Glyphosate management strategies,weed diversity and soybean yield in Argentina

From their introduction in 1996, glyphosate resistant (GR) soybean cultivars have been rapidly adopted by farmers in Argentina and in other countries in the world. The high rate of adoption of this technology seems to be based on the simplicity of use provided by a single herbicide (glyphosate), its high efficacy to control many weeds and, the low costs of the technology relative to that used in conventional crops. During 2001–2002, 2002–2003 and 2003–2004 soybean growing seasons, field surveys and field experiments were performed with the aim of studying the effect of different glyphosate management strategies on the diversity of soybean weed communities, weed control, individual survival, fecundity and crop yield. In addition, the emergence pattern of three important weeds, Digitaria sanguinalis, Cyperus rotundus and Anoda cristata, was also studied. Both field surveys and field experiments were carried out on no-till soybean crops sown immediately after wheat or barley harvest (double cropped system). Experiments were set up in commercial soybean crops and consisted of different times of a single glyphosate application, two glyphosate applications and also the application of glyphosate plus a residual herbicide imazethapyr. A. cristata, D. sanguinalis, Stellaria media, Chenopodium album and Cyperus sp. were the most prevalent weeds recorded at pre-harvest of the soybean crops, showing regional constancy higher than 80% in both years. In three out of four field experiments, crop yield was not increased when glyphosate was applied twice compared with a single application of the herbicide. In addition there was a lower negative effect on weed species richness when glyphosate was applied once during the crop cycle than with two applications of glyphosate or glyphosate plus imazethapyr. D. sanguinalis escaped the glyphosate early treatment because of the long weed emergence period, while A. cristata and C. rotundus survived treatments due to their high individual tolerance. The results suggest that it is possible to manage glyphosate application to get high crop yield with a low impact on weed diversity, depending on the weed species and their abundance.     

Impact of crop and nutrient management on crop growth and yield,nutrient uptake and content in rice

Paddy and Water Environment - System of rice intensification (SRI) together with appropriate nutrient management holds promise in increasing rice productivity with micronutrient enriched grains....     

氮磷钾配施对大豆产量的影响

在两点进行"3414"肥料试验,通过肥料效应函数拟合,研究了氮磷钾肥不同比例配施对大豆产量的影响。结果表明:氮磷钾肥配施能够显著提高大豆产量,单株粒数受磷施用量影响较大,百粒重受氮磷施用量影响较大。推荐的高产施肥量为:N75～85kg/hm2、P2O565～70kg/hm2、K2O45～55kg/hm2,比例为:N:P2O5:K2O=1.60:1.35:1;经济施肥量为:N65～75kg/hm2、P2O545～50kg/hm2、K2O30～40kg/hm2,比例为:N:P2O5:K2O=2:1.36:1。     

The implications of land preparation, crop establishment method and weed management on rice yield variation in the rice-wheat system in the Indo-Gangetic plains

The implications of adopting alternative seeding methods for rice and wheat establishment were examined at three geographically separate sites in the rice-wheat system of the Indo-Gangetic plains, across northern India. Rice yields in cultivated plots, established by either wet or dry seeding methods, were evaluated in comparison to yields from zero-tillage plots and under conventional transplanting methods. In the same trials, the effects of crop establishment methods in wheat were assessed both on wheat yields and rice yields. Rice crop establishment methods markedly influenced the emerging weed flora and attainable yields were measured in relation to intensity of weed management. Over four years, average rice grain yields in the absence of weed competition were greatest (6.56 t ha⁻¹) under wet seeding (sowing pre-germinated rice seed on puddled soil), and similar to those from transplanted rice (6.17 t ha⁻¹) into puddled soil, and dry seeded rice after dry soil tillage (6.15 t ha⁻¹). Lowest yields were observed from dry seeded rice sown without tillage (5.44 t ha⁻¹). Rice yield losses due to uncontrolled weed growth were least in transplanted rice (12%) but otherwise large (c. 85%) where rice had been sown to dry cultivated fields or to puddled soil, rising to 98% in dry seeded rice sown without soil tillage. Weed competition reduced multiple rice yield components, and weed biomass in wet seeded rice was six-fold greater that in rice transplanted into puddled soil and twice as much again in dry seeded rice sown either after dry tillage or without tillage. Wheat grain yields were significantly higher from crops sown into tilled soil (3.89 t ha⁻¹) than those sown without tillage (3.51 t ha⁻¹), and also were elevated (5% on average) where the soil had been dry cultivated in preparation for the previous rice crops rather than puddled. The method of wheat cultivation did not influence rice yield. Soil infiltration rates in the wheat season were least where the land had been puddled for rice (1.52 mm h⁻¹), and greater where the soil had been dry-tilled (2.63 mm h⁻¹) and greatest after zero-tillage (3.54 mm h⁻¹).These studies demonstrated at research managed sites across a wide geographic area, and on farmers’ fields, that yields of dry seeded rice sown after dry cultivation of soil were broadly comparable with those of transplanted rice, providing weed competition was absent. These results support the proposition that direct seeding of rice could provide an alternative to the conventional practice of transplanting, and help address rising costs and threats to sustainability in the rice-wheat rotation. Further, analysis of patterns of long-term rainfall data indicated that farmers reliant on monsoon rainfall could prepare fields for dry direct seeded rice some 30 days before they could prepare fields for either transplanting or seeding with pre-germinated seed. Dry, direct seeding of rice contributes a valuable component of an adaptive strategy to address monsoonal variability that also may advance the time of wheat establishment and yield. Whilst the results illustrate the robustness, feasibility and significant potential of direct seeded rice, they also highlight the critical nature of effective weed control in successful implementation of direct seeding systems for rice.     

借鉴日本的土壤培肥管理成果提高大豆品质和产量

本文通过借鉴日本大豆氮元素、磷元素、钾元素,矿物质元素等化学肥料,农家肥以及土壤的pH值调整等的培肥管理技术,阐述了重视土壤的培肥管理,对提高我国大豆品质和产量的重要性。     

Interaction between cultivar and crop management effects on winter wheat diseases, lodging, and yield

The breeding of winter wheat (Triticum aestivum L.) for resistance to major fungal diseases has been a priority over the last 15 years in France. During this period, integrated low-input strategies have been developed for winter wheat, to cope with falling grain prices and growing environmental concerns. We investigated the interactions between genotype and management for disease and lodging intensities, and analysed their effects on yield within an integrated crop management (CM) context.

A multi-environment experimental network (13 locations, studied in three seasons, between 1999–2000 and 2001–2002) comprising several combinations of cultivars and CM systems was carried out. Four rule-based CM plans were defined, with a decrease in input level from CM1 (a high-input CM plan designed to maximise the yield of a given cultivar) to CM4 (a low-input system with no fungicide protection, no plant growth regulator applications, a sowing density 40% lower than for CM1, and 90 kg ha⁻¹ less N fertiliser than for CM1). Cultivars were clustered into three groups (cultivar type (CT) CT1–CT3), according to their scores for resistance to diseases, for the analysis of yield, whereas the resistance cultivar rating (CR) for each disease and for lodging was considered for the analysis of disease and lodging intensities.

For all diseases, CM had a significant effect (P<0.0001), with disease intensity increasing from CM1 to CM4, whereas CR had a negative effect (P<0.005). An interaction between CR and CM was also detected for all diseases (P<0.005) except eyespot. Lodging intensity decreased significantly from CM1 to CM4 (P<0.0001), and significant increases in lodging resistance score (P<0.0001) were not associated with a genotype by management interaction.

Lastly, yield was significantly affected by CM (P<0.0001), CT (P<0.0003), and CM by CT interaction (P=0.0023). Cultivar ranking differed as a function of CM for yield, demonstrating that breeding programs focusing on cultivar evaluation in high-input environments do not result in the selection of cultivars suited to low-input environments.     

Improving crop yield and N uptake with long-term straw retention in two contrasting soil types

Retention and/or reincorporation of plant residues increases soil organic nitrogen (N) levels over the long-term is associated with increased crop yields. There is still uncertainty, however, about the interaction between crop residue (straw) retention and N fertilizer rates and sources. The objective of the study was to assess the influence of straw management (straw removed [S_Rem] and straw retained [S_Ret]), N fertilizer rate (0, 25, 50 and 75 kg N ha⁻¹) and N source (urea and polymer-coated urea [called ESN]) under conventional tillage on seed yield, straw yield, total N uptake in seed + straw and N balance sheet. Field experiments with barley monoculture (1983-1996), and wheat/barley-canola-triticale-pea rotation (1997-2009) were conducted on two contrasting soil types (Gray Luvisol [Typic Haplocryalf] loam soil at Breton; Black Chernozem [Albic Argicryoll] silty clay loam at Ellerslie) in north-central Alberta, Canada. On the average, S_Ret produced greater seed yield (by 205-220 kg ha⁻¹), straw yield (by 154-160 kg ha⁻¹) and total N uptake in seed + straw (by 5.2 kg N ha⁻¹) than S_Rem in almost all cases in both periods at Ellerslie, and only in the 1997-2009 period at Breton (by 102 kg seed ha⁻¹, 196 kg straw ha⁻¹ and by 3.7 kg N ha⁻¹) for both N sources. There was generally a considerable increase in seed yield, straw yield and total N uptake in seed + straw from applied N up to 75 kg N ha⁻¹ rate for both N sources at both sites and more so at Breton, but the response to applied N decreased with increasing N rate. The ESN was superior to urea in increasing seed yield (by 109 kg ha⁻¹), straw yield (by 80 kg ha⁻¹) and total N uptake in seed + straw (by 2.4 kg N ha⁻¹) in the 1983-1996 period at Breton (mainly at the 25 and 50 kg N ha⁻¹ rates). But, urea produced greater straw yield (by 95 kg ha⁻¹) and total N uptake in seed + straw (by 3.3 kg N ha⁻¹) than ESN in the 1983-1996 period at Ellerslie. The N balance sheets over the 1983-2009 study duration indicated large amounts of applied N unaccounted for (ranged from 740 to 1518 kg N ha⁻¹ at Breton and from 696 to 1334 kg N ha⁻¹ at Ellerslie), suggesting a great potential for N loss from the soil-plant system through denitrification and/or nitrate leaching, and from the soil mineral N pool by N immobilization. In conclusion, the findings suggest that long-term retention of crop residue may gradually improve soil productivity. The effectiveness of N source varied with soil type.     

Intraspecific responses in crop growth and yield of 20 soybean cultivars to enhanced ultraviolet-B radiation under field conditions

Field studies were conducted to determine the potential for intraspecific responses in crop growth and grain yield of 20 soybean cultivars to enhanced ultraviolet-B (UV-B, 280–315 nm) radiation. The supplemental UV-B radiation was 5.00 kJ m⁻², simulating a depletion of 20% stratospheric ozone at Kunming (25°N, 1950 m). Out of the 20 soybean cultivars tested, 17 and 15 showed significant change in plant height at 80 DAP (days after planting) and ripening stages, respectively. Sensitivity in plant height was greater at 80 DAP than at ripening. The plant height of 3 cultivars increased, and that of 17 cultivars decreased. Under UV-B radiation, LAI (leaf area index), biomass and grain yield decreased, respectively. The greatest percent decrease was 95.7, 93.9 and 92.8, respectively. RI (response index) was the sum of percent change in plant height at ripening, LAI, biomass and grain yield. The results showed that all 20 soybean cultivars had a negative RI, indicating inhibition by UV-B radiation on soybean growth. The RI of 6 tolerant cultivars was higher than −163.1 and 5 out of 6 originated from south China (low latitude). The RI of the most tolerant cultivars, Yunnan 97801, was −72.4. Meanwhile, the RI of 5 sensitive cultivars was lower than −256.9 and 4 out of the 5 originated from north China (high latitude). The RI of the most sensitive cultivar, Huanxianhuangdou, was −295.7. These UV-B tolerant cultivars identified in this study might be useful in breeding programs.     

Effect of cultivar, row spacing, and weed management on weed biomass, potato yield, and net crop value

Research was conducted to quantify the effects of potato cultivar, row spacing, and weed control treatments on weed biomass, crop yield, and net crop value. Cultivars evaluated included Russet Burbank, Russet Norkotah, Goldrush, Dark Red Norland, Snowden, and Atlantic. Inter-row spacings of 76 and 91 cm with an intra-row spacing of 30 cm were evaluated in 1996 and 1997. Weed control treatments included a herbicide tank-mix of metribuzin and metolachlor, cultivation, and a hilling-only control. Common lambsquarters and total weed biomass were greater in the 76-cm row spacing than in the 91-cm row spacing across all cultivars in 1996 and 1997. In 1997, chemical control resulted in less weed biomass than both the hilling-only and cultivation treatments. Total marketable yield was greater in the 91-cm row spacing than in the 76-cm row spacing across cultivars in 1996, but was similar across row spacings in 1997. Net crop value was greater across cultivars in the 91-cm row spacing than in the 76-cm row spacing in 1996. Reduced weed biomass in 1996 and 1997, coupled with greater total marketable yield and net return in 1996, indicated that the 91-cm row spacing was the optimal row spacing for Russet Burbank, Goldrush, Russet Norkotah, Snowden, and Atlantic cultivars in 1996 and 1997. Similar yields and net crop value among weed control treatments in 1996 and 1997 indicated that cultivation and possibly even hilling-only areas within fields can be viable alternatives to herbicide use.     

Root growth,soil water variation,and grain yield response of winter wheat to supplemental irrigation

Water shortage threatens agricultural sustainability in the Huang-Huai-Hai Plain of China. Thus, we investigated the effect of supplemental irrigation (SI) on the root growth, soil water variation, and grain yield of winter wheat in this region by measuring the moisture content in different soil layers. Prior to SI, the soil water content (SWC) at given soil depths was monitored to calculate amount of irritation water that can rehydrate the soil to target SWC. The SWC before SI was monitored to depths of 20, 40, and 60 cm in treatments of W20, W40, and W60, respectively. Rainfed treatment with no irrigation as the control (W0). The mean root weight density (RWD), triphenyl tetrazolium chloride reduction activity (TTC reduction activity), soluble protein (SP) concentrations as well as catalase (CAT), and superoxide dismutase (SOD) activities in W40 and W60 treatments were significantly higher than those in W20. The RWD in 60–100 cm soil layers and the root activity, SP concentrations, CAT and SOD activities in 40–60 cm soil layers in W40 treatment were significantly higher than those in W20 and W60. W40 treatment is characterized by higher SWC in the upper soil layers but lower SWC in the 60–100-cm soil layers during grain filling. The soil water consumption (SWU) in the 60–100 cm soil layers from anthesis after SI to maturity was the highest in W40. The grain yield, water use efficiency (WUE), and irrigation water productivity were the highest in W40, with corresponding mean values of 9169 kg ha^?1, 20.8 kg ha^?1 mm^?1, and 35.5 kg ha^?1 mm^?1. The RWD, root activities, SP concentrations, CAT and SOD activities, and SWU were strongly positively correlated with grain yield and WUE. Therefore, the optimum soil layer for SI of winter wheat after jointing is 0–40 cm.     

Simulation for response of crop yield to soil moisture and salinity with artificial neural network

In saline fields, irrigation management often requires understanding crop responses to soil moisture and salt content. Developing models for evaluating the effects of soil moisture and salinity on crop yield is important to the application of irrigation practices in saline soil. Artificial neural network (ANN) and multi-linear regression (MLR) models respectively with 10 (ANN-10, MLR-10) and 6 (ANN-6, MLR-6) input variables, including soil moisture and salinity at crop different growth stages, were developed to simulate the response of sunflower yield to soil moisture and salinity. A connection weight method is used to understand crop sensitivity to soil moisture and salt stress of different growth stages. Compared with MLRs, both ANN models have higher precision with RMSEs of 1.1 and 1.6 t ha⁻¹, REs of 12.0% and 17.3%, and R² of 0.84 and 0.80, for ANN-10 and ANN-6, respectively. The sunflower sensitivity to soil salinity varied with the different soil salinity ranges. For low and medium saline soils, sunflower yield was more sensitive at crop squaring stage, but for high saline soil at seedling stage. High soil moisture content could compensate the yield decrease resulting from salt stress regardless of salt levels at the crop sowing stage. The response of sunflower yield to soil moisture at different stages in saline soils can be understood through the simulated results of ANN-6. Overall, the ANN models are useful for investigating and understanding the relationship between crop yield and soil moisture and salinity at different crop growth stages.     

红壤旱地春大豆品种的产量,品质及矿质营养的基因差异

在江西红壤旱地底施氮磷钾肥条件下,６个不同生育期品种的产量均可达到１５００ｋｇ／ｈｍ＾２以上,在气候条件较好的１９９７年,分别达到１７００－２３５０ｋｇ／ｈｍ＾２,产量高低及主要经济性状随品种生育期长短而异,与对照相比,增产率为２．５４％－３５．５３％,主要农艺性状亦存在差异;生育期长的品种比生育期短的品种蛋白质含量低、油分含量高,但蛋白质,油分之和均超过６５％。早熟品种８９０５－１不但产量高出中     

自然降水与夏大豆生长发育关系分析

利用安徽省濉溪县1970 2004年大豆统计产量和相应的实测气象数据进行了统计分析。结果表明:濉溪县大豆幼苗期和鼓粒期的降水量、花荚期和全生育期的雨日与气象产量呈显著直线相关,大豆生长季节降水及其时空分布是造成实际产量围绕生产水平线波动的主要原因。大豆生育期内适宜降水为:降水量380~540mm,雨日24~34d。濉溪县大豆生育期内降水适中,涝多于旱。当耕层土壤含水量低于16%,预计5~7d内又无雨量较大的降水时,要及时灌溉浇水。     

江西省红壤丘陵春大豆高产配套栽培技术

春大豆在江西是一种增加复种指数改进轮作、间、套多熟制的主要作物 ,但由于品种和栽培技术的原因 ,产量比较低 ,影响了我省春大豆的发展。本文在九·五国家重点推广项目“南方红黄壤大豆良种及配套技术推广”五年多的实施过程中 ,根据高产试验、示范和高产攻关中出现的一批 3 0 0 0kg/hm2 以上的高产典型经验 ,总结提出了一套江西省红壤旱地春大豆高产配套栽培技术。     

The effects of nitrogen and iron fertilization on growth,yield and fertilizer use efficiency of soybean in a Mediterranean-type soil

Poor seed yield of soybean in Mediterranean-type environments may result from insufficient iron (Fe) uptake and poor biological nitrogen (N) fixation due to high bicarbonate and pH in soils. This study was conducted to evaluate the effects of N and Fe fertilization on growth and yield of double cropped soybean (cv. SA 88, MG III) in a Mediterranean-type environment in Turkey during 2003 and 2004. The soil of the experimental plots was a Vertisol with 176 g CaCO₃ kg⁻¹ and pH 7.7 and 17 g organic matter kg⁻¹ soil. Soybean seeds were inoculated prior to planting with commercial peat inoculants. N fertilizer rates were 0, 40, 80, and 120 kg N ha⁻¹ of which half was applied before planting and the other half at full blooming stage (R2). Fe fertilizer rates were 0, 200 and 400 g Fe EDTA (5.5% Fe and 2% EDTA) ha⁻¹. It was sprayed as two equal portions at two trifoliate (V2) and at five trifoliate stages (V5). Plants were sampled at flower initiation (R1), at full pod (R4) and at full seed (R6) stages. Application of starter N increased biomass and leaf area index at R1 stage whereas Fe fertilization did not affect early growth parameters. N application continued to have a positive effect on growth parameters at later stages and on seed yield. Fe fertilization increased growth parameters at R4 and R6 stages, and final seed yield in both years. This study demonstrated an interactive effect of N and Fe fertilization on growth and yield of soybean in the soil having high bicarbonate and pH. There was a positive interaction between N and Fe at the N rates up to 80 kg N ha⁻¹. However, further increase in N rate produced a negative interaction. Fertilization of soybean with 80 kg N ha⁻¹ and 400 g Fe ha⁻¹ resulted in the highest seed yield in both years. We concluded that application of starter and top dressed N in combination with two split FeEDTA fertilization can be beneficial to improve early growth and final yield of inoculated soybean in Mediterranean-type soils.     

Effect and interaction of crop management factors on the glycoalkaloid concentration of potato tubers

Summary Potato tuber glycoalkaloid content was measured in response to nitrogen fertilizer rate, storage temperature, length of storage period and cultivar. Cvs Gemchip, Norchip and Russet Burbank were grown with applied nitrogen fertilizer rates of 0, 168 or 336 kg/ha and then stored at either 4.4 or 10°C. Total glycoalkaloid content was determined one month before harvest, at harvest, after three months of storage and after nine months of storage. Higher rates of nitrogen, higher storage temperature and a period of storage all resulted in significantly (P<0.05) higher concentration of glycoalkaloids. The cv Norchip had higher glycoalkaloids than cvs Gemchip or Russet Burbank. Only the storage period had more influence than the environment (difference between years). Significant (P<0.05) two-way interactions were detected for year x cultivar, year x nitrogen, storage period x cultivar and nitrogen x cultivar. Most interactions were due to the unique responses of cultivars.     

密度与施肥对春大豆农艺性状及产量的影响

以吉育37为试材研究了种植密度和施肥量对大豆株高、叶面积指数、干物质积累和产量的影响.结果表明:随着密度的增加,株高、叶面积指数呈现上升的趋势,干物质积累呈现下降的趋势;随着施肥量的增加,株高、叶面积指数和干物质积累都呈现上升的趋势;随着密度的增加,大豆产量呈现先上升后下降的趋势;随着施肥量的增加,大豆产量呈现上升的趋势.在密度为19×104株/hm2、施肥量为200 kg/hm2时,产量最高.     

Nutrient use efficiencies and crop responses to N, P and manure applications in Zimbabwean soils: Exploring management strategies across soil fertility gradients

The spatial variability in crop yields commonly observed in smallholder farms of sub-Saharan Africa is often caused by gradients of declining soil fertility with increasing distance from the homestead. This heterogeneity means that recommendations based on regional soil surveys are of limited value. The variability in soil qualities within farms must be considered when designing management strategies, and their feasibility analysed by integrating results at the farm livelihood scale. For this purpose, we have developed the model FARMSIM, a dynamic bio-economic model for analysis and exploration of trade-offs in resource and labour allocation in heterogeneous smallholder farms. Focusing on farm-scale strategies, the approach to simulation of soil and crop processes in FARMSIM (the sub-model FIELD) is designed to be simple, but to keep the necessary degree of complexity to capture heterogeneity in resource use efficiencies. To test our approach, the sub-model FIELD was calibrated against chronosequences of woodland clearance in three agroecological zones of Zimbabwe (with soil textures of 3, 10, 35% clay), and used to simulate: (i) the creation of soil fertility gradients, and (ii) different strategies of N, P and manure applications to maize and soyabean rotations in homefields and outfields of smallholder farms on clayey and sandy soils. The results of the simulation of management strategies were tested against on-farm experimental data from Murewa, Zimbabwe. The model produced satisfactory predictions (r²: 0.6–0.9) of long-term changes in soil organic C, of crop responses to N and P and of nutrient use efficiencies across a wide range of yields and different field types. This demonstrated the broad applicability of the model despite the sparse data required for initialisation. However, the model results were less accurate in predicting crop responses to N and P applications in the outfields on sandy soils. Experimental evidence indicated yield limitation by Ca and Zn deficiencies in highly depleted outfields on sandy soils, which were not included mechanistically in the current version of FIELD. Repeated applications of 16 t ha⁻¹ year⁻¹ of manure allowed larger responses to applied N and P after 3 years of experimentation; such a corrective effect of manure was simulated to be due to improved N and P recovery efficiencies in the model. In combination with the experimental data, the simulation results suggested that soil fertility gradients affect nutrient use efficiencies, operating mostly on the efficiencies of nutrient capture rather than conversion. A typology of fields according to the type of management interventions needed is introduced, based on a generic application of FIELD with this parameterisation.     

锰对大豆氮代谢相关指标及产量品质的影响

以大豆品种垦农4号为材料,在大田小区试验的条件下,研究EDTA-Mn浸种和在初花期（R1期）叶面喷施对大豆叶片可溶性蛋白、硝态氮、游离氨基酸含量、硝酸还原酶活性及产量品质的影响。结果表明,无论在浸种处理（A）还是叶面喷施处理（B）中,中浓度锰(即A3 1.54g/L和B3 20g/L)处理对大豆叶片可溶性蛋白、硝态氮、游离氨基酸含量及硝酸还原酶活性均有一定的促进作用,但随着生育期的推进,浸种处理对各指标影响效果逐渐减弱。同时,中浓度的锰处理有利于大豆单株粒数、荚数和单株产量的提高,从而达到大豆增产的目的,且能够使大豆的蛋脂总量明显提高。高浓度的锰(即A4 15.4g/L或B4 60g/L)处理则对上述指标起抑制作用。