Performance and behaviour of Bt cotton hybrids under sub-optimal rainfall situation

Growth behaviour and yield performance of Bt cotton hybrids under sub-optimal rainfall situation is of practical significance, because more than 60% of the cotton area is under rainfed condition in India. A field trial conducted in a sandy clay loam soil during the seasons 2006–2007, 2007–2008, and 2008–2009 to study the growth behaviour and yield performance under scanty rainfall situation revealed that growth in both Bt and non-Bt cotton hybrids significantly differed under these parameters. The crop experienced moisture stress at the early stages of growth and again during boll development phase in 2006–2007 and 2008–2009. However, Bt hybrids (1691 kg ha^?1) produced higher seed cotton yield than non-Bt hybrids (1092 kg ha^?1), while the controlled variety (LRA 5166) performed the average of these two (1399 kg ha^?1). Similar trend was evident in respect of bolls per plant (at 90 DAP) and the final harvested bolls in both Bt and non-Bt cotton. Because of Bt gene, the early formed bolls were protected from the boll worms which led to less damage and higher yield with Bt hybrids. Amongst the hybrids, RCHB 708 Bt (1917 kg ha^?1) performed better over the others.     

Studies on method and rate of fertilizer application in apple under mulch in north-western Himalayas

Different methods of fertilizer application-drip fertigation and conventional fertilizer application under drip, surface irrigation, and rainfed conditions were evaluated during 2009–2012 at Krishi Vigyan Kendra, Shimla, India. The experiment was arranged in randomized block design (RBD), replicated thrice. Results suggest that fertigation significantly increased growth parameters over conventional methods. Fruit yield was significantly higher under fertigation (13.7 t ha^?1) over conventional fertilizer application with drip (11.6 t ha^?1), surface irrigation (10.6 t ha^?1), and under rainfed (8.6 t ha^?1). Fruit quality parameters were also superior under fertigation. Fertigation maintained higher available nitrogen (N) and potassium (K) content in 0-30 cm soil layers. Available phosphorus (P) was higher in 0-20 cm soil depths in all the treatments. Fertigation with 80 and 100 percent recommended NPK dose registered statistically comparable results. In addition to higher productivity, fertigation resulted in 20 percent fertilizer savings over drip irrigation and 20 percent fertilizer besides 40 percent water savings over surface irrigation.     

Phosphorus relationships in no‐till small grains

Abstract

Phosphorus (P) fertilizer recommendations for no‐till small grain production are poorly defined. These studies were conducted to determine small grain‐P response relative to the Olsen‐P soil test and compare P‐fertilizer placements with the seed and banded below and to the side of the seed under no‐till field conditions. Phosphorus rates of 0 to 26 kg P/ha were evaluated on seven spring barley (Hordeum vulgare L.), 11 spring wheat, and six winter wheat (Triticum aestivum L.) locations in central and northcentral Montana between 1986 and 1990. Grain yield, grain protein, test weight, above‐ground crop yield, plant P concentration at maturity, and P uptake were measured. One winter wheat location had a significant yield response to P; all other locations had non‐significant yield responses. Grain protein, test weight, P concentration, and P uptake were all unaffected by P rate or P placement. Both the ANOVA and paired t‐test were used to analyze the P‐placement data and were all nonsignificant. Slopes of grain yield response (grain yield for each P rate minus the grain yield without P), P concentration, and P uptake versus P rate were analyzed with the t‐test; none of the P‐response slopes were greater than zero. The P responses by individual crop were regressed against P rate, Olsen‐P soil test, available soil water at planting, and pH. Phosphorus rate was not a significant factor in any of the equations. Significant and useful predictive equations for grain yield response could not be generated; however, equations predicting P concentration and P uptake were developed. The Cate‐Nelson graphical analysis was unsuccessful in estimating an Olsen‐P soil test critical level. All attempts failed to relate grain yield or grain yield response to the Olsen‐P soil test and/or P rate. When P soil tests are higher than 12 mg/kg, no‐till grain growers should consider applying a maintenance level of P fertilizer, about 5 to 10 kg P/ha either banded below or with the seed, to maintain soil P levels.     

Application of Mitscherlich–Bray Equation for Fertilizer Use on Groundnut

Field experiments were conducted at two locations in order to formulate phosphorus and potassium fertilizer recommendations of groundnut (Arachis hypogea) based on Mitscherlich–Bray equation. The treatments comprised four levels of phosphorus (0, 30, 60, and 90 kg phosphorus pentoxide (P₂O₅) ha^?1) and three levels of potassium (0, 30, and 60 kg potassium oxide (K₂O) ha^?1) in all possible combinations. Theoretical maximum yield of groundnut was calculated by plotting log y (pod yield) versus 1/x (amount of nutrients applied). Fertilizer recommendation for various soil fertility levels and yield target were developed, and their validities were tested by conducting two field verification trials on the same soil. The results showed that although general recommended fertilizer dose resulted in highest yield of groundnut at both the locations, but value cost ratio and rate of increase in income were lowest with this fertilizer treatment, and 90% of maximum yield treatment was superior in terms of economics of fertilizer and risk factor.     

膜下滴灌棉花氮磷肥料施用效果研究

氮肥随水施用可显著提高棉花单株铃数、单铃重和籽棉产量,促进棉花对氮、磷素的吸收,尤其在壤土棉田的效果较明显。随水施用磷肥对棉花单株铃数影响不大,籽棉产量较不施磷肥处理提高8.80～17.40%,其在壤土棉田上的增产效果优于粘土棉田。磷肥随水滴施可提高氮、磷肥料利用率,与基施相比氮肥利用率提高4.85～12.34%,磷肥利用率提高36.75～45.88%,且在壤土棉田上的施用效果优于粘土棉田。     

Impacts of Bt transgenic cotton on integrated pest management

Transgenic cotton that produced one or more insecticidal proteins of Bacillus thuringiensis (Bt) was planted on over 15 million hectares in 11 countries in 2009 and has contributed to a reduction of over 140 million kilograms of insecticide active ingredient between 1996 and 2008. As a highly selective form of host plant resistance, Bt cotton effectively controls a number of key lepidopteran pests and has become a cornerstone in overall integrated pest management (IPM). Bt cotton has led to large reductions in the abundance of targeted pests and benefited non-Bt cotton adopters and even producers of other crops affected by polyphagous target pests. Reductions in insecticide use have enhanced biological control, which has contributed to significant suppression of other key and sporadic pests in cotton. Although reductions in insecticide use in some regions have elevated the importance of several pest groups, most of these emerging problems can be effectively solved through an IPM approach.     

国际转基因作物的安全性争论——几个事件的剖析

摘要：国际转基因作物安全性争论的实质并不纯粹是科学问题,而是经济和贸易问题。对安全性争论的几个典型事件从科学角度作了分析。     

Sweet Potato Response to Boron Application on an Alfisols in the Subhumid Tropical Climate of India

Abstract

Splitting of sweet potato tubers because of boron (B) deficiency is a major cause of reduction in marketable tuber yield in India. Soil and plant tests are employed in this study to determine the fertilizer B requirement (FBR). Fertilizer B requirement of sweet potatos grown on an Alfisols under rainfed conditions was evaluated by two simple methods. In the first method, the relationship between B uptake and sweet potato tuber yield was utilized to find the B uptake at a given sweet potato tuber yield. This relationship was then used to find the amount of B applied for that particular uptake to set the targeted yield. In the second method, FBR was determined using the equation: FBR=(U_B?U₀)/BRF, where U_B is B uptake at a given yield, U₀ is B uptake from unfertilized soil, and BRF is the recovery of applied B. All of these parameters were determined in a field experiment with sweet potatos grown on Alfisols under rainfed conditions. The results of the study indicated a very good relation between observed value of FBR and predicted values determined by both the methodologies. Results of the study suggest that the simple models developed based on B uptake can be utilized for determining the B requirements of sweet potato.     

棉花高产和磷高效的磷肥基施追施配合技术研究

【目的】 本文比较了不同磷肥基施、追施比例对棉花生物量、产量及养分吸收的影响，以优化新疆膜下滴灌棉花的磷肥施用技术。 【方法】 2009—2011年连续三年进行了田间试验。试验共设3个处理:不施磷肥，磷肥全部基施，磷肥滴灌追施 (2009、2010年为磷肥50%基施和50%滴灌追施，2011年为磷肥65%基施和35%滴灌追施)，追施的磷肥分2次在棉花蕾期和初花期随水施入。各处理的氮、钾肥用量相同，氮肥全部滴灌追施，钾肥全部基施。棉花成熟期测定了棉株生物量、籽棉产量和磷肥的利用率。 【结果】 施用磷肥显著提高了棉花地上部生物量，与不施磷肥相比，磷肥基施显著增加了棉花的叶、茎、籽和纤维的生物量，分别增加15%、9%、9%和11%，磷肥滴灌追施显著增加了叶、茎、壳、籽和纤维的生物量，分别增加21%、23%、21%、12%和13%。施用磷肥能够显著提高棉花产量，与不施磷肥相比，磷肥全部基施籽棉平均增产8%，磷肥滴灌追施籽棉平均增产13%，而磷肥滴灌追施的产量比磷肥全部基施提高5%。施用磷肥显著增加了棉花的磷素吸收量，磷肥全部基施的磷肥平均利用率为18%，而磷肥滴灌追施的磷肥平均利用率为23%。磷肥35%滴灌追施的增产率和磷肥利用率分别为18%和24%，50%滴灌追施处理两者分别为11%和22%。 【结论】 与不施磷肥相比，磷肥全部基施与部分磷肥滴灌追施都能显著提高棉花生物量和产量，增加磷素吸收量，而磷肥部分滴灌追施的效果优于磷肥全部基施，磷肥65%基施和35%滴灌追施的增产效果好于50%基施和50%滴灌追施。      

我国Bt棉花商业化的环境影响与风险管理策略

Bt转基因棉花于1997年在我国商业化种植，到2006年种植面积已达棉花总面积的70％。环境影响监测表明，Bt棉花有效地控制了棉铃虫和红铃虫的发生和为害，但盲蝽蟓类害虫演化上升成为棉田的主要害虫。抗性分析显示，虽然棉铃虫自然种群对Bt棉花抗性基因频率没有明显的变化，但Bt棉花髙强度种植地区的棉铃虫耐受性正逐年提高，已成为影响Bt棉花持续利用的主要因素。基于Bt棉花环境风险和影响因子的综合分析，本文讨论了Bt棉花环境风险的管理策略。     

漫灌和滴灌棉花土壤有效磷丰缺指标与临界值研究

【目的】 土壤有效磷含量是棉花施用磷肥的重要依据,由于连续多年施用磷肥,新疆棉花土壤有效磷含量有较大幅度的增加,但对棉花土壤有效磷的评价仍然使用以前的标准,磷肥推荐用量不能适应棉花生产。因此,明确土壤有效磷的临界值,能为有效指导棉花合理施用磷肥提供理论依据。 【方法】 选择新疆281个试验点,建立缺磷区相对产量与土壤有效磷含量之间的关系,进行对数方程模拟,分别将相对产量带入相应的对数方程,求出对应的土壤有效磷分级指标值,同时采用线性 + 平台模型拟合求出土壤有效磷临界值,根据有效磷分级推荐施用磷肥。 【结果】 对棉花产量和土壤有效磷的相关性进行直线、指数和对数模拟,3种回归方程的相关系数都达到了1%显著水平,其决定系数R2分别为0.500、0.470和0.590,以对数回归方程相关性最高。采用线性 + 平台模型拟合棉花相对籽棉产量和土壤有效磷的关系,棉花相对籽棉产量对土壤有效磷含量的反应分成2段,拐点即为土壤有效磷临界值,此时棉花土壤有效磷的临界值为22.0 mg/kg。当土壤有效磷 ≥ 22.0 mg/kg时,y = 93.77,表明随土壤有效磷的增加,棉花相对籽棉产量不变,此时施用磷肥几乎没有增产作用;当土壤有效磷 < 22.0 mg/kg时, y = 62.86 + 1.405x,施磷肥可以促进棉花增产 (R2 = 0.63**)。棉花的磷肥利用率随土壤有效磷含量的增加而大幅度降低。当土壤有效磷 < 5 mg/kg时,漫灌条件下磷肥的利用率为25.7%,滴灌为21.6%,二者差异不显著;当土壤有效磷5～12 mg/kg时,漫灌和滴灌条件下磷肥的利用率也没有显著差异;当土壤有效磷12～25 mg/kg时,滴灌条件下磷肥的利用率为15.0%,比漫灌显著增加4.6个百分点;当土壤有效磷为25～38 mg/kg和> 38 mg/kg时,漫灌和滴灌条件下磷肥的利用率差异又变得不显著。不论漫灌和滴灌,棉花磷肥的平均利用率约为15.9%。 【结论】 根据棉花相对产量的 < 70%、70%～80%、80%～90%、90%～95%、> 95%,将土壤有效磷划分为5个等级,即 < 5 mg/kg、5～12 mg/kg、12～25 mg/kg、25～38 mg/kg和 > 38 mg/kg,土壤有效磷临界值为22.0 mg/kg。漫灌条件下磷肥的平均利用率为15.2%,而滴灌条件下磷肥的平均利用率为17.1%,差异不显著。棉花土壤有效磷丰缺指标为极低、低、中、高、极高,获得了土壤有效磷临界值及不同棉花产量下的推荐施磷量。      

农田秸秆覆盖条件下冬小麦增产的水氮条件

通过田间试验建立了冬小麦产量与灌水量及施氮量的关系模型,并作了模拟分析,以期研究旱地农田秸秆覆盖条件下冬小麦增产的水氮条件.结果表明:秸秆覆盖的冬小麦能否增产与水肥供应关系密切.生育期间没有补充灌水时,覆盖增产主要取决于氮肥用量,氮肥投入较少时覆盖冬小麦经济产量能取得显著的增产效果;氮肥用量较高时产量低于未覆盖处理.因此,在雨养农业区,通过配合适量的氮肥完全能够做到秸秆覆盖下增产增收.在不同氮肥用量前提下,覆盖的增产效果除了与生育期总灌水量有关外,还与灌水量在各生育期间的分配有关.因此,在有灌溉条件的地区,根据氮肥投入情况,将有限的水分配在作物最需要的时期才能取得秸秆覆盖下的节水高产.     

应用~(15)N研究氮肥运筹对棉花氮素吸收利用及产量的影响

【目的】有关棉花适宜的施氮时期存在争议,国外有学者推荐最佳施氮时期为出苗后和现蕾期,也有研究认为播前和初花期各施一半较好。氮同位素示踪技术能区分作物吸收利用的肥料氮及土壤氮,并能深入细致研究施入氮肥的去向及在作物体内的分配。本文采用氮同位素示踪技术研究氮肥底追比例,施氮时期对棉花氮素吸收和产量的影响,以期为华北平原棉区氮肥管理提供理论依据。【方法】采用盆栽试验,以转Bt+Cp TI基因抗虫棉品种中棉所79(CCRI 79)、中棉所60(CCRI 60)为材料,设氮肥底施与初花期追施比例1∶1(N1)、1∶2(N2)、0∶1(N3)、氮肥底施与蕾期追施比例0∶1(N4)4个处理,研究氮肥运筹对棉花初花期、收获期15N吸收、15N回收率、生物量积累和籽棉产量的影响。【结果】初花期棉株不同器官的氮素吸收来自氮肥(Ndff)的比例随底肥氮施用量的增加而显著增加,增幅为25.88%42.45%。收获期不同处理棉花单株Ndff%随追施氮量的增加而显著增加,增幅为26.92%54.14%,N3、N4处理的棉花单株Ndff%显著高于N1和N2。N2处理的棉花单株籽棉产量高于其他处理,但与N1处理的差异不显著,N2处理单株生物量与N1、N3差异不显著。2个品种N3、N4处理的棉花收获期单株15N积累量均显著高于N1和N2处理,棉株收获期15N回收率均显著高于N1。N2处理的棉花收获期15N回收率高于N1处理,但差异未达到显著水平。棉花收获后N2处理土壤15N回收率低于N1,但差异不显著。【结论】本试验条件下,2个棉花品种氮素底追比为1∶2时的籽棉产量与15N回收率优于底追比为1∶1处理,底追比为0∶1的处理15N回收率在4个处理中最高,但未显示出产量优势,这些结果有待在大田试验中进一步验证。     

Spatial interpolation of soil hydraulic properties and simulated rice yield

Abstract. Simulated estimates of crop yield were made for rainfed rice in a 50 ha dryland rice area. The aim was to investigate how soil units and management units of different sizes with different yields could be used to obtain values for areas of land. Two procedures were applied. First, yields were simulated at six sites, that were representative of six soil mapping units. Second, yields were simulated using soil information from 133 auger sites, and were interpolated over management units using block kriging. Differences between the two procedures for the total area and for a test set of 22 additionally sampled locations were small. A 60% increase in precision was achieved when relatively large management units were defined.
A Geographical Information System was used to identify areas with greatest yield potential for rainfed dryland rice. Statistical analysis showed that the six soil units could be grouped into three yield classes. The largest yields were obtained for a sub-area comprising 11% of the survey area which was associated with a slowly permeable Bg horizon in the soil profile.
It was concluded that the best procedure for the spatial interpolation of simulated rice yield should be based on preliminary simulation of crop yields. A sensitivity analysis of the impact of weather variability and soil heterogeneity on the variation of yield was useful to detect the importance of their contributions. The procedures developed in this study are of value in obtaining a reliable estimate of average yield, and can consequently be used for associated cost-benefit calculations.     

小田块变量施肥系统优化设计与应用

针对苏南地区推广变量施肥存在的施肥策略过于精细化导致高密度土壤信息不易获取和普通的施肥机械难以达到播量精度等主要技术障碍,该文建立了一种简单实用的变量施肥方案,在现有机械式播种施肥机基础上进行了自动化改造,构建了一套基于简易电子处方图系统的变量施肥系统;变量施肥作业时,以单个自然田块为处理单元,依托所建立的简单实用的电子处方图系统,实现多种肥料按需配比、同一田块均匀施肥、不同田块变量施肥的功能。为提高播量精度和播量稳定性,对普通精度GPS模块的数据进行了差分和卡尔曼滤波处理,对外槽轮施肥播种器结构进行了优化设计。田间试验结果表明:电子处方图运行结果准确,施肥播种机工作稳定,种子和肥料的最大和平均播量误差分别为3.91%和2.09%,最大和平均动态误差分别为4.52%和1.48%。该研究可为苏南小田块地区推广变量施肥提供技术参考。     

施氮量对棉花功能叶片生理特性、氮素利用效率及产量的影响

【目的】黄河流域棉区是我国三大棉区之一,氮肥管理在棉花生产中至关重要,氮肥供应不足或过量会影响棉花的皮棉产量和纤维品质,过量施氮可能导致棉花营养生长过旺,产量下降,也会造成不必要的浪费及棉田环境污染,氮肥供应不足会导致棉花生物量较小,皮棉产量降低,纤维品质下降。本文通过3年不同氮肥用量的田间小区定位试验,研究施氮量对棉花功能叶生理特性、氮素利用效率及籽棉产量的影响,旨在探讨黄河流域棉区华北平原亚区中等肥力棉田适宜施氮量,揭示棉花氮素高效利用的相关机理。【方法】田间试验于2011 2013年在河南安阳县中棉所试验农场进行,供试田块为多年连作棉田,土壤为壤质潮土,2011年播种前0—20 cm土层土壤有机质、全氮、速效氮(N)、速效磷(P)、速效钾(K)含量分别为11.24 g/kg、0.82 g/kg、77.43 mg/kg、16.69 mg/kg、129.82 mg/kg。以转Bt+Cp TI中熟棉花品种中棉所79为材料,采用随机区组设计,重复4次,设置0、90、180、270、360、450 kg/hm26个施氮水平,氮肥底施和初花期追施各半,磷(P2O5)、钾(K2O)全部底施,施用量均为120kg/hm2。试验小区长10 m,宽4.8米,每小区6行棉花,种植密度57500 plant/hm2。2011年4月17日播种,2012年4月25日播种,2013年5月3日播种。2013年研究了施氮量对初花期棉花功能叶光合速率、不同生育期棉花群体叶面积指数(LAI)、不同生育期棉花功能叶叶绿素含量、丙二醛(MDA)含量、谷氨酰胺合成酶(GS)活性的影响,2012、2013年研究了施氮量对棉花氮素内在利用率、氮肥农学利用率、氮素生理利用率、氮肥回收率及籽棉产量的影响。【结果】随施氮量的增加,不同生育期棉花群体LAI、功能叶叶绿素含量、GS活性、初花期棉花功能叶净光合速率呈增加的趋势,而功能叶MDA含量呈下降趋势。施氮量270、360 kg/hm2处理棉花在盛铃期群体LAI较适宜,吐絮期棉花功能叶能维持较高的生理活性,可为棉花高产提供物质保障。棉花氮素积累量、籽棉产量与施氮量间均呈二次曲线关系,棉花氮肥农学利用率和氮素内在利用率随施氮量增加显著下降,施氮量超过180 kg/hm2时氮素生理利用率下降,施氮量为270 kg/hm2时氮肥回收率高于其他处理。施氮量360 kg/hm2时,籽棉平均产量最高,显著高于施氮量为0、90 kg/hm2的处理,但与施氮量180、270、450 kg/hm2处理间差异不显著。棉花3年籽棉平均产量(Y)与施氮量(N)的效应方程为Y=3143.8036+4.2057N-0.006220N2(R2=0.9805,P=0.002717);棉花的最高产量施氮量为338.1 kg/hm2,经济最佳施氮量为299.7 kg/hm2。【结论】黄河流域棉区华北平原亚区中等肥力棉田施氮量超过270 kg/hm2时,棉花氮肥农学利用率、氮素内在利用率、氮素生理利用率、氮肥回收率开始下降,该区棉田推荐经济施氮量299.7 kg/hm2。     

Assessing the fertilizer phosphorus requirement of grain sorghum

Abstract

Assessing the fertilizer phosphorus (P) requirements (FPR) of crops is an important component of research for efficient and rational use of fertilizers. Soil and plant tests are employed to determine the FPR. Two methods were evaluated for determining the FPR of sorghum grown on a Vertisol under rainfed conditions. The first method was based on P on applied P uptake, and grain yield relationships for grain sorghum. In this method, P uptake at a given yield was determined from the relationship between total P uptake and grain yield. The amount of fertilizer P applied for the given P uptake and grain yield was then, determined from the relationship between P applied and P uptake. In the second method, FPR was determined using the equation: FPR=(Up‐U0)/PRF, where Up is P uptake at a given yield, U0 is P uptake from unfertilized soil, and PRF is the recovery of applied P. The parameters, U0, Up, and PRF were determined in a field experiment with sorghum grown on a Vertisol under rainfed conditions. There was a good agreement between the observed value of FPR and predicted values determined by the two methods. These results suggest that the simple models based on P uptake can be utilized for determining the fertilizer requirements of crops.     

Fate of Bt Protein and Influence of Corn Hybrid on Ethanol Production

Corn hybrids were compared to determine the fate of recombinant Bt protein (CRY1Ab from Bacillus thuringiensis) in coproducts from dry grind and wet‐milled corn during production of fuel ethanol. Two pairs of Bt and non‐Bt hybrids were wet milled, and each fraction was examined for the presence of the Bt protein. Bt protein was found in the germ, gluten, and fiber fractions of Bt hybrids. In addition, one set of Bt and non‐Bt hybrids were treated by the dry‐grind ethanol process and Bt protein was monitored during each step of the process. The Bt protein was not detected after liquefaction. Subsequent experiments determined that the Bt protein is rapidly denatured at liquefaction temperatures. Finally, five hybrids were compared for ethanol yield after dry grinding. Analysis of fermentation data with an F‐test revealed the percent of total starch available for conversion into ethanol varied significantly among the hybrids (P < 0.002), indicating ethanol yield is not exclusively dependent on starch content. No difference, however, was observed between Bt and non‐Bt corn hybrids for either ethanol productivity or yield.     

种植密度氮肥互作对棉花产量及氮素利用效率的影响

种植密度和氮肥投入是棉花生产中重要的管理措施,为提高棉花产量与氮素利用效率,于2013-2014年以转Bt+Cp TI品种中棉所79为材料,在河南省安阳市中棉所试验农场设置了3个种植密度(分别为3.00,5.25,7.50株/m~2),4个氮肥用量(分别为0,112.5、225.0、337.5 kg/hm~2,以N计),探讨种植密度与氮肥对棉花产量及氮素利用效率的影响,结果表明:棉花的叶面积指数、生物量与氮吸收量随种植密度和氮肥用量的增加而增加,而收获指数随种植密度和氮肥用量的增加而下降,中密中氮处理(种植密度5.25株/m~2、施氮量225.0 kg/hm~2)单位面积成铃数较多,籽棉和皮棉产量、氮肥回收利用率优于其他处理,高密低氮处理(种植密度7.50株/m~2、施氮量112.5 kg/hm~2)氮肥农学利用效率、氮肥偏生产力、氮生理利用率高于其他处理,而籽棉、皮棉产量与中密中氮处理较接近,研究表明增密减氮可实现棉花的高产高效。