Optimum Seed Rate and Nitrogen Fertilizer Requirement of Rice Under Semi-deepwater Ecosystem

The effect of varying seed rates (100–1000 seeds m⁻²) and nitrogen fertilizer (0–60 kg N ha_-1) applied either in a single basal dose or in splits was investigated on a tall elongating, photosensitive rice variety, Nalini, under semi-deepwater conditions (0–100cm) during 1993 and 1994 at Cuttack, India. Seedling emergence was higher in 1993 (53.9 %) than in 1994 (44.1 %) and it increased proportionately with increasing seed rate, Increase in the number of tillers and panicles m⁻² at higher seed rates was associated with a corresponding decrease in panicle weight. Regression analysis indicated a decrease of 0.91–1.28g in panicle weight for an increase of 100 panicles m⁻². The grain yield of rice was significantly higher at 400 seeds m⁻² in 1993 and at 600 seeds m⁻² in 1994 than at low seed rates but further increase in seed rate did not increase the yield. Application of N fertilizer increased the panicle number and thereby grain yield significantly. The effect of basal and split applied N at active or maximum tillering stages as well as between 30 and 60 kg N ha⁻¹ was not significant on the grain yield. The results suggest that a basal dose of 30kg N ha⁻¹ and seeding density of 400–600 seeds m⁻², resulting in 40–50 % seedling emergence and 150–200 panicles m⁻², each with 2.0–2.5 g weight, may be adequate for optimum productivity of rice under semideepwater conditions.     

不同氮素用量对甜荞麦干物质和养分积累及分配的影响

为了掌握甜荞麦适宜施氮量,研究不同供氮水平对甜荞麦干物质和养分积累及分配影响的规律。采用田间小区试验的方法,设置5个氮素水平N_0、N_1、N_2、N_3和N_4(0,30,60,90,120 kg/hm~2),研究了甜荞麦不同器官干物质和养分积累量及分配比例的变化。结果表明,甜荞麦干物质积累总量随着施氮量的增加呈先增后降的趋势,N_2处理干物质积累总量最大,但N_3处理籽粒中干物质积累量和分配比例最大。荞麦籽粒氮、磷和钾含量随着氮肥用量的增加先增后降,N_3处理籽粒中氮、磷、钾养分含量最大;增加施氮量可提高氮、磷和钾在籽粒中的分配比例,但会降低它们在茎和叶中的分配比例。甜荞麦生产100 kg籽粒平均需吸收N 7.09 kg、P_2O_5 4.15 kg、K_2O 8.74 kg,养分比例为1∶0.59∶1.24,养分生产效率随着氮肥用量的增加先增后降,N_3处理的氮磷钾养分生产效率均达最高。随着氮肥用量的增加,氮磷干物质生产效率先增后降而后又上升,钾的干物质生产效率逐渐上升,N_4处理的氮磷钾干物质生产效率均达最高。综合考虑干物质和养分积累及分配因素,施氮量90 kg/hm~2为甜荞麦适宜氮肥用量。     

小麦/玉米轮作模式下氮肥运筹对土壤氮素残留及下茬作物的影响

为明确不同类型土壤小麦/玉米轮作模式下土壤氮素残留对后茬作物的影响,本研究在砂壤土和砂姜黑土2种土壤条件下,分别对小麦/玉米季氮肥运筹对土壤氮素残留及其对下茬作物的影响展开研究.研究结果表明:施用氮肥提高产量的同时,提高了小麦、玉米收获后土壤氮素残留量.随着追氮后移,土壤氮素残留量提高,特别是提高了残留氮素在上层土壤中...     

Phosphorus Accumulation and Translocation in Wheat as Affected by Cultivar and Nitrogen Fertilization

To improve nutrient management strategies in wheat more information is needed about the interaction effects among nutrients in their uptake and redistribution in the plants, in relation to different genotypes. Therefore, two bread ( T. aestivum L.) and two durum ( T. durum Desf.) winter wheat cultivars were grown in the field for 2 years (1986, 1987) in a silty-clay soil under different nitrogen (N) levels, in Northern Greece. Nitrogen at a rate of 150 kg ha⁻¹ was applied before planting or 100 kg ha⁻¹ before planting and then 50 kg ha⁻¹ at early boot stage. Cultivar differences in phosphorus (p) concentration were observed only in vegetative parts but not in the grain. Maximum p accumulation was observed either at anthesis or at maturity. During grain filling dry matter and p accumulation in the grain followed almost the same pattern. Phosphorus translocation efficiency of the cultivars at the 2 years ranged from 70.7 to 84.3 % and the amount of p in the grain derived from translocation 52 to 100 %. Phosphorus translocation efficiency was weakly correlated with p content in grain only in 1986, while phosphorus harvest index (PHI) was positively correlated with harvest indst (HI) both years (r = 0.82** in 1986 and 0.75** in 1987). Nitrogen application mainly affected p accumulation of the cultivars via its effect on biomass production. The split N application promoted slightly the p uptake in 1987 and this resulted in the reduction of both the contribution of the translocated p to the grain and the efficiency of p utilization for total biomass. Results indicated that p accumulation and translocation and the efficiency of p utilization in wheat were mainly determined by the genotype in relation to environmental condition of growth.     

不同施氮量对川东北地区水稻产量及氮肥利用率的影响

针对川东北丘陵部分稻田氮肥用量偏高的状况,选择重穗型品种冈优188(V1)和稳数型品种阳鑫优1号(V2)为试验材料,设置N0、N1、N2、N3等4个施氮水平,2008年～2009年进行了试验,分析不同施氮量对一季中稻产量和氮素利用率的影响.结果表明,不同施氮量对不同类型品种水稻的产量影响不同:施氮量为N1 (105 kg/hm2)时,冈优188产量为8623.16kg/hm2,达到较高的经济效益;施氮量为N3(195kg/hm2)时,阳鑫优1号产量最高,达8522.49 kg/hm2.随着施氮量的增加,水稻吸收氮素的总量增加,氮素吸收利用率、干物质生产效率、稻谷生产效率随之降低.在同一施氮水平上,冈优188的氮素农学利用率、生理利用率均高于阳鑫优1号,而氮素吸收利用率则低于阳鑫优1号.     

Grain Yields and Grain Nitrogen Concentration of Corn as Influenced by Fertilizer Nitrogen Rate

Knowledge of optimum fertilization for com production is required to increase crop yields while minimizing fertilizer costs. Field experiments were carried out from 1988 to 1993 to study the effects of fertilizer N rates on yield and N concentration of corn ( Zea mays L.) grain on a clay soil in Quebec. Grain yields and grain N concentrations generally followed a exponential relationship with increasing N fertilizer rates. The critical grain N concentration, defined as that associated with the highest grain yield, occurred at 285 kg N ha^-1 for all years except 1969 when it occurred at 170 kg N ha^-1. The critical grain N concentrations and grain yields over the years were found to be linearly related. The relationship between the critical grain N concentration and grain yield could serve as a diagnostic tool for N applications.     

湘中南地区烟稻轮作条件下烟草作物的施肥效应与肥料效应函数研究

为了建立适合湘中南双季稻地区烟稻轮作制条件下烤烟作物的平衡施肥模型,确定烟草的合理施肥量,运用联合国粮农组织(FAO)“3414”试验方案,稍作修改,通过田间小区试验,探讨湘中南双季稻地区烟稻轮作制条件下烤烟作物施用氮磷钾肥的增产效应及其最佳施肥量,以为烤烟作物的科学施肥提供科学依据和技术支撑。结果表明：烤烟作物的地力贡献较小,无肥区产量仅占氮磷钾平衡施肥处理（处理6）产量的34.6%~39.4%;增产效果居首位的是氮肥,农大,永州,常宁3个试验点分别增产719.6 kg/hm2、1109.7 kg/hm2和441.0 kg/hm2;运用“3414”试验设计方案得到的各试验点的二元二次肥料效应模型拟合均不成功,农大点推荐施肥宜使用一元二次方程模型,据此所得最佳施肥量分别为N 159.8 kg/hm2,P2O5 86.1 kg/hm2,K2O 152.2 kg/hm2;永州点推荐施肥宜使用三元二次方程模型,据此所得最佳施肥量分别为N 175.2 kg/hm2,P2O5 52.1 kg/hm2,K2O 278.3 kg/hm2;常宁点推荐施肥宜使用一元二次方程模型,据此所得最佳施肥量分别为N 178.7 kg/hm2,P2O5 107.8 kg/hm2,K2O 279.2 kg/hm2;综合各函数的最佳施肥量得到湘中南双季稻地区的烟草作物的施肥决策：烤烟作物对氮、磷、钾养分的最佳产量施肥量为N 172.2 kg/hm2,P2O5 93.3 kg/hm2,K2O 300.0 kg/hm2。     

不同追施氮肥量对南疆陆地棉SPAD值及干物质积累与分配的影响

为明确追施不同氮肥量对陆地棉SPAD值及干物质积累与分配的影响,在南疆巴州地区以当地主栽品种‘巴43541’为材料,设置4个追施氮肥水平,分别为不追施氮(N0)、减施50%常规追施氮肥(N1)、常规追施氮肥(N2)、增施50%常规追施氮肥(N3),分析不同追施氮肥量对叶片SPAD值、干物质积累与分配、产量以及氮肥利用的影响。结果表明,减施50%追施氮肥量能增加陆地棉各生育期的SPAD值和SPAD积累值,且生殖器官干物质转化比例最高为60.53%,产量为6581.32 kg/hm²,相比于其他处理增产1.4%～16.5%,氮肥偏生产力和氮肥农学利用率均显著高于其他处理。减施50%常规追施氮肥处理较其他处理增产虽然不显著,但是能够显著增高氮肥偏生产力和氮肥农学利用效率,可考虑在生产实践中应用。     

不同水分条件下缓/控释氮肥对水稻干物质量和氮素吸收、运转及分配的影响

为探究缓/控释肥在不同水分条件下提高氮素利用率及增产机制。本研究以杂交中稻F优498为试验材料,在180 kg hm^-2施氮量基础上,采用两因素裂区设计: 主区设控灌、干湿交替灌溉、传统灌水灌溉3种水分管理方式,副区设尿素一道清、尿素常规运筹、硫包膜缓释肥、树脂包膜控释肥4种氮肥种类,研究缓/控释肥和水分管理方式对水稻干物质量和氮素吸收、运转、分配和产量的影响及其互作效应。结果表明, 缓/控释肥和水分管理方式对水稻主要生育期干物质量和氮吸收、转运、分配及产量具显著影响及互作效应,产量构成因素与氮素在结实期转运总量及其分配呈显著正相关。干湿交替灌溉和缓/控释肥均能提高干物质量、氮素吸收及产量并表现出显著互作效应,施用缓/控释肥氮素表观利用率达42%~53%,相较于尿素一道清和传统的尿素常规运筹,氮肥偏生产力提高6%~23%,氮素农学利用率提高26%~71%,增产8%~19%。控灌条件下,缓/控释肥处理氮素有效性高,保证足穗、促进重穗;干湿交替灌溉条件下缓/控释肥处理能保持氮素的高效释放,有利于高产群体的形成,从而提高稻株氮素积累、协调氮素分配;淹水灌溉条件下,缓/控释肥处理无效分蘖减少,氮素入渗、淋溶降低,成穗率提高。综合产量与氮素吸收、运转的表现,干湿交替灌溉条件下施用缓控释肥为本试验最佳处理,能有效提高氮素利用率,促进高产形成。     

枸溶性钾肥对玉溪烟叶及根区土壤养分含量的影响

为解决限制玉溪烟叶钾含量无法进一步提升,烟叶钾钙镁含量不均衡的问题,取云南玉溪2个试验小区,采用大田试验设置5个施肥处理（农民常规(T₁)、无钾(T₂)、硫酸钾(T₃)、枸钾1/4代替(T₄)、枸钾1/2代替(T₅)）,研究不同肥料配方对烟叶及根区土壤养分的影响。结果表明,塔甸地区T₄处理、新平地区T₄~T₅处理的烟叶产量较高,提升幅度为3.43%、49.7%、61.1%。2个地区施用枸溶性钾肥(T₄)可在进一步增加烟叶钾钙含量的基础上,增加烟叶镁含量、降低硫含量,使烟叶钾钙镁含量的比例更加协调,分别为1.4、1.1。施用枸溶性钾肥可显著提升根区土壤有效钙镁含量,2个地区的T₄处理可分别提升37.6%、31.8%的有效钙,而T₅处理可分别提升112.1%、46.4%的有效镁。综合不同施肥配方对烟叶及土壤养分含量的影响认为,枸钾1/4代替处理在塔甸和新平得到较好的效果,烟叶品质、根区土壤速效养分得到有效提升。     

土壤改良剂对中稻-再生稻产量与氮肥利用的影响

为了探究土壤改良剂对水稻产量和氮肥利用的影响,为中稻-再生稻增产与肥料高效利用以及稻田次生障碍阻控提供理论支撑。以准两优608(2016年)和晶两优华占(2017年)为试验材料,设施用过氧化钙(CaO₂)、施用生物石灰(Bi-CaO)、施用硅肥(SiO₂)、常规施肥(NPK)和不施肥(NF)5个处理。分别测定了水稻产量和氮肥利用相关的指标。结果表明,施用土壤改良剂显著增加中稻-再生稻系统产量,与常规施肥(NPK)相比较头季产量增幅达7.37%～17.78%,再生季可增产493.3～982.2 kg/hm²。施用土壤改良剂显著提高中稻-再生稻有效穗数与头季结实率和穗粒数,且显著增强其各生育期干物质积累。土壤改良剂显著提高中稻-再生稻植株氮素吸收与积累,且后期以施用过氧化钙(CaO₂)效果最佳。施用土壤改良剂显著促进中稻-再生稻系统氮肥高效利用,与NPK相比较施用改良剂处理氮肥偏生产力(NPFP)、肥料氮贡献率(NCT)、氮肥农学利用率(AE_N)和氮素回收率(RE_N     

播期、密度和施氮量对稻茬小麦光明麦1号氮肥表观利用率的调控

提高氮肥利用效率是当前小麦生产中重要的研究方向之一。本研究以光明麦1号为试验品种,利用两年的田间试验结果,采用二次正交旋转组合设计建立回归模型,分析稻茬小麦的氮肥当季表观利用率(utilization rate of nitrogen fertilizer,NUR)受播期、密度、施氮量组合的调控效应。结果表明,对小麦NUR效应表现为氮肥播期密度。在试验条件下,实现高产和高NUR目标,三因素有多种组合模式,其中播期10月28日至11月2日+密度160~180万株hm–2+施氮量200 kg hm–2的组合,其产量为6800~7200 kg hm–2,NUR大于42.0%(最大值为44.8%),可靠度达到95%;播期10月21日至27日+密度120~150万株hm–2+施氮量190~225 kg hm–2组合,其产量为6200~7000 kg hm–2,NUR达41.0%以上;播期11月3日至11日+密度210~240万株hm–2+施氮量190~210 kg hm–2组合,其产量为5900~7250 kg hm–2,NUR达39.0%以上。     

三角形强化栽培模式下氮肥运筹对II优498产量及氮肥利用的影响

以大穗型杂交籼稻II优498为材料,在三角形强化栽培(triangle-planted system of rice intensification, TSRI)适宜的密度和秧龄条件下,研究施氮量和施肥比例对TSRI结实期叶面积、光合作用以及干物质积累与转运的影响,并探讨花前期物质积累转运与花后期光合生产在产量形成过程中的作用,同时探索既能提高产量又能减少氮肥损失的氮肥运筹措施。结果显示,TSRI下,除蜡熟期叶面积指数(leaf area index, LAI)外,施氮量和施肥比例对光合作用和LAI有显著运筹作用; 增施氮肥和氮肥后移可以显著提高齐穗期和蜡熟期剑叶净光合速率,LAI则随施氮量和氮肥后移程度增加多呈抛物线趋势。TSRI下施氮量和施肥比例共同提高总颖花数增加产量,而施氮量和施肥比例又各自通过提高千粒重和结实率来增加产量。TSRI下,花前干物质积累量、物质转运量、转运率与产量极显著正相关,施氮量为150 kg hm^-2, 穗肥占总施氮量的30%的处理在显著增大花前干物质积累量和籽粒灌浆期间向穗部的转运量实现高产的同时显著提高氮肥农学利用率和生理利用率,是TSRI平衡产量与氮肥利用率的最优氮肥运筹组合。     

稻田养鱼与氮密互作对土壤肥力、水稻产量及其养分累积的影响

为了给稻田养鱼的施肥管理提供科学依据。试验以杂交中稻新品种‘内6优106’为材料,在3个鱼-氮处理(CK:不养鱼+不施氮、F:养鱼+不施氮、FN:养鱼+施氮150 kg/hm²)和4个本田栽秧密度下,研究稻田养鱼与氮密耦合对土壤肥力、水稻产量及其养分吸收累积的影响。结果表明:稻田养鱼后的有机质显著提高、氮素能维持平衡、磷钾素则显著下降。鱼氮处理水稻产量、地上部干物质及氮、磷、钾累积的总体趋势表现为FN>F>CK,FN与F分别比CK显著增产22.98%和13.43%。栽秧密度在9.0万～22.5万穴/hm²范围内稻谷产量无显著差异,干物质和氮累积影响随密增加而增加。每1000 kg稻谷的地上部植株氮、磷、钾素的需要量分别为10.24～16.74、1.31～2.72、34.38～56.49 kg/hm²。中高产养鱼稻田在施肥管理上应控制氮肥和增施磷钾肥。     

土壤镉含量影响水稻产量与稻穗镉累积分配的品种间差异

以谷粒镉（Cd）积累能力不同的3个晚稻品种（天优华占、星2号和湘晚籼13号）为材料,在人为设置的3个土壤Cd含量条件下,研究土壤镉含量提高对水稻产量与稻穗镉累积分配特性的影响及其品种间差异。结果表明：（1）土壤Cd含量提高使水稻产量下降,在添加1.0mg/kg Cd时各品种均显著减产,以天优华占降幅最大;土壤Cd含量提高对水稻产量构成因素的影响具有品种间差异,但其使各品种产量下降的主要原因基本一致,即主要由有效颖花数、结实率与收获指数下降导致。（2）稻穗与谷粒各部分Cd含量均随土壤Cd含量提高而显著提高,但并不呈直线增长趋势,3个品种的提高幅度表现天优华占>星2号>湘晚籼13号趋势。（3）稻穗Cd累积量随土壤Cd含量提高而显著提高,品种间稻穗Cd累积量呈天优华占>星2号>湘晚籼13号趋势。（4）稻穗Cd主要累积在实粒中,但实粒Cd所占比例随土壤Cd含量提高呈下降趋势,3个品种实粒Cd所占比例呈星2号>天优华占>湘晚籼13号趋势。可见,土壤Cd含量提高对水稻产量与稻穗Cd累积分配的影响具有明显的品种间差异,Cd污染程度不同的稻田应因地制宜选择水稻品种。     

施氮对大豆根瘤生长和结瘤固氮的影响

采用框栽试验研究了施氮对大豆根瘤生长和结瘤固氮的影响,结果表明,施氮对大豆根瘤形成、生长和固氮能力有显著影响,随着N用量的增加,根瘤干质量、根瘤数量呈现先逐渐增加而后降低的趋势,而固氮酶活性和豆血红蛋白含量则表现为持续下降的趋势,适量施氮对根瘤生长有显著的促进作用,当氮素供应不足时则会抑制根瘤的生长,但当氮素供应过量时也会抑制根瘤的形成.从根瘤干质量和根瘤数量来看,各处理间表现为N100>N200>N50>N25>NO,以N100处理下根瘤干质量最大,根瘤数量最多,显著高于不施氮(N0)和其他施氮处理,从不同生育时期来看,根瘤干质量表现为从苗期到花期再到鼓粒期,大豆根瘤的数量呈现出先明显增加后逐渐减少的趋势,高峰出现在花期,而根瘤数量表现为花期>苗期.施氮显著抑制了固氮酶活性和豆血红蛋白含量,随施氮水平的增加,固氮酶活性和豆血红蛋白含量显著降低,表现为NO>N25>N50>N100>N200,表明施氮使大豆根瘤的固氮效率显著降低,因此,从大豆固氮效率来讲,施氮对大豆根瘤固氮具有抑制作用.方差分析结果表明,施氮和不施氮处理间均达到了5%的差异显著水平.因此,从大豆固氮和氮肥施用平衡的角度来看,应适量施用氮肥,既可以充分利用大豆的固氮功能,节约氮肥,又可以获得较高的产量.     

Effects of Cropping System, Seed Bed Management and Fertility Interactions on Biomass of Crops Grown on a Vertisol in the Central Highlands of Ethiopia

In the Ethiopian highlands, where integrated crop and livestock production takes place, the inadequate supply, in both quantity and quality, of feeds during the year is a major constraint. Native pastures and crop residues are the major feed sources, but their quality is often poor. Integration of forage legumes in the cropping system is one alternative to improve the fodder quality. Results of field work conducted over two seasons in order to assess and evaluate the potential yields of crops, crop/forage combinations and rotation systems on a Vertisol under two seed bed preparation systems showed that intercropping wheat with clover or sequential cropping of an oat/vetch mixture followed by chickpea provided high-quality fodder; the effect was greater under fertilized conditions. In addition, where monocropping treatment was tested, legume–cereal rotation resulted in higher grain and fodder yield when compared to cereal–cereal rotation. The study also showed that two short-duration crops could be produced in sequence per year. It is therefore suggested that the Vertisols in the Ethiopian highlands could provide a good opportunity for longer period cropping using improved food and forage crops, thereby improving the availability and quality of animal feed and protecting the land against erosion.     

Time Course of Nitrogen in Soil Solution and Nitrogen Uptake in Maize Plants as affected by Form and Application Time of Fertilizer Nitrogen

Field experiments with silage maize were conducted in 1987 and 1988 on a loess-derived Luvisol in southwest Germany. Four nitrogen fertilizer treatments were compared: application of preplanting NH₄ N (plus a nitrification inhibitor, dicyandiamide as Didin) and preplanting NO₃-N, split application of NO₃-N (preplanting and side dressed 45 days after planting) and a control without nitrogen fertilizer in 1987 and with 64 kg N ha^?1 as calcium ammonium nitrate in 1988. The total amounts of soil mineral nitrogen (N_min+ fertilizer N) were 200 kg N ha^?1 in 1987 and 240 kg N ha^?1 in 1988. Suction cups and tensiometer were installed at five depths and samples were taken in regular intervals. Nitrate concentrations in the suction solution steeply increased at 15 cm and 45 cm soil depth 3-4 weeks after fertilizer application (1987 up to 160mgNl^?1; 1988 up to 170mgN l^?1) and steeply decreased up to 75 cm depth with the onset of intensive N uptake at shooting. Ammonium concentrations in the suction solution were very low (0-0.16 mg N l^?1). Compared to preplanting NCyN application, preplanting NH₄-N and split NO₃-N application decreased nitrate concentrations in the suction solution in spring 1987. In 1988, however, nitrate concentrations in the suction solution of preplanting NH₄-N and split NO₃-N application plots did not fall below 50mgNl^?1 at 15 cm depth during the growing season. Nitrate concentrations of split NO₃-N application increased again in autumn 1988 and hence doubled the calculated N losses by leaching during the winter months compared to preplanting N applications. At shooting, plants of the preplanting NH₄-N treatment had lower nitrate concentrations in leaf sheaths compared to plants of preplanting NO₃-N application. Total N uptake of maize between shooting and early grain filling of preplanting NH₄-N and split NO₃ -N application tended to be higher compared to preplanting NO₃-N application, reflecting the higher N availability in the soil later in the season. However, final dry matter yields and N uptake were not significantly affected by N form or time of N application. Since N losses by nitrate leaching between N application and onset of N uptake by plants were negligible on the experimental site, preplanting NH₄-N application and split NO₃-N application showed no agronomic advantages. High amounts of side dressed NO₃-N may increase nitrate leaching during the winter months, especially in years with delayed rainfall after application.     

A Prominent Role for Leaf Calcium as a Yield and Quality Determinant in Upland Cotton (Gossypium hirsutum L.) Varieties Grown Under Irrigated Mediterranean Conditions

Seven cotton (Gossypium hirsutum L.) accessions were tested over 2 years under irrigated Mediterranean conditions on a loamy soil with nitrogen (N) as the only nutrient input. The study aimed to identify the critical nutritional and physiological factors determining seedcotton yield and fibre quality. A suite of leaf physiological traits [chlorophyll content (assessed by SPAD), carbon isotope discrimination (Δ), ¹⁵N natural abundance (δ¹⁵N), leaf water potential, N and C concentrations, C/N ratio, K, Na, Ca and Mg concentrations, their sum and ratios] was assessed, and their interrelationships then analysed. It was found that physiological indices such as SPAD, Δ and δ¹⁵N failed to discern genotypes for yield and did not relate with fibre quality traits. At the same time, leaf Ca concentration was the trait that showed the strongest correlation with both seedcotton (SY) and lint yield (LY). An increase of K/Na ratio up to 5.74 was beneficial for SY but higher ratios impacted yield adversely. In this line, exclusion of K in favour of Ca (lower K/Ca ratios) increased both SY and LY. The above results could be explained by Ca²⁺ control over activity of tonoplast and plasma membrane cation channels, resulting in redistribution of K⁺ between cell compartments. It is suggested that Ca²⁺‐rich plants are more efficient in sequestering higher K⁺ quantities in leaf vacuoles, at the expense of cytosolic K⁺. Under K⁺‐limiting conditions, such redistribution may trigger programmed cell death and enhance leaf senescence. This would remobilize and translocate nutrients (e.g. N) and organic substances to sinks (seedcotton), contributing to higher yields reported in the present work.