Seed Deterioration * Mechanisms of Orthodox Seed Deterioration * Free Radical Production * Free Radicals and Their Effects on Lipids * How Do Free Radicals Cause Lipid Peroxidation? * What Is the Influence of Seed Moisture Content on Free Radical Assault? * Do Free Radicals Attack Only Lipids? * Why Suspect Free Radical Attack on Mitochondria? * How Are Seeds Protected Against Free Radical Attack? * Raffinose Oligosaccharides and Their Protective Role * Repair of Seed Damage * Model of Seed Deterioration and Repair During Priming/Hydration * Conclusions * Chapter 10. Recalcitrant Seeds (Patricia Berjak and Norman W. Pammenter) * Seed Characteristics--The Broad Picture * Seed Behavior * The Suite of Interacting Processes and Mechanisms Involved in Desiccation Tolerance * Drying Rate and Causes of Damage in Recalcitrant Seeds * SECTION IV: INDUSTRIAL QUALITY OF SEEDS * Chapter 11. Processing Quality Requirements for Wheat and Other Cereal Grains (Colin W. Wrigley and Ferenc Bekes) * Introduction * The Range of Grain Species Used Industrially * Cereal Grains and Our Diet * Uses of Cereal Grains * Wheat-Grain Quality Traits: A Molecular Basis * Grain Hardness * Starch Properties * Conclusion * Chapter 12. Grain Quality in Oil Crops (Leonardo Velasco, Begona Perez-Vich, and Jose M. Fernandez-Martinez) * Introduction * Components of Grain Quality in Oil Crops and Factors Influencing Them * Oil Quality * Meal Quality * Breeding and Production Strategies * Chapter 13. The Malting Quality of Barley (Roxana Savin, Valeria S. Passarella, and Jose Luis Molino-Cano) * Introduction * Grain Structural Components That Affect Malting Quality * Genotypic and Environmental Factors Affecting Malting Quality * Achieving Barley-Grain Quality Targets * Conclusions * Index * Reference Notes Included

Efficiency of the magnetic treatment of broad bean seeds cultivated under experimental plot conditions

Abstract: A b s t r a c t. The tests were carried out in the Institute of Soil Science and Plant Cultivation in Pu³awy under experimental plot conditions in the years 2000-2001. The factor of the first order were two varieties of broad bean: Nadwiœlanski – a traditional form and Tim – a self-determining form, while the second factor wa s–3e xposure doses of magnetic induction intensity: The magnetic treatment of the seed was done in the Department of Physics at the University of Agriculture in Lublin using a specially constructed device for the magnetic treatment of seeds prior to sowing equipped with an electromagnet with fluent regulation of magnetic induction. The research confirmed the positive effect of the magnetic treatment on the germination and emergence of both broad bean cultivars. Plant emergence was more regular after the use of the aforementioned treatment and occured 2-3 days earlier in comparison to the control plants. The magnetic treatment of broad bean seeds prior to sowing exerted a significant influence on the increase of seed yield. However, the efficiency of this treatment was dependent on the weather. The gain in seed yield resulting from the pre-sowing treatment of seeds with a magnetic field for both forms of broad bean was due to the higher number of pods per plant and the fewer plant losses in the unit area in the growing season.

Integrated management of fusarium wilt of chickpea with sowing date, host resistance, and biological control.

Abstract: Landa, B B, Navas-Cortes, J A, and Jimenez-Diaz, R M 2004 Integrated management of Fusarium wilt of chickpea with sowing date, host resistance, and biological control Phytopathology 94:946-960 A 3-year experiment was conducted in field microplots infested with Fusarium oxysporum f sp ciceris race 5 at Cordoba, Spain, in order to assess efficacy of an integrated management strategy for Fusarium wilt of chickpea that combined the choice of sowing date, use of partially resistant chickpea genotypes, and seed and soil treatments with biocontrol agents Bacillus megaterium RGAF 51, B subtilis GB03, nonpathogenic F oxysporum Fo 90105, and Pseudomonas fluorescens RG 26 Advancing the sowing date from early spring to winter significantly delayed disease onset, reduced the final disease intensity (amount of disease in a microplot that combines disease incidence and severity, expressed as a percentage of the maximum possible amount of disease in that microplot), and increased chickpea seed yield A significant linear relationship was found between disease development over time and weather variables at the experimental site, with epidemics developing earlier and faster as mean temperature increased and accumulated rainfall decreased Under conditions highly conducive for Fusarium wilt development, the degree of disease control depended primarily on choice of sowing date, and to a lesser extent on level of resistance of chickpea genotypes to F oxysporum f sp ciceris race 5, and the biocontrol treatments The main effects of sowing date, partially resistant genotypes, and biocontrol agents were a reduction in the rate of epidemic development over time, a reduction of disease intensity, and an increase in chickpea seedling emergence, respectively Chickpea seed yield was influenced by all three factors in the study The increase in chickpea seed yield was the most consistent effect of the biocontrol agents However, that effect was primarily influenced by sowing date, which also determined disease development Effectiveness of biocontrol treatments in disease management was lowest in January sowings, which were least favorable for Fusarium wilt Sowing in February, which was moderately favorable for wilt development, resulted in the greatest increase in seed yield by the biocontrol agents In March sowings, which were most conducive for the disease, the biocontrol agents delayed disease onset and increased seedling emergence B subtilis GB03 and P fluorescens RG 26, applied either alone or each in combination with nonpathogenic F oxysporum Fo 90105, were the most effective treatments at suppressing Fusarium wilt, or delaying disease onset and increasing seed yield, respectively The importance of integrating existing control practices, partially effective by themselves, with other control measures to achieve appropriate management of Fusarium wilt and increase of seed yield in chickpea in Mediterranean-type environments is demonstrated by the results of this study

Nitrogen Balance as Affected by Application Time and Nitrogen Fertilizer Rate in Irrigated No-Tillage Maize

Abstract: High N requirements of no-tillage maize (Zea mays L.) make it imperative to develop management strategies that optimize crop production and N use efficiency (NUE). A 4-yr field experiment was conducted at Balcarce (37°45'S, 58°18'W), Argentina, on a Typic Argiudoll and a Petrocalcic Paleudoll. The objective was to evaluate the effect of urea rate (0, 70, 140, and 210 kg N ha -1 ) at planting (FPL) or six-leaf stage (FV6) on NH3 volatilization, denitrification, soil residual nitrate, soil microbial biomass N (MBN), N uptake, grain yield, and unaccounted N (UN). Grain yield was 10.5 and 11.2 Mg ha -1 , and N uptake at physiological maturity was 168 and 192 kg N ha -1 (average of N rates) for FPL and FV6, respectively. Gaseous N losses ranged from 7.6 to 13.8% of applied N and were not affected by the fertilizer time. Relative to unfertilized control, fertilized treatments increased MBN (13.4 kg N ha -1 ') similarly for both fertilization times. For FPL, UN was 55, 69, 86, and 103 kg N ha -1 for 0, 70, 140, and 210 kg N ha -1 , respectively. For FV6, UN was 55, 46, 49, and 34 kg N ha -1 for 0, 70, 140, and 210 kg N ha -1 , respectively. The losses were attributed to nitrate (NO,) leaching. Results of this experiment show that high fertilizer NUE in combination with economically competitive grain yields can be obtained when N is applied at V6 because gaseous N losses are low (less than 13.8%) and NO 3 leaching would be reduced.

Soybean Growth and Development in Various Management Systems and Planting Dates

Abstract: Soybean [Glycine max (L.) Merr.] has the ability to produce similar yields across a broad range of management systems and planting dates. Our objective was to better understand growth factors affecting yield component compensation in the upper Midwest under different management systems. An older cultivar, Hardin, and two newer cultivars, DeKalb CX232 and Spansoy 250, were grown in five management systems during four growing seasons from 1997 to 2000. Four of the five management systems were located near Arlington, WI, on a silt loam soil consisting of conventional and no-tillage systems with and without irrigation. The fifth management system was located near Hancock, WI, on a conventionally tilled, irrigated sandy loam soil. Yield component compensations gave similar grain yield among cultivars, planting dates, and management systems. At R6, CX232 and Spansoy 250 averaged greater dry matter (DM) accumulation, leaf area index (LAI), and crop growth rate (CGR) than Hardin. Early planted soybean had more total DM than the late-planted soybean. No-tillage systems produced more total DM, LAI, and CGR after R3 than the two conventional tillage systems at Arlington. Irrigated systems had higher LAI than the nonirrigated systems. These results indicate that the compensatory growth and alterations in plant development among cultivars, management systems, and planting dates had no impact on soybean yield.

Escherichia coli Contamination of Vegetables Grown in Soils Fertilized with Noncomposted Bovine Manure: Garden-Scale Studies

Abstract: In this study we tested the validity of the National Organic Program (NOP) requirement for a ≥120-day interval between application of noncomposted manure and harvesting of vegetables grown in manure-fertilized soil. Noncomposted bovine manure was applied to 9.3-m2 plots at three Wisconsin sites (loamy sand, silt loam, and silty clay loam) prior to spring and summer planting of carrots, radishes, and lettuce. Soil and washed (30 s under running tap water) vegetables were analyzed for indigenous Escherichia coli. Within 90 days, the level of E. coli in manure-fertilized soil generally decreased by about 3 log CFU/g from initial levels of 4.2 to 4.4 log CFU/g. Low levels of E. coli generally persisted in manure-fertilized soil for more than 100 days and were detected in enriched soil from all three sites 132 to 168 days after manure application. For carrots and lettuce, at least one enrichment-negative sample was obtained ≤100 days after manure application for 63 and 88% of the treatments, respectively. The current ≥120-day limit provided an even greater likelihood of not detecting E. coli on carrots (≥1 enrichment-negative result for 100% of the treatments). The rapid maturation of radishes prevented conclusive evaluation of a 100- or 120-day application-to-harvest interval. The absolute absence of E. coli from vegetables harvested from manure-fertilized Wisconsin soils may not be ensured solely by adherence to the NOP ≥120-day limit. Unless pathogens are far better at colonizing vegetables than indigenous E. coli strains are, it appears that the risk of contamination for vegetables grown in Wisconsin soils would be elevated only slightly by reducing the NOP requirement to ≥100 days.

Yield Loss Caused by Meloidogyne graminicola on Lowland Rainfed Rice in Bangladesh

Abstract: The impact of Meloidogyne graminicola on growth and yield of lowland rainfed rice was assessed with and without carbofuran in a rice-wheat rotation area of northwestern Bangladesh. The experiment was conducted on farmer fields and at a research station, with experimental plots arranged in a randomized complete block design. Prior to transplanting, rice seedling height and dry weight were greater (P

Accumulation of Genistein and Daidzein, Soybean Isoflavones Implicated in Promoting Human Health, Is Significantly Elevated by Irrigation

Abstract: To circumvent drought conditions persisting during seed fill in the mid-south U.S. soybean production region, researchers have developed the early soybean (Glycine max [L.] Merr.) production system (ESPS), which entails early planting of short-season varieties. Because soybean supplies a preponderance of the world's protein and oil and consumption of soy-based foods has been associated with multiple health benefits, the effects of this agronomic practice on seed quality traits such as protein, oil, and isoflavones should be investigated. Four cultivars of soybean, two from maturity group IV and two from maturity group V, were planted in April (ESPS) and May (traditional) in a two-year study at Stoneville, MS. Near-infrared analysis of soybean seed was utilized to determine the percentages of protein and oil. Dependent upon variety, the oil content of the early-planted crop was increased by 3-8%, whereas protein was not significantly changed. Visualization of protein extracts fractionated by sodium dodecyl sulfate-polyacrylamide electrophoresis and fluorescence two-dimensional difference gel electrophoresis revealed that early planting did not affect the relative accumulation of the major seed-storage proteins; thus, protein composition was equal to that of traditionally cultivated soybeans. Maturity group IV cultivars contained a higher percentage of oil and a lower percentage of protein than did the maturity group V cultivars, regardless of planting date. Gas chromatographic separation of fatty acids revealed that the percentages of saturated and unsaturated fatty acids were not significantly altered by planting date. Methanol extracts of seed harvested from different planting dates when analyzed by high-performance liquid chromatography showed striking differences in isoflavone content. Dependent upon the variety, total isoflavone content was increased as much as 1.3-fold in early-planted soybeans. Irrigation enhanced the isoflavone content of both early- and late-planted soybeans as much as 2.5-fold. Accumulation of individual isoflavones, daidzein and genistein, was also elevated by irrigation. Because this cultural practice improves the quality traits of seeds, ESPS provides an opportunity for enhancing the quality of soybean.

Weed Control in Maize (Zea mays L.) Through Sorghum Allelopathy

Abstract: Sorghum allelopathy has been utilized as an economical and natural technique for controlling weeds in some field crops like wheat (Triticum aestivum L.), maize (Zea mays L.), rice (Oryza sativa L.), mungbean (Vigna radiata L.) and Brassica (Brassica juncea L.). It can be used as sorgaab (water extract of mature sorghum plants), sorghum mulch, sorghum soil incorporation or included in crop rotation. Two field experiments were conducted for two years in the summer of 1997 and 1998. In Experiment 1, the response of maize (Zea mays L.) and summer weeds to foliar applications of sorgaab, hand weeding and herbicide spray was studied. In Experiment 2, the comparative efficacy of sorgaab at 15, 30 and 45 days after sowing (DAS) and sorghum mulch for controlling weeds were studied. Sorgaab foliar spraying controlled from 18–50% weeds and increased maize grain yield by 11–44%. Mature and chaffed sorghum herbage (10–15 Mg ha−1) surface applied at sowing controlled up to 26–37% weeds and increased maize yiel...

Effects of Straw Mulch on Pest Insects, Predators, and Weeds in Watermelons and Potatoes

Abstract: Physical and biotic effects of straw mulch applied at two different times to potatoes and watermelons were assessed in field trials over 2 yr. Plots with straw mulch generally had lower soil temperatures and higher soil moisture than control (weedy, no straw) plots. When straw was applied at planting weeds were suppressed, whereas straw applied after cultivation 4 wk after planting had less effect on weeds. In 2000, potatoes with straw at planting had fewer potato leafhoppers, Empoasca fabae (Harris) (and less associated plant damage) and more colonizing Colorado potato beetle, Leptinotarsa decemlineata (Say), adults than the other treatments. Subsequent Colorado potato beetle egg mass and larval numbers, however, were not higher in this treatment, possibly because of the higher numbers of predators in these plots as assessed by pitfall trapping. In 2001, there were no differences in numbers of colonizing potato leafhopper or Colorado potato beetle adults, but by midsummer there were more Colorado potato beetle larvae in the control plots than in the straw plots, again possibly due to differential predation. The few pests observed in the watermelon plots were not affected by the straw treatments. Potato yields were similar in all treatments, but melon yields were higher in plots with straw at planting (in which weeds were suppressed) in 2000. In 2001, when melons were planted earlier in the spring, melon plant biomass at 4 wk was lower in plots with straw at planting than in the other treatments, probably due to reduced soil temperatures. Thus, for potatoes, straw may be useful to control weeds and enhance predator numbers, but insect pests may still require control. In melons, straw should be used only if the crop is planted after the soil is sufficiently warm.

Cultivation of Sweet Sorghum (Sorghum bicolor (L.) Moench) and Determination of its Harvest Time to Make Use as the Raw Material for Fermentation, Practiced during Rainy Season in Dry Land of Indonesia

Abstract: We cultivated sweet sorghum cultivars – Wray, Keller and Rio – to confirm the feasibility of cultivation in dry land of Indonesia for monosodium glutamate (MSG) production. Stem yield of Wray was 4,790 ~ 6,593 g m−2. Sweet sorghum reached anthesis at 73 days after sowing (DAS) and was harvested 3.5 months after sowing. Stem length increased to 36 DAS, then rapidly to 320 cm by 80 DAS. Stem diameter reached 18 mm by 36 DAS. Stems enlarged for 1 month, then elongated. Thinning and weeding for 1 month after sowing produced heavy-stem plants with high yield because stem length and diameter determine stem volume and yield. Stem sugar weight increased after anthesis and reached a peak at 26–33 days after anthesis (DAA). Grain grew until 26 DAA and dried. It was harvestable after 30 DAA. Stem sugar content closely correlated with Brix indicating its value as an index of sugar in stem juice. Consequently, the optimum harvest time is determined by measuring Brix after 30 DAA (103 DAS). Yields were highest ...

Improving weed management and crop productivity in maize systems in Zimbabwe

Abstract: Keywords: Intercropping, narrow planting, precise fertilizer placement, radiation interception, leaf stripping, detasselling, Land Equivalent Ratio, maize, pumpkin, dry beans, reduced herbicide dosages In the tropics, weeds cause more crop losses and farmers spend more of their time weeding crops than in any other part of the world. Weeds form a major factor which contributes to the miserable quality of life of smallholder farmers, especially of women and children, in rural areas of sub-Saharan Africa . The effects of maize-pumpkin and maize-bean intercropping and, narrow row planting and precise basal fertilizer placement in monocrop maize, on crop and weed radiation interception (RI), crop yields, weed emergence, growth and fecundity were investigated in this study. The effects of leaf stripping (removal of the lowest 2-6 leaves) and detasselling maize at anthesis on the radiant environment and crop yields in a maize monocrop and maize-pumpkin and maize-bean intercrops were also studied to determine the impact of these interventions on yield of component crops. The aim of the studies was to generate technologies that could be integrated into the production practices of smallholder farmers to suppress weeds and alleviate the severe weeding burden faced by these farmers while ensuring high crop productivity. Maize-pumpkin and maize-bean intercropping reduced weed biomass by 50-66% when established at a density of 12,300 plants ha - 1 for pumpkins equivalent to 33% of the maize density (37,000 plants ha - 1 ), and 222,000 plants ha - 1 for beans. Lower densities of pumpkins than 33% of the maize density failed to reduce weed biomass more than that achieved by sole maize. Sole maize crops were weeded twice or thrice to achieve the same weed biomass as intercrops weeded once showed that intercropping could reduce the weeding requirements of maize by 33 to 67%. Maize grain yield was reduced by 20% in one out of four seasons in the first study on maize-pumpkin intercropping. Maize grain yield was not reduced in three seasons when the maize-pumpkin intercropping treatments were leaf stripped and/or detasselled and the trend of leaf stripping and detasselling alleviating the effects of companion crop competition on maize grain was shown in the maize-bean intercrop experiments as well. Intercrop productivity increased with leaf stripping and detasselling as a result of greater penetration of radiation to the companion crop and their effects of increasing dry matter distributed to the maize cob (indicated by 1000-grain weight, cob weight, and kernel weight cob - 1 ). Leaf stripping maize at anthesis focused on the removal of leaves that were beginning to senesce. If they would remain on the plant they would compete with the cob for assimilates as they senesce further, until necrosis. Detasselling is known to remove apical dominance and to increase radiation penetration to the middle leaves on the maize plant that produce most assimilates destined for the cob. Leaf stripping did not affect the ability of the intercrop to suppress weed growth and seed production. In maize monocrops more weed biomass and weed seeds were produced with leaf stripping and detasselling. Maize grain yield decreased with an increase in maize density from 30,000 plants ha - 1 to 36,000 and 42,000 plants ha - 1 and weed growth suppression increased with an increase in maize density in a semi arid location in Zimbabwe. Planting maize using narrow row (60 cm × 45 cm) and (75 cm × 36 cm) spatial arrangements increased radiation interception by maize plants by 16 to 24% and maize grain yields by 15 to 26% compared to wide row (90 cm × 30 cm) spatial arrangement commonly used by smallholder farmers. Weed biomass was reduced by 20 to 80%, dependent on weed species, in narrow row spatial arrangements compared to normal farmer planting patterns. The duration of the weed free period required to attain maximum yield increased from 6 weeks after emergence (WAE) in the 60 cm × 45 cm spatial arrangement to 9 WAE in the wider row spatial arrangements. It is, therefore, risky for smallholder farmers to increase maize density to suppress weeds as this will lead to maize grain yield reductions. The use of narrow rows proved to be a better option. Precise fertilizer placement (banding and spot placement) resulted in higher rates of early growth and by 4 WAE these treatments intercepted 20% more of the incoming radiation than a broadcast placement method. Weed emergence, growth and seed production was higher in the broadcast placement treatment as a result of weeds intercepting more incoming radiation and greater access to applied fertilizer nutrients. High fertilizer rates of 225 kg ha - 1 of a compound fertilizer (8% N, 14% K 2 O, 7 % P 2 O 5 ), reduced maize grain yield by 15% compared to 150 kg ha - 1 in a season characterized by drought. It was hypothesized that high concentrations of fertilizer around the root zone predisposed the maize plants to more severe effects of drought than lower fertilizer application rates. Reduced dosages of atrazine and nicosulfuron (25% of the Label Recommended Dosages, LRDs) protected maize from weeds as well as the full LRDs of each herbicide. The reduced dosages suppressed weed competition during the critical period for weed control in maize. However, the tolerant weed species Eleusine indica (L.) Gaertn., Setaria verticillata (L.) Beauv., Setaria homonyma (Stead.) Chiov. for atrazine and E. indica , Galinsoga parviflora Cav. and Portulaca oleracea L. for nicosulfuron, tended to escape the herbicide effects and survive as dosages were reduced. Reduced dosages of these herbicides have to be combined with hoe weeding or ox-cultivation to prevent the inadvertent selection of these species by the reduced dose strategy. Recalcitrant species recovering from tillage were shown to be more vulnerable to reduced herbicide toxicity in a greenhouse experiment. It was concluded that cultural weed management techniques that enhance radiation capture by the crop were effective in suppressing weed growth and seed production and increasing crop yields and should be incorporated into smallholder farmer's production practices in a systematic manner as part of Integrated Weed Management and cropping system design.

Fitomassa e cobertura do solo de culturas de sucessão ao milho na Região do Cerrado

Abstract: The objective of this study was to evaluate the biomass production and soil cover by different crops after maize cultivated in conventional tillage and no-tillage, in Cerrado conditions. The biomass of black oat, sunnhep, canavalia, pigeonpea, mucuna, sunflower and millet was obtained when they showed 50% of flowering. Soil coverage was evalluated at 30 and 60 days after sequential crops sowing, in August (during dry season), in October (at the beginning of the rainy season) and after 15 and 45 days of maize crop sowing. Mucuna showed the highest soil coverage rate during its growing. The biomass produced by sunflower had no efficiency for soil coverage. No-tillage showed the highest productions of biomass by sequential crops, compared to the conventional tillage system.