不同品种水稻对砷的吸收转运及其健康风险研究

为了比较不同品种水稻砷的积累特点,筛选可食用部分低砷积累水稻品种,研究通过盆栽试验,分析了江苏省常见的11个水稻品种根、茎、叶、谷壳和籽粒中的砷含量、砷的转运系数和根表铁膜厚度及其对砷固持的影响,并预估了不同品种水稻籽粒砷的健康风险。结果表明,不同品种水稻各部位的砷含量差异显著(P <0.05),泰瑞丰5号籽粒中的砷含量最高,而镇稻16号籽粒中的砷含量最低,后者大约是前者的一半。砷在水稻相邻部位的转运系数存在品种间差异(P <0.05),砷在水稻叶与籽粒间的转运系数最大的水稻品种是泰瑞丰5号,最小的是镇稻16号。根表铁膜量在不同品种间差异显著(P <0.05),其中淮稻6号的铁膜量是武运粳23的2.17倍。根表铁膜量与铁膜中的砷含量及水稻根叶中的砷含量均呈显著正相关关系(P <0.05)。不同水稻品种间的目标风险指数(THQ)也存在显著差异,其中泰瑞丰5号的THQ值最高,而镇稻16号的THQ值最低,两者相差0.99倍。研究表明,镇稻16号由于较低的砷吸收和转运能力,在中低砷污染土壤上种植风险较小,而泰瑞丰5号风险最大。     

氮肥类型对不同稻作模式水稻生长和产量的影响

探究复合肥、缓/控施肥、有机无机互混肥和不施氮肥对传统中稻模式和稻虾共生模式下水稻生长动态及产量的影响,为不同稻作模式下优化氮肥管理和提高水稻产量提供理论依据。采用裂区设计,2种稻作模式为主区,4种氮肥施用类型为裂区,于水稻主要生育期内调查水稻叶面积指数(LAI)和光合势(LAD)、干物质积累量(DW)和生长速率、光合特征,成熟后测定产量及产量构成因子,计算收获指数和氮肥偏生产力。结果表明:稻虾共生模式下水稻生育期延长,抽穗期LAI、抽穗期和成熟期DW、生长速率、抽穗期SPAD值和净光合速率、产量显著降低,抽穗期至成熟期LAD显著增加。常规中稻模式下未施氮处理的生殖生长期和全生育期短于3个施氮处理,稻虾共生模式下未施氮处理的营养生长期和全生育期长于3个施氮处理。有机无机互混肥的各时期LAI、LAD、抽穗期光合能力和千粒重最高,复合肥的分蘖期光合能力和抽穗期至成熟期生长速率最高,缓/控释肥的各时期DW、分蘖期至抽穗期生长速率、有效穗数、产量和氮肥偏生产力最高。缓/控释肥是两种稻作模式下水稻产量和氮肥偏生产力最高的最佳氮肥类型。     

不同品种水稻的产量构成因素及其对氮磷吸收的差异研究

为筛选出适合江苏地区种植的高产、高效水稻品种,采用盆栽试验,测定了江苏地区常见的11个水稻品种的株高、产量、结实率、总干物质量以及不同部位N、P含量,分析了水稻产量与其构成因素、氮磷积累量、氮磷收获指数间的相关关系。结果表明,水稻平均产量为16.85 g pot~(-1),变化幅度为8.28~25.18 g pot~(-1),品种间产量差异显著(P0.05),其中泰瑞丰5产量最高。水稻各部位氮素含量从大到小依次为:籽粒叶≈根茎谷壳,其中苏秀9籽粒中氮含量显著高于其他品种。磷素在水稻各部位中的含量分布为:籽粒根≈茎叶≈谷壳,籽粒中的磷含量最多的是南粳5055。相关分析表明,水稻的产量与总干物质量、穗粒数、氮磷积累量及氮磷收获指数均存在显著的相关性。不同品种水稻的产量、籽粒氮磷含量存在显著差异,这为高产、高效水稻品种的筛选提供了重要的科学依据。     

不同生育阶段洪涝淹没时长对水稻生长发育及产量构成的影响

夏季小流域洪涝常常导致南方稻田受淹并成灾。为探究小流域洪涝淹没时长对水稻生长发育及产量的影响,于2015—2016年在广西象州县选用丝香1号和百香139进行双季稻淹水试验,分别设分蘖期、孕穗期和开花期淹没0(对照CK)、2、4、6、8、10 d处理,测定淹没前后的茎蘖数变化、抽穗期及收获后的每穗粒数、结实率、千粒质量和每盆稻谷产量,并对产量构成因素进行相关分析和通径分析。结果表明:与对照组相比,同一生育期内淹没时间越长茎蘖死亡率越高、植株恢复生长越慢,但不同的淹没时期影响程度和主要影响对象存在差异。分蘖期淹没超过6d则死苗率大于80%,且不能完全恢复生长,收获时水稻茎蘖数显著低于对照组;孕穗期淹没超过6d则死苗率大于50%,而淹没小于4 d的处理水稻能恢复生长,收获时水稻茎蘖高于对照组;开花期淹没10 d死苗率不足50%,收获时茎蘖数与对照组差异不显著。分蘖期淹没小于4 d水稻始穗期及抽穗持续时间均无显著变化,大于8 d则水稻始穗期显著推迟,抽穗持续时间增加;孕穗期受淹没则会使水稻始穗期推迟,抽穗持续时间显著增加,甚至收割时也未能达到齐穗期标准。分蘖期淹没小于4 d,单株产量无显著下降,淹没6 d及以上则减产率大于80%;孕穗期及开花期淹没超过2 d则减产率大于50%。不同生育期淹没处理下产量的主要因素不同,分蘖期主要受有效穗数和结实率影响,孕穗期受结实率及每穗粒数影响,开花期受结实率和有效穗数影响。研究可为建立西南地区双季稻洪涝灾害指标体系和提出减灾管理措施提供依据。     

夜间增温对小麦干物质积累、转运、分配及产量的影响

为明确夜间增温对小麦产量形成的影响,于2019—2020和2020—2021年两个小麦生长季,以苏麦188和安农0711为试验材料,采用被动式夜间增温方法,以不增温为对照,对小麦生育前期3个阶段(分蘖期至拔节期、拔节期至孕穗期、孕穗期至开花期)进行夜间增温处理,研究不同阶段夜间增温处理对小麦干物质积累、分配、转运以及产量的影响。结果表明,分蘖期至拔节期与拔节期至孕穗期夜间增温处理均能提高小麦孕穗期和开花期的旗叶叶面积,且分蘖期至拔节期夜间增温处理与对照差异显著,孕穗期至开花期夜间增温处理的旗叶叶面积较对照有所降低;在小麦拔节期和孕穗期时,分蘖期至拔节期与拔节期至孕穗期夜间增温处理较对照均提高了小麦的株高,开花期各增温处理的株高与对照无显著差异;分蘖期至拔节期与拔节期至孕穗期夜间增温处理均提高了小麦干物质的积累量和产量,在分蘖期至拔节期夜间增温处理下,苏麦188和安农0711的两年平均产量较对照分别提高了5.63%和6.77%。综上,分蘖期至拔节期夜间增温处理提高了小麦的叶面积和株高,使其获得更多的光能用于光合作用,最终增加了小麦的干物质积累量和产量。本研究结果为制定未来气候变化背景下的农业适应战略提供了理论依据。     

孕穗-灌浆期低温对三江平原主栽水稻品种品质的影响

以三江平原主栽水稻品种龙粳29、龙粳31和龙粳46为材料,在水稻孕穗期、抽穗期和灌浆期利用人工气候箱以日平均气温16℃低温水平,对盆栽水稻处理5d,以正常栽培管理的试验材料为对照,分析不同发育时期,低温胁迫对3个水稻主栽品种产量构成因素、碾磨品质、营养品质和RVA谱特征参数的影响。结果表明:孕穗期、抽穗期和灌浆期低温处理后水稻的结实率、千粒重、糙米率、精米率、整精米率以及食味评分均降低,且与对照相比呈显著差异(P0.05);低温处理后稻米蛋白质含量显著升高,直链淀粉含量在孕穗期和抽穗期显著降低,灌浆期逐渐增加,灌浆末期高于对照;RVA谱特征参数因品种差异与对照相比有增有减,但均呈显著性差异(P0.05)。孕穗期低温胁迫对水稻产量、研磨品质和营养品质影响最大,灌浆期低温胁迫对水稻RVA谱特征参数影响最大,且3个品种间存在明显差异(P0.05)。低温胁迫下龙粳46的产量构成因素与对照相比,除孕穗期千粒重外其余差异均不显著,表现出较强的耐冷性,龙粳29研磨品质和营养品质,龙粳46的RVA谱特征参数受低温影响最小。三江平原水稻生产栽培、抗性育种和气候品质认证要综合考虑主栽品种的品质指标,在孕穗-灌浆期采取相应的米质调优栽培措施,根据气候变化科学客观地对稻米进行气候品质认证。     

不同施氮水平下水稻的养分吸收、转运及土壤氮素平衡

【目的】为解决东北地区水稻合理施用氮肥问题,系统研究了不同施氮水平条件下,东北水稻产量及构成因素、养分吸收、转运、氮肥利用效率及土壤氮素平衡的变化,并探讨各养分间及其与产量间的关系,为东北地区水稻合理施氮提供理论基础。【方法】于2012~2013年在吉林省松原市前郭县红光农场,选用当地主栽水稻品种富优135和吉粳511为材料,设置施N 0、60、120、180和240 kg/hm25个水平。于水稻返青期、分蘖期、抽穗期、灌浆期及成熟期采集植株样本,分为茎鞘、叶片和籽粒三部分,测定氮、磷、钾含量,计算水稻主要生育期植株养分吸收、转运、氮素利用特性的相关参数及各养分吸收、转运与产量间的关系。水稻移栽前和收获后采集0—100 cm土壤样品,每20 cm为一层(共5层),测定铵态氮、硝态氮含量,并根据各层土壤容重计算0—100 cm土体无机氮积累量,分析土壤氮素平衡状况。【结果】施氮量60~180 kg/hm2范围内,水稻产量随着施氮水平的提高而增加,氮肥用量超过180 kg/hm2水稻产量下降。结合当年水稻和肥料价格,根据水稻产量(y)和施氮量(x)拟合方程,得出最高产量氮肥用量分别为212.8 kg/hm2和220.6 kg/hm2,施氮范围在202.2~231.6 kg/hm2之间,最佳经济产量氮肥用量分别为203.0和209.1 kg/hm2,施氮范围在192.9~219.6 kg/hm2之间。施用氮肥可显著提高水稻主要生育期氮、磷、钾吸收量,且能提高水稻抽穗期氮、磷、钾养分向籽粒的转运,施氮量180 kg/hm2处理抽穗期各养分累积量与籽粒转运量呈正比,当氮肥用量超过180 kg/hm2后,氮、磷、钾养分向籽粒转运出现负效应。氮素农学利用率和偏生产力随着施氮水平的提高而显著下降,氮肥当季回收率以施氮量180 kg/hm2处理最高。相关分析表明,水稻主要生育期氮、磷、钾的吸收、转运与产量间均存在显著或极显著的正相关性,其中灌浆期氮、磷、钾的吸收状况与产量间的相关系数最大。施用氮肥可显著提高收获后0—100 cm土壤中残留无机氮(Nmin),氮素表观损失量随施氮水平的提高而增加。【结论】适宜的氮肥用量可显著提高水稻产量,各生育时期养分吸收总量,提高水稻生育后期秸秆中氮、磷、钾向籽粒的转运量,并能降低土壤氮素表观损失量。综合考虑提高水稻产量、效益、氮肥当季回收率及维持土壤氮素平衡等因素,在本试验条件下,施氮范围在192.9~219.6 kg/hm2。     

不同产量水平下稻茬小麦的氮素营养指标特征

  【目的】  明确长江中下游地区不同产量水平稻茬小麦氮营养指标变化规律,为小麦氮素营养状况实时诊断提供理论依据。  【方法】  本研究通过江苏省多年多点田间不同氮肥、播期、密度和品种试验,构建不同产量水平小麦大数据,分析不同产量水平小麦在不同生育时期的干物质积累量、植株氮积累量和植株氮浓度的变化规律,并通过计算小麦临界氮浓度,得到累积氮亏缺和氮营养指数的动态变化规律,进而明确高产稻茬小麦氮素营养指标特征。  【结果】  干物质积累量和植株氮积累量的变化趋势一致,随着小麦生育进程的推进均逐渐增加,植株氮浓度逐渐减小,累积氮亏缺和氮营养指数会出现波动。整个生育期内,干物质积累量和植株氮积累量在高产小麦和中产小麦之间的差异不显著,但二者植株氮积累量均显著高于中低产小麦,中低产小麦又显著高于低产小麦。在抽穗期、开花期和灌浆期,高产和中产小麦干物质积累量显著高于中低产小麦,中低产小麦又显著高于低产小麦。依据累积氮亏缺值判断氮素营养状况,高产和中产小麦的累积氮亏缺变化趋势一致,在起身—孕穗期,高产小麦的累积氮亏缺值由0.3 kg/hm2降低为?23.0 kg/hm2,中产小麦由7.0 kg/hm2降低为?14.6 kg/hm2,孕穗—抽穗期又呈升高趋势,高产小麦由?23.0 kg/hm2升高为?11.4 kg/hm2,中产小麦由?14.6 kg/hm2升高为2.4 kg/hm2,开花—灌浆期的波动较小。表明高产小麦氮营养除起身期之外均为过剩,中产小麦在拔节—孕穗期的累积氮亏缺小于0,其余时期累积氮亏缺均大于0,但该水平的累积氮亏缺值一直在适宜范围内波动。中低产小麦在起身—拔节期,累积氮亏缺值由14.2 kg/hm2降低为9.5 kg/hm2,之后逐渐升高,灌浆期达到最大为43.9 kg/hm2;低产小麦在起身期到灌浆期,累积氮亏缺值由17.3 kg/hm2升高为71.1 kg/hm2。表明中低产和低产的小麦氮营养水平在整个生育期内逐渐降低,且整个生育期均处于亏缺状态 (累积氮亏缺值 > 0)。在拔节期、孕穗期、抽穗期和灌浆期,高产水平的小麦植株实际氮浓度高于植株临界氮浓度,中产小麦在孕穗期的植株实际氮浓度高于临界氮浓度,而中低产和低产的小麦在整个生育期植株实际氮浓度低于植株临界氮浓度。高产和中产的小麦氮营养指数在1附近波动,其中高产小麦的氮营养指数在起身—孕穗期由0.9升高为1.1,在抽穗—灌浆期,氮营养指数呈现先降低后升高趋势,其值分别为1.0、0.9和1.0,中产小麦与高产小麦的变化趋势一致,起身—孕穗期的氮营养指数由0.8升高为1.0,之后逐渐下降,其值均小于1,抽穗—灌浆期分别为0.9、0.9和0.9。中低产和低产的小麦氮营养指数始终低于1,中低产小麦在起身—拔节期氮营养指数由0.7升高为0.8,之后则逐渐下降,低产小麦从起身—开花期均逐渐下降,而这两个产量水平的氮营养指数在灌浆期会呈现略微上升趋势。  【结论】  随着产量水平的提高,小麦植株干物质和氮积累量、植株氮浓度、氮营养指数等都相应增加,累积氮亏缺相应下降。较高的干物质积累量和植株氮积累量是提高小麦产量的主要原因,在小麦生长过程中氮营养指数和累积氮亏缺均能准确诊断小麦氮营养状况,可为小麦氮肥精准管理提供理论支持。     

夜间增温对水稻生长、生理特性及产量构成的影响

2015年6-11月,在大田条件下采用铝箔反光膜覆盖对水稻(南粳46)进行夜间增温试验。试验设置夜间增温(NW)和对照(CK)两个处理,在水稻主要生育期(分蘖期、拔节期、抽穗扬花期、灌浆期和成熟期)观测水稻分蘖数、叶绿素含量(SPAD值)、叶面积指数、光合作用和蒸腾作用参数以及产量构成(有效穗数、穗粒数和千粒重)。结果表明:(1)铝箔反光膜覆盖达到了夜间增温的目的,整个生育期夜间水稻冠层平均气温比对照提高0.4℃。(2)夜间增温条件下,水稻分蘖数比对照平均每株减少4.33个;各生育期叶片叶绿素含量(SPAD值)分别下降0.2%、2.75%、6.31%、10.77%和32.03%,而叶面积指数差异不大。(3)NW处理各生育期水稻叶片的光合和蒸腾作用参数,包括净光合速率、气孔导度和蒸腾速率均显著低于对照(P0.05)。(4)NW处理每穗粒数和有效穗数分别比对照低12.76%和19.02%,产量下降32.54%,千粒重增加3.93%。研究认为,夜间增温对水稻的生长及光合作用产生显著影响,在未来气候变化背景下,应进一步研究不同增温方式对水稻生产的影响及其模型模拟。     

豫南紫云英水稻轮作区减施不同比例氮肥对水稻养分吸收和转运的影响

  【目的】  研究水稻–紫云英轮作体系中,翻压紫云英并减施氮肥对不同生育期水稻养分吸收、转运特征,以及对土壤养分状况的影响,为豫南稻区紫云英–水稻轮作模式氮肥的科学管理提供理论依据。  【方法】  长期定位试验位于河南信阳,始于2008年。试验设置不施肥对照(CK)、常规施肥(N100),以及种植并翻压紫云英条件下,氮肥为常规处理用量的100% (GN100)、80% (GN80)、60% (GN60)、40% (GN40),共6个处理。测定了水稻产量、关键生育期生物量、氮磷钾养分吸收量、土壤基础养分含量,分析了水稻养分吸收及土壤养分供应对水稻产量的影响。  【结果】  与N100处理相比,GN40、GN60、GN80和GN100处理水稻产量无显著差异,GN40和GN60处理氮肥农学效率分别增加213.41%和113.70%,GN40、GN60和GN80处理氮肥偏生产力分别增加162.17%、75.69%、34.39%。与N100处理相比,GN100和GN80处理抽穗期秸秆生物量分别增加17.22%和41.06%,成熟期秸秆生物量分别增加28.22%和20.92%。与N100处理相比,GN60、GN80和GN100处理成熟期稻谷氮吸收量分别增加31.34%、31.79%和20.13%,GN60、GN80成熟期稻谷磷吸收量分别增加14.23%和14.61%,GN80处理成熟期稻谷钾吸收量增加10.64%。与N100处理相比,GN60处理氮转运量增加12.54 kg/hm2;GN40、GN60和GN80处理磷转运量分别显著增加11.32、23.02和18.09 kg/hm2,磷转运率分别增加35.92、41.22和39.91个百分点,磷对稻谷转运贡献率分别增加39.36、74.60和57.93个百分点。与N100处理相比,GN40、GN60、GN80和GN100能充分满足水稻生长过程中对土壤无机氮需求;GN60、GN80处理分蘖期、拔节期和抽穗期土壤有效磷含量显著降低;GN40、GN60、GN80和GN100处理分蘖期、抽穗期和成熟期土壤速效钾含量显著降低。随机森林分析结果表明各生育期土壤有效磷含量和水稻分蘖期氮、磷、钾吸收量对水稻产量形成有较大的贡献。线性回归分析表明,分蘖期和抽穗期土壤养分含量以及各生育期地上部氮、磷、钾吸收量与稻谷产量呈显著正相关。  【结论】  在我国豫南紫云英–水稻轮作区,翻压紫云英配合氮肥减施40%,能够培育土壤碳、氮库,满足土壤氮素供应,促进水稻对磷、钾养分的吸收和积累,增加籽粒氮、磷、钾养分转运量,提高氮肥农学效率和偏生产力,实现水稻增产稳产。     

Growth,yield and yield components of dry bean as influenced by phosphorus in a tropical acid soil

Phosphorus (P) deficiency is one of the most yield limiting factors for dry bean (Phaseolus vulgaris) production in tropical acid soils. Dry beans are invariably grown as mono-crops or as inter-crops under the perennial tropical crops. Information is limited regarding the influence of phosphorus fertilization on dry bean yield and yield components and P use efficiency in tropical acid soils. A greenhouse experiment was conducted to evaluate the influence of phosphorus fertilization on dry bean growth, yield and yield components and P uptake parameters. Phosphorus rates used were 0, 50, 100, 150, 200, and 250 mg P kg^?1 of soil. Soil used in the experiment was an acidic Inceptisol. Grain yield, shoot dry weight, number of pods, and 100 grain weight were significantly (P < 0.01) increased with phosphorus fertilization. Maximum grain yield, shoot dry matter, number of pods, and 100 grain weight were obtained with the application of 165, 216, 162, and 160 mg P kg^?1 of soil, respectively, as calculated by regression equations. Grain yield was significantly and positively associated with shoot dry weight, number of pods, P concentration in grain and total uptake of P in shoot and grain. Phosphorus use efficiency defined in several ways, decreased with increasing P rates from 50 to 250 mg P kg^?1 of soil. Maximum grain yield was obtained at 82 mg kg^?1 of Mehlich 1 extractable soil P. Results suggest that dry bean yield in Brazilian Inceptisols could be significantly increased with the use of adequate rates of phosphorus fertilization.     

Relationships among important traits in the nitrogen economy of winter wheat

Identification and utilization of important attributes in the nitrogen economy of wheat (Triticum aestivum L.) should provide a basis for increasing grain protein percentage (GPP). The objectives of this study were to determine the magnitude of genetic variability of some factors important in the nitrogen economy of wheat, their relationship to one another, and their influence on grain yield (GY) and GPP. Twenty‐five hard red winter wheat genotypes representing a wide range of GY, GPP, and plant stature were grown in field trials over a 2‐year period. Significant differences were found for harvest index (HI) and nitrogen harvest index (NHI). Total nitrogen at anthesis (TNA), total nitrogen at maturity (TNM), and biological yield (BY) did not differ significantly. GPP was positively correlated with TNM and BY and negatively correlated with TNA, HI, and GY. GPP was not correlated with NHI, however, stepwise regression of GPP and grain protein yield revealed NHI as a common component, with a positive coefficient. In addition, NHI was positively correlated with GY. Selection of parents with complementary traits for nitrogen‐use efficiency may allow for simultaneous increases in GY and GPP.     

Nitrogen relations in winter wheat cultivars differing in grain protein percentage and stature

Accumulation of reduced nitrogen and its partitioning between vegetative tissue and grain are two important aspects of the nitrogen economy of wheat (Triticum aestivum L.). The objectives of this study were to 1) determine the range of nitrogen harvest index (NHI) among four hard red winter wheat cultivars differing in grain protein percent (GPP) and the influence of NHI on grain protein percent, and 2) to contrast the partitioning of nitrogen and dry matter to the component parts of the plant throughout growth and development. Plants were grown in a nutrient solution and nitrogen salts were withheld from the solution when the wheat reached anthesis. High nitrogen percentage of plant parts tended to correlate positively with grain protein percentage at first node and anthesis stages, but correlated negatively at latter stages. Dry weight was important in the accumulation of nitrogen; however, neither dry weight nor total plant nitrogen was correlated with GPP. Nitrogen harvest index was correlated strongly and positively with GPP and was independent of plant stature. The selection of parents with high NHI could be an important criterion in breeding programs to increase GPP of wheat.     

Dry matter and primary nutrient accumulation in soybeans as affected by combined Nitrogen levels

Nodulating and non‐nodulating soybeans were grown on a Alfic Udipsamment and a Typic Hapludoll amended with 10 or 100 kg N/ha. Tissue and grain samples were analyzed to determine N₂‐fixation, dry matter, and N, P, and K accumulation. Highest grain yields were associated with the highest levels of N₂‐fixation and N and K accumulation in grain. The largest dry matter production was by nodulating plants grown on a high soil N regime. Nodulating plants accumulated more grain and tissue N, P, and K than non‐nodulating plants. Nitrogen stress increased P concentrations in both grain and tissue and decreased harvest indices.     

温室黄瓜干物质分配与产量预测模拟模型初步研究

依据温室黄瓜(Cucumis sativus)器官生长与温度和辐射的关系，建立了基于分配指数和采收指数的温室黄瓜干物质分配与产量预测模拟模型，并利用不同品种和基质的试验资料对模型进行了检验。结果表明，模型对黄瓜地上部分干重、根干重、茎干重、叶干重、果实干重的预测结果与1∶1直线之间的R²分别为0.98，0.73，0.83，0.92，0.94；RMSE分别为232，6.8，157.6，173.9，196.8 kg/hm²。模型对黄瓜产量的预测结果与1∶1直线之间的R²为0.80，RMSE为7526.4 kg/hm²。本模型对不同基质、品种的黄瓜干物质分配和产量的预测值与实测值符合度均较高，说明本模型的普适性较好。模型不仅能较好地预测中国现有生产水平下温室黄瓜的干物质分配及产量，而且可以为实现中国温室黄瓜生产环境优化调控和模式化栽培管理提供决策支持。     

Genotypic variation in partitioning of phosphorus in relation to nitrogen and dry matter during wheat grain development

Phosphorus has many similarities to N for plant nutrition, but little is known regarding P partitioning among genotypes and factors that affect it. Experiments were conducted to measure variation in partitioning of P and its relationship to N, dry matter, and yield components of wheat (Triticum aestivum L.). Sixteen cultivars grown under field conditions were sampled at anthesis for P, N, and dry matter and at maturity for the same constituents and for yield components. Relationships among the traits were determined by Spearman rank correlation coefficients. Accumulation of P and dry matter during grain development and grain HI, NHI, and PHI differed significantly among genotypes. Post‐anthesis P, N, and dry matter accumulation correlated positively as did HI, NHI, and PHI, but accumulation of the constituents was not related to their His. The positive associations were attributed to requirement of P and N for growth and their accumulation as reserve compounds in grain. Genotypic variation in PHI may be as useful as variation in HI and NHI for wheat improvement.     

Potassium-Use Efficiency in Upland Rice Genotypes

Potassium (K) uptake is greatest among essential nutrients for rice. Data related to yield, yield components, and K-use efficiency by upland rice genotypes are limited. A greenhouse experiment was conducted to evaluate influence of K on growth, yield and yield components, and K-use efficiency by upland rice genotypes. Potassium levels applied to an Oxisol were zero (natural K level) and 200 mg K kg¹ of soil and 20 upland rice genotypes were evaluated. Plant height, shoot dry weight, grain yield, 1000-grain weight, and spikelet sterility were significantly affected by K and genotype treatments. Genotypes Primavera and BRA 1600 were the most efficient and genotype BRAMG Curinga was most inefficient in producing grain yield. Plant growth (plant height and shoot dry weight) and yield components (panicle number, grain harvest index, 1000-grain weight, and panicle length) were significantly and positively associated with grain yield. However, spikelet sterility was significantly and negatively correlated with grain yield.     

Nutrient uptake,partitioning, and removal in two modern high-yielding Colombian rice genotypes

Abstract

The objective of this research was to determine the difference on growth between a rice cultivar with Clearfield^® technology (Only Rice 228) and a hybrid (Benja 1); to characterize nutrient uptake, distribution, accumulation and removal between these two commercial genotypes. Tests under shade house and field conditions were performed to estimate macro and micronutrient uptake patterns. Plants were sampled at nine growth stages (emergence, initiation of tillering, active tillering, initiation of panicle primordia, booting, flowering, milky, soft dough and mature grain) and divided into different organs for nutrient determination. The results showed that “Benja 1” plants (92 d) had a shorter cycle than “Only Rice 228” (OR 228) plants (118 d). “OR 228” exhibited a greater biomass production (16.575?kg ha^?1 vs. 12.621?kg ha^?1) in field. The nutrient acquisition was faster in the hybrid Benja 1 between tillering initiation and the milky grain stage in which the N, K, Ca, Mg, Mn, B, and Cu uptake was more evenly and highly distributed throughout these stages in both conditions. “Benja 1” showed a higher nutrient harvest index (HI). HI values above 50% (P (62%), N (61%), Cu (67%), S (55%), and Mg (52%)) were found in Benja 1 under field conditions. The results also highlight Si removal in both rice genotypes, in which Benja 1 stands out. These results provide information on the nutrient uptake and partitioning of modern rice genotypes, and give the knowledge to optimize fertilizer programs and timing recommendations for rice biomass and grain production in Colombia.     

DRY BEAN GENOTYPES EVALUATION FOR GROWTH,YIELD COMPONENTS AND PHOSPHORUS USE EFFICIENCY

Dry bean along with rice is a staple food for the population of South America. In this tropical region beans are grown on Oxisols and phosphorus (P) is one of the most yield limiting factors for dry bean production on these soils. A greenhouse experiment was conducted to evaluate P use efficiency in 20 elite dry bean genotypes grown at deficient (25 mg P kg^?1 soil) and sufficient (200 mg P kg^?1) levels of soil P. Grain yields and yield components were significantly increased with P fertilization and, interspecific genotype differences were observed for yield and yield components. The grain yield efficiency index (GYEI) was having highly significant quadratic association with grain yield. Based on GYEI most P use efficient genotypes were CNFP 8000, CNFP 10035, CNFP10104, CNFC 10410, CNFC 9461, CNFC 10467, CNFP 10109 and CNFP 10076 and most inefficient genotypes were CNFC 10438, CNFP 10120, CNFP 10103, and CNFC 10444. Shoot dry weight, number of pods per plant, 100-grain weights and number of seeds per pod was having significant positive association with grain yield. Hence, grain yield of dry bean can be improved with the improvement of these plant traits by adopting appropriate management practices. Soil pH, extractable P and calcium (Ca) saturation were significantly influenced by P treatments. Based on regression equation, optimum pH value in water was 6.6, optimum P in Mehlich 1 extraction solution was 36 mg kg^?1 and optimum Ca saturation value was 37% for dry maximum bean yield.     

Potassium requirement in relation to grain yield and genotypic improvement of irrigated lowland rice in China

The yield of rice (Oryza sativa L.) has increased substantially with the development of new cultivars, but the role of potassium (K) requirement for the increase in grain yield and the genotypic advance is still unclear. In order to investigate this relationship a database of 1199 on‐farm measurements (harvest index 0.4) comprising > 400 modern rice cultivars was collected during 2005–2010 across major irrigated lowland rice–production regions of China. This was used to evaluate the relationships among K requirement, grain yield, and genetic improvement. Across all the sites and seasons, mean reciprocal internal efficiency of K (RIE‐K, kg K [t grain produced]^–1) was 19.8 kg K (t grain)^–1 and rice yield averaged 8.7 t ha^–1. Considering four levels of grain yield (< 7.5, 7.5–9, 9–10.5, and > 10.5 t ha^–1), the respective RIEs were 18.7, 19.4, 20.5, and 21.7 kg K (t grain)^–1. The gradual increase in the RIE‐K with yield was attributed mainly to the increase in straw and grain K concentration and the decrease in the K harvest index. The RIE‐K values for ordinary inbred, ordinary hybrid, and “super rice” were 18.5, 20.1, and 19.9 kg K (t grain)^–1, respectively. Examining the historical development of rice cultivars, the RIE‐K decreased from 40.9 (Nanjing1, early tall, inbred) in the 1950s to 19.8 (IR24, semi‐dwarf, ordinary inbred) in the 1970s, and then increased to 20.9 (Shanyou63, modern ordinary hybrid) in the 1980s and 20.6 kg K (t grain)^–1 (II‐you084, “super” rice) in the 2000s. This variation in RIE‐K among grain‐yield levels and cultivars highlights the importance of information on rice K requirement in calculating K balance and optimal K‐fertilizer rate for rice production.