Effects of straw mulch on mungbean yield in rice fields with strongly compacted soils

In rice-based lowland areas in the Mekong region, the lack of full irrigation water availability for post-rice legume crops and the poor soil physical and chemical conditions are major constraints for development of sound rice/legume double cropping system. In order to improve legume productivity, use of rice straw mulch and various crop establishment methods were examined in two series of mungbean experiments in Cambodia where soils were coarse and strongly compacted. In one set of experiments conducted at four locations in the first year the effect of straw mulch, planting method (manual vs seed drill) and tillage method (conventional vs no-till) was examined. Another set of experiments were conducted in the second year at three locations with four levels of mulch under two planting densities. On average in year 1, mulching of rice straw at 1.5 t/ha increased mungbean crop establishment from 72 to 83%, reduced weed biomass from 164 to 123 kg/ha and increased yield from 228 to 332 kg/ha. Mulch was effective in conserving soil moisture, and even at maturity the mulched area had on average 1% higher soil moisture content. The amount of mulch between 1 and 2 t/ha did not show consistent effects in year 2, partly because some mulch treatments resulted in excessive soil moisture content and were not effective. Rice straw mulch had a significant effect on mungbean yield in 6 out of the 7 experiments conducted in two years, and mean yield increase was 35%. This yield advantage was attributed to better crop establishment, improved growth and reduced weed pressure, but in some cases only one or two of these factors were effective. On the other hand, planting method, tillage method and planting density had only small effects on mungbean yield in most experiments. Only in one location out of four tested, the no-till treatment produced significantly higher yield than the conventional method. Seed drill produced similar mungbean establishment and grain yield to the manual planting suggesting that the planter can be used to save the labour cost which is increasing rapidly in the Mekong region. Maximum root depth varied little with mulch or planting density, and was shallow (<20 cm) in all three locations where this character was determined. It is concluded that while rice straw mulch increased yield of mungbean following rice, the inability of mungbean roots to penetrate the hard pan is a major constraint for development of a sound rice/mungbean cropping system in the lowlands with compacted soils.     

Whole farm implications on the application of variable rate technology to every cropped field

In the last 10 years precision agriculture has evolved and it is now possible to manage cropping inputs at the sub field scale. However, the expected return generated by these management practices varies with the amount and predictability of the spatial variation in crop yield across the field and may vary from field to field across the farm. We analysed the spatial variation of crop yield from 20 fields totalling 2832 ha from a 5200 ha farm in Western Australia at the field and the sub field scale to determine the economic value of introducing variable rate management (VRT) strategies to fields across the entire farm. In this case study, 6 out of 20 fields generated an additional economic payoff of AU$15/ha when managed with VRT over uniform management. Sensitivity analysis found that the starting levels of soil fertility were an important driver of the payoff for managing a field with VRT. If starting soil fertility was low and uniform across the field, then no fields generated an economic return of more than AU$7.00/ha when managed with VRT. Other factors, including commodity price, fertiliser price, amount of variation in crop yield within the field moderately increased the value of adopting VRT across fields within farm the value of VRT increased if fertiliser budgets were constrained, particularly if the yield distribution of the field was negatively skewed. While VRT does add value to many fields across the farm, the gains are small and the technology must be implemented cheaply for it to be viable.     

浙江金华地区水稻土养分供应能力研究

 自1997年早稻开始，在浙江省金华市农业科学研究所试验区稻田设立了监测水稻土生产力及肥力变化的长期肥料定位试验，并在试验区周围10 km范围内选择了21户农民的稻田进行相应的监测试验。试验区内农户间稻田土壤的养分供应能力相差很大，氮供应能力变化于49~116 kg/hm2，磷供应能力变化于13~32 kg/hm2，钾供应能力变化于68~183 kg/hm2。农民常规施肥区的氮肥利用效率很低，氮表观回收率的平均值为14%~26%，氮肥农业效率平均值为4.6~8.2，且农户之间、早晚稻之间均存在较大差异。肥料定位试验结果表明，在连续种植水稻条件下，缺肥区土壤相应的有效养分消耗很快。与NPK全肥区比较，NP区从第2季水稻起，NK区从第3季水稻起，即开始出现减产。针对当地农民现行养分管理的实际情况，就水稻系统发展适地养分综合管理新技术进行了讨论。     

The effect of chloride fertilization on blackspot susceptibility and other quality characteristics and on yield of potato

Summary Trials were carried out in two years on a sandy loam and on a heavy clay soil with two cultivars to examine the potential of chloride fertilization as a tool to reduce blackspot susceptibility of potatoes and to investigate other effects on yield and quality. Blackspot susceptibility was significantly reduced in cv. Marijke, but not in cv. Bintje as a result of increasing doses of applied chloride from 0 to 400 kg ha1. Dry matter concentration, assessed as under-water weight, was reduced by chloride in both cultivars at the two locations. Fry colour of French fries was improved by chloride. Applying 400 kg ha⁻¹ Cl⁻ to both soil types decreased net tuber yield >35 mm of cv. Bintje but not of cv. Marijke. Chloride caused slower emergence, retarded crop development and less stems per plant on the sandy loam soil but not on the heavy clay soil.     

Estimation of lucerne yield stability for enabling effective cultivar selection under rainfed conditions

Evaluation of crop and forage yield stability is of increasing relevance in the context of current and recent environmental changes but, in contrast to other field crops, there are no published systematic analyses among forage crops in Europe. A study of stability performance was conducted with 13 Czech cultivars of lucerne at four locations over a 2‐year period with the following aims: (a) to evaluate yield stability of varieties across different environments and (b) to calculate measurable benefits of variety selection in relation to the specific environment. The cultivar Vlasta was identified as the highest yielding cultivar (annual yield 16.0 t DM/ha), whereas the lowest yielding cv. Magda, Tereza and Oslava averaged around 14.9 t DM/ha. Effect of genotype × environment interaction (G × E) was two times higher than for genotype alone. Additive main effects and the multiplicative interaction (AMMI) model showed that the highest yielding cultivars may not be stable across environments. This study demonstrated further that significant yield improvement could be detected, even among a relatively homogenous group of domestic cultivars, and this was driven mainly by site productivity: the improvement was +10% in low‐yielding sites, compared with +3% in high‐yielding sites. Results highlight that advanced agronomy should also consider stability parameters such as AMMI stability value or superiority measures for forage crops in response to the challenges associated with climate change.     

前茬小麦不同耕作方式对土壤含水量和夏玉米产量的影响

2009年采用大区试验,在前茬小麦免耕和耕作方式下,自然条件下对夏玉米田进行土壤含水量变化及夏玉米产量比较研究。结果表明,2009年夏玉米整个生育期降雨量为339.5 mm,前茬小麦两种耕作方式在不同时期不同土层的土壤平均含水量都在13%以上,并且两种方式不同土层平均含水量差异不显著;在夏玉米需水高峰期,相应的有效降水使土壤含水量能够满足夏玉米生长的需要。前茬小麦免耕和耕作下玉米平均产量分别为7 839.2、8 074.5 kg/hm2,差异不显著。因此,前茬小麦免耕可节省劳动量,防止水土流失,保护土壤结构,消除犁底层对作物根系生长与养分吸收的影响。     

Management of Soil Salinity and Alkalinity Problems in India

SUMMARY

Like the problem of salt-affected soils afflicting many other countries with arid and semi-arid climates, these lands occupy about 8.6 M ha in India out of which 3.5 M ha are in canal commands, commonly referred to as man made or wet deserts. Starting from the early systematic work of Dr. Leather about a century ago, real impetus to development and application of reclamation technologies has occurred in the post independence period, especially the seventies. Salt-affected soils are grouped into saline and alkali/sodic soils on the considerations of soil management and crop responses. Out of the 3.4 M ha of alkali lands in Indo-Gangetic Plains, about 1.0 M ha has been reclaimed by the hydro-chemical technology. Application of amendments like gypsum, equivalent to 50% gypsum requirement, to the surface 15-cm soil only was enough to start cropping with rice. Light and frequent irrigation are ideal for upland crops. Application of higher doses of nitrogen in splits to compensate for volatilization losses, organic matter additions through green manure to increase reclaiming action, skipping phosphorus application in the initial years and the application of zinc to each crop were some of the emerging recommendations. Application of low-grade pyrites also gave encouraging results in calcareous soils. Feasibility of drainage has been successfully demonstrated in 1980s for the quicker rehabilitation of saline and waterlogged soils. Provision for subsurface drains at 1.5–2.0 m depth and 50–75 m spacing in alluvial soils and 12–24 m interval in vertisol was sufficient for facilitating growing crops within 2–3 years on lands lying barren for considerable period. However, technological, economic, social, and political considerations are the major bottlenecks for large-scale amelioration of saline soils, in addition to the safer disposal of drainage waters. Strategies worked out for successful crop production on saline soils after drainage include initial leaching management (minimizing water requirement for leaching by synchronizing with monsoon rains, etc.), proper selection of crops/cultivars, irrigation (method, controlled frequency for enhancing water-table contribution, canal water use during the initial stages including presowing for conjunctive use with drainage waters) and cultural practices (furrow planting, increasing seed rate and fertility management). Some of the future issues for combating salinity and also preventing further land degradations in India are also highlighted.     

Effects of gypsum,sulfur, terraclor and terraclor super-x for potato scab control

An investigation was made to determine possible effects of gypsum and sulfur for control of common scab of potato [Streptomyces scabies (Thaxt.) Waksman and Henrici] in a highly buffered calcareous soil. This investigation included a comparison of the effectiveness of gypsum and sulfur with Terraclor and Terraclor Super-X. Both gypsum and sulfur reduced potato scab and measurements indicate that change of soil pH was slight (0.1–0.4 pH reduction). Band applications of sulfur in the sulfate (gypsum) or elemental form were effective at 600 lbs/A (672.5 Kg/ha) but not at lower rates. The weight of tubers thrown out of grade with scab was reduced by 53% with the effective sulfur rate. Treatment effects of gypsum (600 lb S/A-672.5 Kg/ha) were not significantly different from sulfur dust (600 lb/A-672.5 Kg/ha), Terraclor or Terraclor Super-X (both at 25.0 lb PCNB/A-28.0 Kg/ha). Tissue analyses of tuber peelings showed a significant reduction in calcium from treatments involving sulfur and gypsum, indicating that calcium levels in tuber peelings were positively correlated with scab susceptibility.     

Effect of K fertilization on yield and leaf nutrient concentrations of potatoes grown on a sandy soil

A large percentage of winter and spring potatoes (Solanum tuberosum, L.) grown in the USA is produced in northeast Florida (NEF) on sandy soils with low cation exchange capacity. Maintaining adequate K nutrition is a major concern. A study was conducted on an Elzey fine sand (sandy, siliceous, hyperthermic Typic Humaquept) in NEF to relate yield and leaf K to soil and fertilizer K levels. In 1981, Mehlich-I soil K in the 0–15 cm depth averaged 73 mg/kg. Yields of 35 t/ha were obtained without any K fertilization and no response to K sidedressed at rates up to 70 kg/ha was obtained. In the following three years, soil K prior to fertilization was < 40 mg/kg. In 1982 and 1983, significant differences in yield were obtained as a result of K fertilization at planting at rates up to 186 kg/ha. In 1984, no yield differences were obtained with K fertilizer rates ranging from 94 to 280 kg/ha. Differences in maximum tuber yields from year to year were related to the number of growing-degree days accumulated between planting and harvest. Yield-leaf K relationships for leaf samples taken late in the season showed that the critical leaf K concentration for 35 t/ha yields was no more than about 20 g/kg; that for yields approaching 40 t/ha was no more than about 45 g/kg. The results of this study indicated that current K fertilizer recommendations are higher than necessary for the yields being obtained by most NEF potato growers.     

Productivity Enhancement in the Salt-Affected Lands of Joint Satiana Pilot Project Area of Pakistan

SUMMARY

Salt-affected lands are common in Pakistan and cover an area of 6.8 million ha; i.e., about one-third of the total cultivated area. Reduction in yield of different crops due to salinity and waterlogging is sometimes more than 60%, and annual losses under rice-wheat rotation have been calculated at Rs. 10 billion (US$ 166 million). Other adverse effects of salinity on the community are very large and about 16 million people are affected directly by the hazards of salinity and waterlogging. Average farmers in Satiana project area (38 villages) have 4–5 ha of land, of which approximately 55% are salt-affected. This area is equipped with a modern tile drainage system but it has not shown the expected impact on the rehabilitation of salt-affected soils. Farmers of Satiana area are poor and depend on off-farm activities for their livelihood. Nevertheless, they are keen to improve their soils. A productivity enhancement program was launched in the affected area, where saline agriculture was successfully demonstrated to restore the productivity of salt-affected lands and about 405 ha were successfully rehabilitated by planting salt-tolerant trees, forage shrubs, crops and applying gypsum to improve the soil conditions. Some relevant research studies used to develop the saline agriculture strategy have also been discussed.     

Simulating grain yield and plant development of ratoon grain sorghum over diverse environments

Crop simulation may provide an inexpensive means to evaluate the feasibility of different cropping practices to optimize productivity and profitability. One practice, ratoon-cropping, may increase productivity and reduce per-unit production costs associated with conservation tillage farming systems in tropical and subtropical regions. sorkam, a dynamic plant growth model for grain sorghum [Sorghum bicolor (L.) Moench], was used to evaluate the potential of rainfed ratoon grain sorghum over diverse climatic regions of Texas. Eleven independent data sets collected in the U.S.A. from sites in Georgia and Texas were used to determine the model's accuracy. The model produced realistic estimates of grain yield for planted, ratoon, and combined (planted + ratoon) crops. Simulated grain yields usually were within 25% of the observed yield for the planted, ratoon, and combined crops with cultivars that produced the highest ratoon grain yield at each location. Ratoon grain yield results of multi-year simulations (10–30 years) from 14 locations over the eastern half of Texas using historic, location-specific, meteorological data indicated that the probability of obtaining ratoon grain yield > 3.0 Mg/ha was confined to the upper coastal plain region of Texas. The area best suited for rainfed ratoon grain sorghum appeared to be confined south and east of a line running from west of Corpus Christi to Beeville to College Station to west of Center, Texas. Use of crop models can play an important role in identifying strengths and weaknesses of potential cropping systems when used in combination with historical climatic data and/or computer weather generators.     

Decadal changes in the rice-cropping system in the Ayeyarwady Delta using a large archive of satellite imagery from 1981 to 2020

In the last 40 years, the rice-cropping system has considerably changed in the Ayeyarwady Delta. The large archive of satellite imagery provides a history of how land and water resource managements have changed in the face of growing populations, resource demand, and climate change. This study aimed to assess the decadal changes in the rice-cropping system in the Ayeyarwady Delta by using the large archive of satellite imagery for the last 40 years (1981???2020). The long-term NDVI dataset provided various information on rice cultivation. Signal processing techniques were used to detect on the historical changes in the rice-cropping system, and the impact of climate change was assessed by using trend analysis. Until the 1980s, single-cropping of summer rice was dominant in the Delta. To enhance the grain yield of rice, the irrigation facilities were introduced in 1992 under an initiative of the Myanmar government. As a result, the annual cropping intensities increased from 1.087?±?0.390 in the 1980s to 1.422?±?0.499 in the 2010s. The information on historical change in the rice-cropping system would be useful to consider the practical and cost-effective utilization of remaining land and water resources. Moreover, the trend analysis of NDVI time-series showed negative trends in coastal areas. This indicates that the rice production in coastal areas has been constrained by the saline intrusion. The salt-affected areas are expected to expand under future climate change scenarios. Government support is highly required for sustainable rice production in the Delta.

     

新疆生产建设兵团第四师71团玉米密植高产全程机械化生产技术模式发展调研

从种植品种、种植密度与种植方式、机械化作业和收储烘干等环节对新疆生产建设兵团第四师71团场玉米生产技术的发展进行调研。分析表明,71团场位于西北灌溉玉米区,通过规模化、标准化生产和统一作业管理,以密植增产为基础、子粒收获为核心、绿色防控与秸秆还田为保障构建的玉米密植高产全程机械化绿色生产技术,实现了高产和高效的协同提高与绿色可持续生产。经农业农村部专家指导组田间测产验收,2012年、2014年和2017年连续创造16701 kg/hm^2、18414 kg/hm^2和18447 kg/hm^2的全国玉米大面积(700 hm^2)高产纪录,净利润在15000元/hm^2以上,为现代玉米生产树立了成功的模式和样板。     

Irrigation,nitrogen and gypsum effects on specific gravity and internal defects of Atlantic potatoes

Irrigation, nitrogen and gypsum were investigated in a 3-year study to determine their influence on specific gravity and internal physiological defects. Excess irrigation during August and September reduced specific gravity, increased the incidence of hollow heart, and in some years, internal brown spot. Tuber yields were not significantly affected by excess irrigation. Exclusion of late season irrigation, however, significantly reduced tuber yields. No consistent yield response to nitrogen was evident, but a response up to 168 kg/ha was observed in 1987. Nitrogen rate did not effect hollow heart, internal brown spot or chip color. The incidence of internal brown spot in the tubers of check treatments was quite variable from year to year, and ranged from 8 to 21%. The lowest incidence of internal brown spot observed in 1989 coincided with the highest calcium levels in the tuber peel. Although gypsum treated potatoes had reduced incidence of internal brown spot, the effects were partial and inconsistent. Significant increases in peel and petiole calcium concentrations in the gypsum treated plots only occurred in one year. The peel calcium levels appeared to be influenced more by the season and to a lesser extent by gypsum. Gypsum applications produced no effects on total or US#1 tuber yield, specific gravity, hollow heart, or chip color. Preliminary data also suggested that gypsum did not markedly influence the incidence of blackspot. Based on this study, a routine gypsum application to improve the tuber quality of the variety Atlantic is not recommended.     

Identification of cassava (Manihot esculenta Crantz) genotypes with early storage root bulking

Early bulking (EB) cassava varieties shorten the growth period from planting to harvesting. Cassava is preferred by farmers to many other crops because of its high-yielding potential and ability to survive a 4- to 6-month dry season. However, the crop in some cases is only able to remain alive during the dry season without further starch accumulation. This and some other factors, such as pest destruction during dry season and inability to use the same land for cultivation of other crops such as vegetables, therefore necessitate the development of EB cassava genotypes. The objective of this study was therefore to identify EB cassava genotypes using the difference in fresh storage root yield (FSRY) at different plant ages. Thirty-four cassava genotypes were evaluated at Umudike and Otobi in Nigeria in two seasons at two plant ages of 7 and 12 months after planting (MAP) for FSRY. The data generated were used to classify the cassava genotypes as EB or late bulking (LB). Cassava genotypes with less than 100% increase in FSRY at 12 MAP over the yield at 7 MAP were regarded as EB, whereas those with more than 100% increase were regarded as LB genotypes. This basis was used considering the fact that root thickening in cassava commences at about 2 MAP; hence, the root yield at 7 and 12 MAP represents accumulation of assimilates for 5 and 10 months, respectively. About 65%, 62%, and 79% of the genotypes were classified as EB genotypes at Otobi, Umudike, and across the two locations, respectively.     

施用石灰对红壤旱地土壤酸度和油菜产量的影响

在施石灰石粉的长期定位试验中，种植了５季油菜．结果表明：（１）施用石灰使土壤ｐＨ升高和交换性铝含量下降，其降酸作用与石灰施用量呈正相关．亩施２５０、５００、７５０及１０００ｋｇ石灰石粉的降酸作用分别可维持２、６、７及１０年．（２）施用石灰显著增加了每株荚数而提高油菜籽产量，增产幅度为１９．７％－２．９．６％．过量施用石灰并未引起油菜产量的降低．（３）施用石灰能显著抑制菌核病（连作二年）和田间杂草。（４）施用石灰使土壤ｐＨ＞５．８，交换性铝含量＜０．７ｍｅ／１００ｇ，油菜可获得较高产量。     

隔沟交替灌溉对我国半干旱地区马铃薯水分利用的影响

隔沟交替灌溉（Partialroot-zonedrying,PRD）被认为是一种节水灌溉的方法,它可以提高多种作物的水分利用率。本研究开展于我国甘肃与内蒙两个半干旱马铃薯种植区,比较常规灌溉与隔沟交替灌溉对马铃薯产量和水分利用率的影响。结果表明,由于两个试验点的气候条件与土壤条件不同,所以马铃薯产量存在显著的差异。但是在两试验点中,PRD。处理（隔沟交替灌溉,灌水量为经验灌水量的1／2）的产量与常规灌溉处理（c100,经验灌水量）的产量没有显著的差别,水分利用率却显著提高。研究显示,运用合理的灌溉方式,可以在保证产量不变的基础上节省用水量。另外,在易发生干旱的地区,选用适合的品种,同时采用覆膜技术对于增加马铃薯产量有着重要的作用。     

Effects of long-term use of sodic water irrigation, amendments and crop residues on soil properties and crop yields in rice-wheat cropping system in a calcareous soil

One of the options to ameliorate the deleterious effects of sodic water irrigation is to apply gypsum to soil. We examined whether the application of organic manures or crop residue can reduce the need for gypsum in calcareous soils. A long-term field experiment with annual rice-wheat cropping rotation was conducted for 15 years (1991-2006) on a non-saline calcareous sandy loam soil (Typic Ustochrept) in northwestern, India. The irrigation water treatments included good quality canal water (CW) and sodic water (SW) with residual sodium carbonate (RSC) of 10 mmol_c L⁻¹ from 1991 to 1999 and of 12.5 mmol_c L⁻¹ from 2000 onwards. Gypsum was applied at 0, 12.5, 25, and 50% of the gypsum requirement (GR), to neutralize RSC of the SW. Three organic material treatments consisted of application of farmyard manure (FYM) at 20 Mg ha⁻¹, Sesbania green manure (GM) at 20 Mg ha⁻¹, and wheat straw (WS) at 6 Mg ha⁻¹. The organic materials were applied every year to the rice crop. Continuous irrigation with sodic water for 15 years without gypsum or organic materials resulted in a gradual increase in soil pH and exchangeable sodium percentage (ESP), deterioration of soil physical properties, and decrease in yields of both rice and wheat. The cumulative yield loss in SW irrigated plots without gypsum and organic materials remained <1.5 Mg ha⁻¹ for up to eight years in the case of rice and up to nine years in the case of wheat. Thereafter, marked increase in pH and ESP resulted in further depression in yields of rice by 1.6 Mg ha⁻¹ year⁻¹ and wheat by 1.2 Mg ha⁻¹ year⁻¹. Application of gypsum improved physical and chemical properties of the soil. The beneficial effects on crop yields were visible up to 12.5% GR in rice and up to 50% GR in wheat in most of the years. All the organic materials proved effective in mobilizing Ca²⁺ from inherent and precipitated CaCO₃ resulting in decline in soil pH and ESP, increase in infiltration rate, and a increase in the yields of rice and wheat crops. Although the application of organic materials resulted in comparable reductions in pH and ESP, the increase in yield with SW was higher for both crops with FYM. Pooled over the last six years (2000-2006), application of FYM resulted in 38 and 26% increase in rice and wheat yields, respectively, over SW treatment; corresponding increases in 50% GR treatment (recommended level) was 18 and 19%. During these years, application of GM and WS increased wheat yields by 20%; for rice, GM resulted in 22% increase compared to 17% in WS amended SW irrigated plots. Combined application of gypsum and organic materials did not increase the yields further particularly in the case of FYM and GM treated plots. This long-term study proves that organic materials alone can be used to solubilize Ca from inherent and precipitated CaCO₃ in calcareous soils for achieving sustainable yields in sodic water irrigated rice-wheat grown in annual rotation. The results can help reduce the dependency on gypsum in sodic water irrigated calcareous soils.     

遮雨棚模拟黄土旱塬区降水变化对冬小麦生长及产量的影响

为了解降水变化对黄土旱塬区冬小麦生长及产量的影响,通过遮雨棚模拟冬小麦生长季减少30%降水(R-30%)、正常降水(CK)和增加30%降水(R+30%)情景,于2016-2018年研究了黄土旱塬区两季冬小麦土壤相对有效含水量、LAI、NDVI、生物量、产量及其构成的动态变化特征。结果表明,在降水正常的2016-2017年(降水距平百分率位于±15%以内),与CK相比,R-30%处理的土壤相对有效含水量在返青至抽穗期显著下降,冬小麦冠层NDVI显著降低,LAI和干物质增长速率明显变缓,冬小麦的穗数和千粒重显著降低,而R+30%处理下冬小麦LAI和干物质保持稳定增长优势。R+30%、CK和R-30%三种降水条件下冬小麦产量分别为4.66、3.12和2.43 t·hm~(-2),处理间差异显著。在降水偏多的2017-2018年(降水距平百分率超过30%),不同降水处理间土壤相对有效含水量、冬小麦LAI、冠层NDVI、生物量、产量及其构成等指标均未表现出显著差异。R+30%、CK和R-30%三个处理下冬小麦的产量分别为3.70、3.39和3.14t·hm~(-2),处理间差异亦不显著。因此,在正常降水年份,生长季增加30%降水可使冬小麦显著增产44.2%,减少30%降水可使冬小麦显著减产28.4%;在降水偏多年份,生长季降水增加30%或减少30%对冬小麦的生长及产量没有显著影响。     

异噁唑草酮·噻酮磺隆在玉米不同种植区应用的除草效果和安全性研究

2016～2017年在东北春玉米种植区和黄淮海夏玉米种植区设立田间试验基地,研究除草剂异噁唑草酮·噻酮磺隆悬浮剂在不同区域玉米田播后苗前处理的杀草谱及除草效果、对玉米安全性及对下茬作物生长的影响。结果表明,26.7%异噁唑草酮·噻酮磺隆悬浮剂141.75～283.5 g ai/hm2在玉米播后苗前使用,对东北春玉米种植区主要杂草稗草、狗尾草、藜、反枝苋、苘麻、刺儿菜和黄淮海玉米种植区主要杂草马唐、牛筋草、反枝苋、马齿苋、铁苋菜等禾本科杂草和阔叶杂草均有理想效果,药后40～45 d,异噁唑草酮·噻酮磺隆上述处理对杂草鲜重防效仍在95%左右,可实现一次施药控制玉米全生长期的杂草,在玉米田具有较好的除草增产作用;对后茬播种的小麦、大豆、花生、油菜、菠菜生长无影响。