Combining ability of Egyptian cotton(Gossypium barbadense L.)reveals genetic potential for improved yield and fiber quality

Background As the most widely cultivated fiber crop,cotton production depends on hybridization to unlock the yield potential of current varieties.A deep understanding of genetic dissection is crucial for the cultivation of enhanced hybrid plants with desired traits,such as high yield and fine fiber quality.In this study,the general combining ability(GCA)and specific combining ability(SCA)of yield and fiber quality of nine cotton parents(six lines and three testers)and eighteen F1 crosses produced using a line×tester mating design were analyzed.Results The results revealed significant effects of genotypes,parents,crosses,and interactions between parents and crosses for most of the studied traits.Moreover,the effects of both additive and non-additive gene actions played a notably significant role in the inheritance of most of the yield and fiber quality attributes.The F1 hybrids of(Giza 90×Aust)×Giza 86,Uzbekistan 1×Giza 97,and Giza 96×Giza 97 demonstrated superior performance due to their favorable integration of high yield attributes and premium fiber quality characteristics.Path analysis revealed that lint yield has the highest positive direct effect on seed cotton yield,while lint percentage showed the highest negative direct effect on seed cotton yield.Principal component analysis identified specific parents and hybrids associated with higher cotton yield,fiber quality,and other agronomic traits.Conclusion This study provides insights into identifying potential single-and three-way cross hybrids with superior cotton yield and fiber quality characteristics,laying a foundation for future research on improving fiber quality in cotton.

Growth, yield and fiber quality characteristics of Bt and non-Bt cotton cultivars in response to boron nutrition

Background Boron(B)deficiency is an important factor for poor seed cotton yield and fiber quality.However,it is often missing in the plant nutrition program,particularly in developing countries.The current study investigated B’s effect on growth,yield,and fiber quality of Bt(CIM-663)and non-Bt(Cyto-124)cotton cultivars.The experimental plan consisted of twelve treatments:Control(CK);B at 1 mg·kg^(−1) soil application(SB1);2 mg·kg^(−1) B(SB2);3 mg·kg^(−1) B(SB3);0.2%B foliar spray(FB1);0.4%B foliar spray(FB2);1 mg·kg^(−1) B+0.2%B foliar spray(SB1+FB1);1 mg·kg^(−1) B+0.4%B foliar spray(SB1+FB2);2 mg·kg^(−1) B+0.2%B foliar spray(SB2+FB1);2 mg·kg^(−1) B+0.4%B foliar spray(SB2+FB2);3 mg·kg^(−1) B+0.2%B foliar spray(SB3+FB1);3 mg·kg^(−1) B+0.4%B foliar spray(SB3+FB2).Each treat-ment has three replications,one pot having two plants per replication.Results B nutrition at all levels and methods of application significantly(P≤0.05)affected the growth,physiological,yield,and fiber quality characteristics of both cotton cultivars.However,SB2 either alone or in combination with foliar spray showed superiority over others,particularly in the non-Bt cultivar which responded better to B nutrition.Maxi-mum improvement in monopodial branches(345%),sympodial branches(143%),chlorophyll-a(177%),chlorophyll-b(194%),photosynthesis(169%),and ginning out turn(579%)in the non-Bt cultivar was found with SB2 compared with CK.In Bt cultivar,although no consistent trend was found but integrated use of SB3 with foliar spray performed relatively better for improving cotton growth compared with other treatments.Fiber quality characteristics in both cultivars were improved markedly but variably with different B treatments.Conclusion B nutrition with SB2 either alone or in combination with foliar spray was found optimum for improving cotton’s growth and yield characteristics.

Evaluation of Weed Control Efficacy and Seed Cotton Yield in Glyphosate Tolerant Transgenic Cotton

Cotton is one of the important crops that have been genetically altered to address challenges with weed and insect control. The research was conducted with glyphosate resistant cotton hybrids during winter irrigated season of 2009-10 and 2010-11 at the experimental site of Tamil Nadu Agricultural University, Coimbatore, with the objective, to find out the weed control efficacy and yield of transgenic cotton hybrid with the application of glyphosate. Glyphosate was applied as post-emergence application on 25 and 65 DAS at 900, 1350, 1800, 2700, 3600 and 5400 g a.e./ha in MRC 7347 BG-II RRF test hybrid. These treatments were compared with hand weeding on 15 and 30 DAS and unweeded control. In both sprays, post-emergence application of glyphosate 2700, 3600 and 5400 g a.e./ha registered lower weed density and higher weed control efficiency in transgenic cotton hybrid compared with other treatments. Seed cotton yield (3195 and 3092 kg·ha-1 during 2009-10 and 2010-11 respectively) was significantly higher in post-emergence application of glyphosate at 2700 g a.e./ha. Increased use of transgenic cotton with herbicide and pest resistance has resulted in more efficient insect and weed management practices.

Effects of plant density and nitrogen rate on cotton yield and nitrogen use in cotton stubble retaining fields

Increasing nitrogen(N)rate could accelerate the decomposition of crop residues,and then improve crop yield by increasing N availability of soil and N uptake of crops.However,it is not clear whether N rate and plant density should be modified after a long period of cotton stubble return with high N rate.This study seeks to assess the effects of N rate and plant density on cotton yield,N use efficiency,leaf senescence,soil inorganic N,and apparent N balance in cotton stubble return fields in Liaocheng,China,in 2016 and 2017.Three plant densities 5.25(D_(5.25)),6.75(D_(6.75))and 8.25(D_(8.25))plants m^(-2) and five N rates 0(N_(0)),105(N_(105)),210(N_(210)),315(N315),and 420(N420)kg ha^(-1) were investigated.Compared to the combination used by local farmers(D_(5.25)N_(315)),a 33.3%N reduction and a 28.6%increase in plant density(D_(6.75)N_(210))can maintain high cotton yield,while a 66.7%N reduction at 6.75 plants m^(-2)(D_(6.75)N_(105))can only achieve high yield in the first year.Biological yield increased with the increase of N rate and plant density,and the highest yield was obtained under 420 kg N ha^(-1) at 8.25 plants m^(-2)(D_(8.25)N_(420))across the two years under investigation.Compared to D5.25N315,N agronomic efficiency(NAE)and N recovery efficiency(NRE)in D_(6.75)N_(210) increased by 30.2 and 54.1%,respectively,and NAE and NRE in D6.75N105 increased by 104.8 and 88.1%,respectively.Soil inorganic N decreased sharply under 105 kg N ha^(-1),but no change was found under 210 kg N ha^(-1) at 6.75 plants m^(-2).N deficit occurred under 105 kg N ha^(-1),but it did not occurr under 210 kg N ha^(-1) at 6.75 plants m^(-2).Net photosynthetic rate and N concentration of leaves under N rate ranging from 210 to 420 kg ha^(-1) were higher than those under N rate of 0 or 105 kg N ha^(-1) at all three densities.The findings suggest that D6.75N210 is a superior combination in cotton stubble retaining fields in the Yellow River Valley and other areas with similar ecologies.

Architecture of stem and branch affects yield formation in short season cotton

The cotton direct seeding after wheat(rape) harvested is under trial and would be the future direction at the Yangtze River Valley region of China.The objective of this study was to quantify the effects of branch and stem architecture on cotton yield and identify the optimal cotton architecture to compensate the yield loss due to the reduction of individual production capacity under high planting density in the direst seeding after wheat harvested cropping system.The characteristics of the stem and branch architecture and the relationships between architecture of the stem and branch with yield formation were studied on eight short season cotton cultivars during 2015 and 2016 cotton growth seasons.Based on the two years results,three cultivars with different architectures of stem and branch were selected to investigate the effect of mepiquat chloride(MC) application on the architecture of the stem and branch,boll retention,and the yield in 2017.Significant differences were observed on plant height,all fruiting nodes to branches ratio(NBR) in the cotton plant,and the curvature of the fruiting branch(CFB) among the studied cultivars.There were three types of stem and fruiting branch structures: Zhong425 with stable and suitable plant height and NBR(about 90 cm and 2.5,respectively),high CFB(more than 10.0),and high boll retention speed and seed cotton yield;Siyang 822 with excessive plant height and NBR,low CFB,and low boll retention speed and seed cotton yield;and other studied cultivars with unstable structure of stem and branch,boll retention speed,and seed cotton yield across years.And MC application could promote the appropriate plant height and NBR and high CFB and thus resulted in high boll retention speed and the yield.The results suggested that the suitable plant height and NBR(about 90 cm and 2.5 respectively),and high CFB(more than 10.0),which was related to both genotype and cultural practice,could promote the higher boll retention speed and seed cotton yield.

Impact of Tillage and Herbicides on Weed Density, Yield and Quality of Cotton in Wheat Based Cropping System

Conservation tillage may improve yield of cotton in addition to improvement in soil quality if practiced for longer period. However, the practice may not be productive in short-term particularly when severe weeds are infesting the crops such as Cynodon dactylon, Conyza canadensis, Tribulus terrestris, and Cyperus rotundus, etc. Recent studies indicate that conventional tillage （CT） is more productive than zero tillage （ZT）/reduced tillage （RT）. Performance of cotton under three tillage systems, viz., ZT, RT and CT; and five herbicides, i.e., haloxyfop-R-methyl 10.8 EC （108 g a.i. ha^-1）, lactofen 24 EC （168 g a.i. ha^-1）, haloxyfop 10.8 EC ＋ lactofen 24 EC, hand weeding, and weedy check were evaluated during 2010-2011 at Gomal University, D.I.Khan, Pakistan, to explore the best management option for effective weed control, enhanced yield and quality of cotton grown after wheat. The results revealed that hand weeding and Haloxyfop as post emergence alone or in combination with Lactofen reduced weed density to the minimum irrespective of the tillage systems. Excessive rainfall and cooler temperature limited cotton growth and yield in 2010. The adverse weather conditions had more adverse effect on boll weight under ZT and RT than CT. Haloxyfop ＋ lactofen produced higher seed cotton yield in RT than ZT, however, it could not exceed CT. Broad-spectrum herbicides x CT produced the highest number of bolls/plant, boll weight and seed cotton yield. Fiber quality and net returns were also the highest in broad-spectrum herbicides x CT. In conclusion, broad-spectrum herbicides under CT were more productive in wheat based cropping system on silty clay soil of D.I.Khan.

Effects of plant density on cotton yield components and quality

Yield and ifber quality of cotton even varies within locules in a bol, but it is not clear how yield components and quality parameters are altered across seed positions of a locule （SPL）. A ifeld experiment was arranged in a split plot design with transgenic insect resistant Bt （Bacilus thuringiensis） cotton hybrid cultivar CRI75 and conventional cultivar SCRC28 as the main plots, and three plant densities （15000, 51000 and 87000 plants ha–1） as the subplots in 2012 and 2013 at Anyang, Henan Province, China. Cotton was hand harvested by node and fruiting position, and then seeds of the ifrst fruiting posi-tion bols from nodes 6–10 were separated by SPL. The effects of plant density on lint yield, ifber quality, especialy across SPL were determined. It was showed that plant densities of 51000 and 87000 plants ha–1 increased lint yield by 61.3 and 65.3% in 2012 and 17.8 and 15.5% in 2013 relative to low plant density （15000 plants ha–1）, however, no signiifcant differ-ence was observed between 51000 and 87000 plants ha–1. The number of bols （bol density） increased while bol weight decreased as plant density raised, and no signiifcant changes occured in lint percentage in 2013 but increased with plant density in 2012. The number of bols in upper nodes and distal fruiting positions, the number of seeds per bol, seed area （SA） and seed vigor index increased with decreasing plant density. Seed area was found to be greater from the base to the middle compared to the apex of a locule. Mote frequency （MF） increased as plant density increased, and ifber quality was the best at the middle of the locule regardless of plant density. As the number of ifbers per seed area is geneticaly determined, adjusting plant density to produce more seeds and greater seed area can be a potentialy promising alternative to improve lint yield in cotton. These ifndings might be of great importantance to cotton breeding and ifled management.

Evaluation of Some Promising Soybean Genotypes to Infestation with Cotton Leafworm (Spodoptera littoralis) under Field Conditions

A two-year study was carried out in Giza Agricultural Experiments and Research Station, Agricultural Research Center (ARC), Giza, Egypt in the 2020 and 2021 summer seasons to evaluate the relative tolerance of ten soybean genotypes for cotton leafworm infestation under field conditions. Soybean genotypes H11L145, H155, H113, H4L4, H15L17, H129, H30, H19L96, Giza 111, and Crawford were distributed in randomized complete blocks design with three replications. Soybean genotypes differed significantly for cotton leafworm at the 6th, 7th, and 8th week from sowing. Low values of cotton leafworm assemblages were recorded for H113, H4L4, H15L17, Giza 111, and H129. Low percentages of the larval survival number and weight, as well as the number of the survival of pupa were recorded by feeding on leaves of genotypes H4F4, H15L17, and Giza 111 under laboratory conditions. There were significant differences among the studied genotypes in most yield attributes in both seasons. Soybean genotypes H15L17, Giza 111, H113, H129, H19L96, and H4L4 gave higher seed yield per ha, meanwhile soybean genotypes H155, H19L96, H30, Giza 111, and H15L17 had higher seed oil content than the other genotypes in both seasons. The number and weight of larvae surviving, as well as the number of pupa survival, were negatively correlated with leaf total phenols and seed oil content. It can be concluded that soybean genotypes H15L17, H4L4, and Giza 111 are promising genotypes with desirable seed oil content for tolerating cotton leafworm infestation in breeding programs.

两种覆盖方式下灌水定额对土壤温度变化、棉花产量及水分利用效率的影响

【目的】探究不同覆盖方式和灌水定额对棉花生产的影响。【方法】于2017―2019年在新疆阿拉尔市开展大田试验,其中,2017―2018年膜下滴灌试验以新陆中46号为供试材料,设置24 mm(M1)、30 mm(M2)和36 mm(M3)3个灌水定额;2018―2019年无膜滴灌试验以中棉619为供试材料,设置36 mm(W1)、45 mm(W2)和54 mm(W3)3个灌水定额;分析不同处理对10 cm、20 cm、40 cm土层土壤温度和土壤含水量、籽棉产量以及灌溉水利用效率的影响。【结果】2种模式下棉田10 cm、20 cm和40 cm土层土壤含水量和籽棉产量均随灌水定额的增大呈增加趋势。M2、M3处理的籽棉产量分别较M1处理显著增加8.82%~11.47%和14.24%~18.96%;W2、W3处理的籽棉产量分别较W1处理显著增加15.18%~22.61%和32.53%~46.29%。土壤温度和灌溉水利用效率均随灌水定额的增大呈降低趋势。M2、M3处理的灌溉水利用效率分别较M1处理显著降低10.82%~12.94%和20.70%~23.84%;W2、W3处理的灌溉水利用效率分别较W1处理降低1.91%~7.85%和2.47%~11.65%。2018年灌水定额相同时,M3处理的土壤含水量、0~40 cm土层土壤温度、籽棉产量和灌溉水利用效率均高于W1处理。基于逼近理想解排序法(technique for order preference by similarity to ideal solution, TOPSIS)的综合评价表明,膜下滴灌处理配套30 mm灌水定额,无膜滴灌处理配套54 mm灌水定额可取得较好的效果。【结论】提高灌水定额可以在一定程度上弥补无膜种植模式引起的籽棉产量降低,但会降低灌溉水利用效率。研究结果可为无膜滴灌植棉技术在当地的推广提供参考。

改良剂施用对硫酸盐型棉田产量及土壤盐渍化参数的影响

探究施用酸碱平衡护理剂改良盐渍化棉田的效果与机制,为盐碱地改良和棉花稳产提供理论依据。本研究以新疆沙湾县硫酸盐型棉田为试验对象,于2021—2022年设置施用酸碱平衡护理剂和对照两个处理,监测0~20 cm土层土壤的电导率和pH值,测定棉花长势、产量和土壤盐分指标。结果表明:(1)相较于对照,酸碱平衡护理剂处理的棉花出苗率显著提高4.93~6.13个百分点。(2)2021、2022年酸碱平衡护理剂处理籽棉产量分别为5210.06、6815.43 kg/hm^(2),较对照显著提高25.98%、8.87%。(3)2021年酸碱平衡护理剂处理10~20 cm土层土壤钠吸附比值较对照降低0.077,2022年0~10、10~20 cm土层土壤分别较对照降低0.204、0.173。(4)土壤全盐变化量与SO_(4)^(2-)变化量呈显著正相关(P<0.05)、与Na^(+)变化量呈极显著正相关(P<0.01);籽棉产量变化量与单株成铃数变化量呈显著负相关(P<0.05),与土壤电导率变化量呈极显著负相关(P<0.01),与单铃重变化量呈极显著正相关(P<0.01)。综上表明,硫酸盐型棉田施用酸碱平衡护理剂能够降低土壤盐分,提高籽棉产量。

外源物浸种对苗期遭遇冷害棉花生长发育、产量及品质的影响

以‘中棉113’为试验品种,施用海藻糖、褪黑素和抗坏血酸对棉花进行浸种预处理,在棉花出苗期间遭受低温冷害后,比较3种外源物处理的棉花成苗情况、主要农艺性状、生物量积累、产量及其构成因素及纤维品质性状间的差异。结果表明:与CK处理相比,外源物处理的棉花成苗率显著提高1.3%~6.1%;株高、茎粗和果枝台数分别显著提高8.1%~9.2%、10.1%~14.6%和13.7%~22.2%;生物量显著增加1.6%~20.9%,生物量在库(蕾、花、铃)的分配比例提高3.3%~16.4%;籽棉产量显著提高11.7%~18.4%;棉花纤维品质表现较好,棉花纤维上半部平均长度和断裂比强度均达到29 mm以上和29 cN·tex^(-1)以上,马克隆值为B级。综上所述,外源物浸种处理可以显著提高受灾棉花的成苗率,促进棉花植株的生长发育和生物量的积累与分配,提高产量,其中,100μmol·L^(-1)褪黑素浸种的效果优于其余2种外源物浸种。

赣北棉区棉花干物质积累特征和产量对减氮措施的响应

为探究减氮措施对棉花干物质积累特征及产量的影响,设置常规施氮(N_(1),施氮量345 kg·hm^(-2))、减氮20%(N_(2),施氮量276 kg·hm^(-2)),减氮20%其中配施10%有机肥(N_(3),施氮量276 kg·hm^(-2),化肥与有机肥配施比例9∶1)和不施氮(N4)共4个处理,分析棉花干物质积累特征参数、产量、养分含量对不同减氮措施的响应。结果表明,与N_(1)处理相比,N_(2)与N_(3)处理吐絮期棉花生殖器官干物质分配比例显著增加10.29%、15.10%,干物质积累时长缩短10.97%、13.27%,生殖器官干物质积累快增期持续时长增加11.76%、90.04%,加快了棉花生育进程;N4处理干物质积累平均速率降低45.30%,干物质积累最大速率出现时间延缓。2年平均籽棉产量与经济效益均以N_(3)处理最大,分别为3496.87 kg·hm^(-2)和22956.64元。因此,N_(3)处理即减氮20%并配施10%有机肥处理为赣北棉区高产、节肥并具有最佳经济效益的减氮措施。以上结果为降低赣北棉区氮肥投入量提供指导意义。

施氮对亏缺灌溉措施下棉花生长、养分吸收及产量的影响

研究节水灌溉措施结合氮肥管理对棉花干物质积累、生理响应、养分吸收和产量的影响,为干旱区棉花增产和水肥高效利用的农艺实践提供理论依据。以棉花‘新陆早72’为试验材料,研究了在2种灌溉处理下(正常灌溉,W1;亏缺灌溉,W2)不同施氮量(210 kg·hm^(-2),N1;300 kg·hm^(-2),N2;390 kg·hm^(-2),N3)对棉花干物质积累、光合生理特性、养分吸收、抗氧化防御、渗透调节及产量的影响。结果表明:与正常灌溉相比,亏缺灌溉通过降低干物质积累、净光合速率、抗氧化酶活性以及养分吸收降低了籽棉产量。与亏缺灌溉下进行适量施氮相比(W2N2),增加施氮量处理(W2N3)的净光合速率和叶面积指数分别提高12.5%和10.9%,抗氧化酶活性、渗透调节物质分别提高13.6%、42.6%,这些过程减轻了亏缺灌溉对棉花生长造成的伤害,促进养分吸收和干物质积累,最终籽棉产量提高5.6%。此外,与正常水肥管理处理(W1N2)相比,亏缺灌溉后增加施氮量(W2N3)并没有降低籽棉产量,反而通过改善冠层光合能力、抗氧化防御及渗透调节能力延长了干物质持续积累时间,使植株提前3~4 d结束生育进程。综上所述,在干旱区开展棉花节水灌溉措施时,建议在常规施氮量的基础上再增加30%,该施氮量可以在保证棉花不减产的同时节约更多的灌溉水,并且该措施对干旱区滴灌棉花生产中的节水增效和可持续生产具有重要意义。

水分亏缺下有机无机肥配施比例对棉花水氮利用效率的影响

【目的】探究不同水分条件下有机无机肥配施对棉花水氮利用效率和产量的影响,为河西走廊棉区合理利用有机肥提供理论依据。【方法】于2020-2021年进行田间定位试验,采用裂区试验设计,主区为充分灌溉(W1)和亏缺灌溉(W2);副区为不施肥(CK)、单施化肥(CF)、25%有机肥+75%化肥(OF1)、50%有机肥+50%化肥(OF2)和75%有机肥+25%化肥(OF3),分析不同水分条件下施肥对棉花生育期土壤含水量、阶段耗水量、干物质和氮素积累及转运分配、水氮利用效率、籽棉产量和经济效益的影响。【结果】棉花籽棉产量和水氮利用特征受不同水肥处理及交互作用的显著影响。亏缺灌溉下棉田土壤含水量、总耗水量、植株干物质积累量、氮素积累量和籽棉产量显著下降,而水分利用效率显著提高。适宜的有机无机肥配施处理能够提高0-40 cm土层土壤含水量,降低棉花苗期和蕾期耗水,增加花铃期耗水量,提高棉花干物质和氮素积累量,并促进其向生殖器官中分配。充分灌溉条件下,25%有机肥配施处理(OF1)籽棉产量最高,两年平均较单施化肥(CF)提高10.5%;50%有机肥配施处理(OF2)与单施化肥(CF)无显著差异,但75%有机肥配施处理(OF3)显著降低。25%有机肥配施处理在各施肥处理中水氮利用效率最高,其中水分利用效率、氮素利用率和氮肥农学利用率分别较单施化肥提高8.9%、14.3%和28.9%。亏缺灌溉条件下,有机无机肥配施处理籽棉产量均高于单施化肥,其中50%有机肥配施处理表现最高,两年籽棉平均产量较单施化肥提高12.9%,同时50%有机肥配施处理水氮利用效率也表现为最高,其中水分利用效率、氮素利用率和氮肥农学利用率分别较单施化肥提高6.3%、35.5%和31.6%。【结论】适宜比例的有机无机肥配施能够协调土壤-作物水分养分供需关系,提高棉花籽棉产量和水氮利用效率。综合考虑产量、水氮利用效率和植棉效益,25%有机肥配施处理为河西走廊棉区适宜的有机肥配施模式。

水氮调控对棉花生理性状及产量的影响

水分和氮素是影响棉花生长发育和产量的主要因子,为探究水分和氮素对棉花形态、生理特性以及产量的调控效应,本研究以‘农大棉36号’为材料,设置干旱胁迫(W1,相对含水量为45%±5%)和正常供水(W2,相对含水量为70%±5%)两个水分条件以及不施氮肥(N0)、低氮[N1,69mg(N)∙kg^(-1)]、常规施氮[N2,138mg(N)∙kg^(-1)]3个氮素水平,分析不同水分和氮肥条件下棉花地上部和根系形态、光合性状、抗氧化酶活性、氮代谢酶活性以及产量的变化。结果表明,与W2处理相比,W1处理显著抑制了棉花生长,降低了棉花株高、茎粗、叶面积以及总根长、总根表面积、平均根直径(P<0.05),显著增加了超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性,降低了相对叶绿素含量(SPAD)、最大光化学效率(F_(v)/F_(m))和光合能力,从而造成棉花产量下降(P<0.05);与N2处理相比,N0和N1处理上述指标均显著降低。干旱胁迫下,常规施氮处理比不施氮肥和低氮处理促进棉花地上和地下生长,显著提高主茎叶SPAD、净光合速率和F_(v)/F_(m)(P<0.05),增强抗氧化酶(SOD、POD、CAT)和氮代谢酶(GS和NR)活性(P<0.05),减轻干旱胁迫对棉花生长造成的抑制,提高棉花产量。在低氮条件下,正常供水比干旱胁迫处理亦促进棉花的生长,增强光合作用和氮代谢酶活性,减缓了低氮胁迫对其产生的不利影响,提高产量(P<0.05)。因此,可通过增施氮肥提高干旱胁迫下的棉花产量,亦可通过适当增加灌水量提高低氮胁迫下的棉花产量,本研究为明确氮素胁迫和水分胁迫下合理的水肥管理提供了理论依据。

播期和种植密度对不同熟性棉花生理特性及产量的影响

以棉花早熟品种‘湘K27’和‘JX0010’为试验材料,以晚熟品种‘HN127’为对照,分别设置2个种植密度(2000株/(667 m^(2)))、3000株/(667 m^(2))和2个播期(5月25日、6月5日),于2021年在湖南农业大学耘园基地进行大田试验,通过测定其生理生化指标和产量构成因素,研究不同种植密度和播期对棉花产量的影响。结果表明:早熟直播棉较晚熟品种SPAD值高;晚熟品种SOD活性总体高于早熟品种,晚播较早播在蕾期到花铃期时能显著提高棉花的SOD活性;从POD活性来看,早熟棉较优;从MDA含量来看,在早播和高种植密度条件下,营养生长期(蕾期)以晚熟品种表现较佳,生殖生长期(花铃期)以早熟品种‘JX0010’最优;品种极显著影响单铃质量、单株铃数和产量,且均表现为早熟品种优于晚熟品种。综合分析,早播有利于提高早熟棉产量,增加种植密度虽在一定程度上可提高产量,但增产潜力不大。

不同土壤盐分胁迫对棉花氮素利用效率及生长的影响

为明确土壤盐分胁迫对棉花氮素高效利用及生长发育的影响,本研究应用~(15)N同位素技术开展田间试验,设计土壤弱(2.0 g/kg)、轻度(6.5 g/kg)、中度(13.0 g/kg)和重度(17.9 g/kg)4种盐渍化水平处理,分析土壤盐分胁迫对棉花干物质量、总氮含量、~(15)N利用效率、生长指标及产量的影响。结果表明,当胁迫从土壤弱盐渍化增加至轻度盐渍化水平时,棉花干物质量、总氮含量和~(15)N利用效率显著提高,并且棉花茎与果实对氮素的吸收征调能力总体增强,当土壤盐分进一步增加至中度盐渍化水平时棉花干物质量、总氮含量和~(15)N利用效率显著降低;相关性分析表明,棉花~(15)N利用效率与出苗率呈极显著正相关(P<0.01),土壤轻度盐分胁迫下籽棉产量最高,为6 456.9 kg/hm~2;中度土壤盐分胁迫导致幼苗生长以及40~60 cm土层棉花根系受阻,与轻度盐分胁迫相比棉花出苗率降幅33.1%,籽棉产量降幅37.7%。综合以上测定指标及产量,北疆地区合理的土壤盐氮调控措施应包括严格的控制田间地下水位、科学的进行机械整地和不间断的培肥土壤。

水氮运筹对新疆无膜滴灌棉花生长发育及土壤温室气体排放的影响

【目的】探究水氮运筹对新疆无膜滴灌棉田棉花生长发育、水氮利用效率及土壤温室气体排放的影响。【方法】设置2个灌水定额(W1:450 m^(3)·hm^(-2),W2:540 m^(3)·hm^(-2))和3个施氮量(150、225、300 kg·hm^(-2)纯氮),分析不同水氮条件下土壤和植株全氮含量、棉花株高与茎粗、籽棉产量、水分与氮素利用效率及土壤温室气体排放的差异。【结果】225 kg·hm^(-2)和300 kg·hm^(-2)施氮量下,不同生育时期W1的0~80 cm土层平均全氮含量高于W2处理。同一施氮量水平下,W1处理的土壤CO_(2)、CH_(4)、N_(2)O累积排放量,全球增温潜势(global warming potential,GWP),土壤温室气体排放强度(greenhouse gas emission intensity,GHGI)及水分利用效率均高于W2处理。W1灌溉水平下,苗期和蕾期0~80 cm土层平均全氮含量、不同生育时期棉花的株高与茎粗、籽棉产量、水分利用效率均随施氮量的增加而增加,土壤CO_(2)和CH4累积排放量、GWP、GHGI和氮肥偏生产力均随施氮量的增加而降低,而植株全氮含量随施氮量的增加呈现先升高后降低的趋势。W2灌溉水平下,植株全氮含量、籽棉产量和水分利用效率均随施氮量的增加呈先升高后降低的趋势,土壤CO_(2)及CH_(4)累积排放量、GWP和氮肥偏生产力均施氮量的增加而降低,而棉花茎粗和株高随施氮量的增加而增加。通过拟合分析发现,W1与W2处理的籽棉产量拟合曲线在施氮量为278.07 kg·hm^(-2)时相交。【结论】在水资源短缺的新疆南疆地区,450 m^(3)·hm^(-2)灌水定额和300 kg·hm^(-2)施氮量是无膜滴灌棉花节水、增产、减排的高效水氮施用模式。

棉花夏播短季栽培高产高效生产模型研究

研究栽培措施与棉花产量之间的关系,寻找其最佳的生产管理方案,是夺取单位面积高产、提高经济效益的重要途径。本试验以早熟品种JX0010为供试材料,于2018—2019年在浏阳永和设定施氮量、种植密度、播期三个栽培因子,采用311-A最优二次回归设计,对棉花的农艺性状、干物质、光合作用、产量和品质等进行一系列的研究,建立适合长江流域棉区短季栽培的高产、高效数学模型,以在生产上推广应用。结合试验过程中的成本、收益及早熟情况进行综合分析与评价,结果分析表明,最高产量模型组合及最优生产模型推行方案为:露地直播,5月20日左右播种,施氮量为225 kg/hm^(2),种植密度为5.25万株/hm^(2),可获得平均皮棉产量为1372.16 kg/hm^(2),10月10日收花截止,按生育期140 d计算,日均皮棉产量为9.801kg/hm^(2),用工日为135个/hm^(2),植棉效益为6783.77元/hm^(2)。

亏缺灌溉对中国棉花产量和灌溉水分生产力影响的元分析

【目的】亏缺灌溉是节水农业的一种有效灌溉方式。定量分析亏缺灌溉对我国棉花产量及灌溉水分生产力的影响,为亏缺灌溉在我国进一步推广应用提供参考。【方法】整合2010―2022年已发表的53篇文献,采用元分析方法,定量评估亏缺灌溉条件下不同因素对中国棉花产量和灌溉水分生产力的影响特征。【结果】与充分灌溉相比,亏缺灌溉下籽棉产量平均降低16.2%,而灌溉水分生产力平均增加32.2%。亚组分析表明,在亏缺灌溉条件下我国西北内陆棉区的灌溉水分生产力提升最高,其中新疆地区的减产幅度较小效果最好;降水量相对较少的地区及大田栽培条件下能更有效地利用亏缺灌溉的水分;年平均气温≥10℃的地区,采用干播湿出,适当增加灌溉次数能够有效降低亏缺灌溉导致的减产风险;土壤容重<1.5 kg·cm-3的土壤条件下,亏缺灌溉棉花的减产风险低于高容重的土壤环境;在灌水量为充分灌溉的80%~100%,氮、磷和钾施用量分别为200~300 kg·hm^(-2)、150~200 kg·hm^(-2)和100~150 kg·hm^(-2)的条件下能够有效促进水分利用且降低减产风险。【结论】建议在我国温度相对较高的西北干旱地区,采用干播湿出的棉花种植方式以节水稳产,实施轻度亏缺灌溉,适当增加灌水次数,适量施肥,降低亏缺灌溉对棉花生产的影响。