不同生育期小麦冠层SPAD值无人机多光谱遥感估算

随着长江中下游稻麦轮作区水稻成熟期的推迟,冬小麦播期的推迟已经成为影响产量的主要障碍,因此在迟播小麦中筛选抗性较好的品种很有必要。该研究旨在监测冬小麦生长早期冠层叶片的相对叶绿素含量,用于迟播冬小麦品种筛选。为探讨利用无人机多光谱影像监测冬小麦叶绿素含量的可行性,基于多光谱无人机获取的5个单波段光谱反射率和15个植被指数作为自变量,经过递归特征消除法(RFE)特征变量筛选,去除冗余变量,利用后向神经网络(BP)回归算法构建冬小麦相对叶绿素含量(SPAD)值遥感反演模型。根据2020年—2021年江苏省扬州市广陵区实验点冬小麦越冬期、拔节期两个生育期的实测叶片SPAD值,结合同步获取的多光谱无人机影像,分析了这两个生育期遥感变量和SPAD值之间的相关性。并结合遥感变量之间的特征重要性排序进行特征变量筛选,筛选出的变量作为模型的输入,构建并筛选出各生育期最佳的反演模型。比较岭回归(Ridge)和梯度提升树(GBD)算法,以R^(2)和RMSE作为模型评价指标,在验证集上分析了各生育期3种模型的自学习能力和泛化能力。结果表明,经过了最优光谱信息筛选而建立的BP神经网络模型在此两个生育期的数据集上均表现出了最强的回归预测能力。R^(2)和RMSE在越冬期分别为0.806和1.861,拔节期分别为0.827和0.507。通过对无人机多光谱数据进行变量筛选,构建的优选模型BP神经网络具有较高估算精度,且表明在冬小麦的早期监测中,拔节期比越冬期效果好。利用无人机多光谱在估算迟播冬小麦SPAD值进行品种抗性筛选的方法是有价值的。

侧深施肥下水稻高产形成的根系形态及其生理变化特征

水稻侧深施肥是均匀地将肥料深施在秧苗一侧土壤根际的一种不对称局部施肥技术,具有减肥增产、提高肥料利用率和减少劳动力投入等优点,然而侧深施肥下水稻根系特征及其与产量形成的关系尚不清楚。本试验以丰粳1606和南粳9108为材料,设置普通尿素常规施肥(conventional fertilization with common urea,CF)、缓释肥减氮15%表施(conventional fertilization with 15%reduction of control released fertilizer,CFCR)、普通尿素减氮15%侧深施肥(side-deep fertilization with 15%reduction of commonurea,SDCU)和缓释肥减氮15%侧深施肥(side-deepfertilization with 15%reduction of control released fertilizer,SDCR)4种氮处理,研究不同施肥方式对水稻根系形态结构和生理特征以及产量的影响。结果表明:(1)SDCR处理水稻产量最高,其次分别为CF和CFCR处理,而SDCU处理产量最低;(2)SDCR处理显著提高了不同生育时期总根长、根尖数、根表面积和根体积;(3)SDCR处理降低了不同生育时期根系的皮层横截面积、皮层细胞层数和不定根直径,提高了根系中柱直径,但对皮层生活细胞面积和通气组织面积影响不显著;(4)与CF处理相比,SDCR处理显著提高了根系活力;根系氮代谢酶在生育期内呈现先上升后下降趋势,抽穗期达到峰值,其中SDCR处理下不同生育时期水稻根系谷氨酸合成酶和谷氨酰胺合成酶活性最高。因此,缓释肥侧深施肥可改善根系形态、结构和生理特征,增强根系吸收养分和水分能力,防止后期植株早衰,从而提高水稻产量,达到提高肥料利用效率,实现减氮增产的目的。

双季晚稻不同类型品种产量与主要品质性状的差异

为明确江西双季晚稻条件下籼粳杂交稻、杂交粳稻、常规粳稻、杂交籼稻4种类型品种产量与一般品质的差异,为江西双季晚稻适宜品种的科学选用与初步区划提供依据与参考,在江西上高县(28°31′N,115°09′E)试验点进行,比较研究表明与杂交籼稻相比,常规粳稻、杂交粳稻和籼粳杂交稻加工品质、蒸煮食味品质有所改善,而外观品质与营养品质略逊。产量表现为籼粳杂交稻>杂交粳稻>常规粳稻>杂交籼稻。本研究认为上高地区"籼改粳"工程适宜种植的晚稻品种为籼粳杂交稻、杂交粳稻和常规粳稻。

粒叶比对优质粳稻稻米品质的影响

为阐明不同粒叶比水稻群体的稻米品质特征与差异,以大面积生产上代表性迟熟中粳水稻品种淮稻5号和南粳9108为试验材料,设置穗肥施氮量和齐穗期花叶疏剪处理,在灌浆结实期形成不同粒叶比差异的水稻群体,以研究粒叶比对优质粳稻稻米品质的影响。结果表明,随粒叶比的提高,稻米的糙米率、精米率和整精米率降低,稻米加工品质变差。高粒叶比处理的米粒垩白粒率和垩白度较高,外观品质较差;稻米蛋白质含量随粒叶比的升高而降低,水稻粒叶比低,则营养品质优。增加水稻粒叶比能降低直链淀粉含量,增加胶稠度、黏度和平衡度,降低硬度,提高米饭食味值。穗肥用氮量减少,稻米外观品质变优,米饭食味值提高,水稻淀粉黏滞性改善。在穗肥施氮量和齐穗期花叶疏剪处理下,稻米直链淀粉含量和蛋白质含量均与食味值呈极显著负相关关系,且蛋白质含量与食味值的相关性更大。因此,减施穗肥施氮量和提高粒叶比均利于米饭食味值增加,且蛋白质含量改变对米饭食味值的调节作用更大。

秸秆全量还田与氮肥运筹对机插粳稻产量及氮素吸收利用的影响

以常规粳稻南粳5055、南粳46为材料,在总施纯氮量为300 kg hm–2条件下,设置9∶1、8∶2、7∶3、6∶4、5∶5、4∶6共6种基蘖肥与穗肥比例,探讨秸秆全量还田条件下不同氮肥运筹对机插粳稻产量及氮素吸收利用特征的影响。结果表明,与秸秆不还田相比,秸秆全量还田具有显著的增产效应,南粳5055、南粳46平均增产5.04%、4.64%;随着基蘖氮肥占总施氮量比例的下降,秸秆全量还田机插粳稻产量呈先增后减的趋势,基蘖氮肥与穗氮肥比例为7∶3时,水稻产量最高。相同氮肥运筹模式下,秸秆全量还田处理水稻拔节期及移栽至拔节阶段的群体干物质积累量均低于秸秆不还田处理,抽穗期、成熟期及拔节至抽穗、抽穗至成熟阶段的群体干物质积累量则高于秸秆不还田处理。氮肥运筹间表现为随基蘖氮肥占总施氮量比例的下降,拔节期及移栽至拔节阶段的群体干物质积累量下降,而抽穗期、成熟期及拔节至抽穗、抽穗至成熟阶段的群体干物质积累量呈现先增后减的趋势。当基蘖氮肥与穗氮肥比例为7∶3时,秸秆全量还田条件下的水稻群体干物质积累量最高,经济系数也最高。秸秆全量还田水稻拔节前的氮素积累量低于秸秆不还田处理,拔节至抽穗、抽穗至成熟阶段的氮素积累量则高于秸秆不还田处理,秸秆全量还田处理的氮肥表观利用率、氮肥农学利用率和氮肥偏生产力均高于秸秆不还田处理。不同氮肥运筹间表现为随基蘖肥占总施氮量比例的下降,氮肥表观利用率、氮肥农学利用率、氮肥生理利用率及氮肥偏生产力均呈现先增后减的趋势,当基蘖氮肥与穗氮肥运筹比例为7∶3时最高。

秸秆还田条件下氮磷钾用量对软米粳稻产量和品质的影响

【目的】秸秆全量还田和毯苗机插技术在水稻种植中被越来越多地采用。本文研究了不同氮(N)、磷(P)、钾(K)肥用量对软米粳稻产量和稻米品质的影响,提出适应该条件和特定水稻品种的施肥技术。【方法】2014—2015年,以软米粳稻南粳9108为材料,在江苏省兴化市钓鱼镇进行大田试验,在秸秆全量还田条件下,采取毯苗机插栽培方式,设置氮、磷、钾肥3种类型肥料,各类型肥料设置0、1、1.5、2、2.5、3等6个用量水平,其中2水平为肥料常规用量,氮、磷、钾肥常规用量分别为270 kg/hm^2、108 kg/hm^2、216kg/hm^2。分析了不同肥料用量下软米粳稻的产量、稻米品质和淀粉RVA谱值。【结果】软米粳稻产量和稻米品质对不同肥料的响应程度表现为氮肥>钾肥>磷肥。在供试氮肥水平范围内,粳稻产量以N2水平最高;糙米率、精米率、整精米率和蛋白质含量则随施氮水平的增加而增加,直链淀粉含量降低,胶稠度变短,RVA谱特征值中峰值黏度和崩解值降低,热浆黏度和消减值增大,且高氮(N3)与低氮(N1)处理间差异显著。在供试磷肥水平范围内,粳稻产量以P2水平较高;增施磷肥能提高稻米加工品质,而蛋白质含量、直链淀粉含量及胶稠度对磷肥用量的响应无明显变化规律,淀粉RVA谱特征值有变劣趋势。在供试钾肥水平范围内,随着钾水平提高,机插软米粳稻产量、糙米率、精米率、整精米率先增加后减少,产量以K2水平最高,加工品质以K2.5水平最高,蛋白质含量有增加趋势,直链淀粉含量下降,峰值黏度和崩解值呈先增后减,消减值呈先减后增。【结论】在秸秆全量还田和毯苗机插栽培条件下,软米粳稻增施氮肥、磷肥和钾肥利于提高稻米加工品质,而减少氮肥、稳施磷肥、增加钾肥利于改善稻米蒸煮食味品质。综合考虑,在秸秆全量还田条件下机插软米粳稻肥料用量以N 270 kg/hm^2、P 108 kg/hm^2、K 216 kg/hm^2水平能较好地协调高产与优质的关系。

灌浆结实期低温弱光复合胁迫对稻米品质的影响

近年来,南方水稻抽穗灌浆期低温寡照天气发生频率明显增加,为探明其对稻米品质的影响,在水稻灌浆结实期不同时间段(1~7d、8~14d、15~21d、22~28d、29~35d)设置低温弱光复合胁迫(LW)、单一弱光(WN)、单一低温处理(LN)和常温常光(NN)4个处理,研究低温弱光复合胁迫对稻米加工品质、外观品质、蒸煮食味品质、RVA谱特征值等的影响。结果表明,不同处理方式间的垩白米率、垩白大小和垩白度均表现为LW>LN>WN>NN,且灌浆结实期各阶段的复合胁迫均较对照NN差异极显著或显著,除了2016年灌浆结实1~7d的垩白度外,灌浆结实21d内的复合胁迫与单一弱光、低温差异也显著或极显著,单一胁迫低温、弱光在灌浆结实21d内较对照NN差异极显著或显著,其中单一低温与弱光在部分处理下差异达显著水平,灌浆结实21d后,复合胁迫与单一弱光、低温部分差异显著,弱光与低温无显著差异。不同处理间的糙米率、精米率和整精米率均表现为NN>WN>LN>LW,其中,灌浆结实21d内,复合胁迫及单一低温、弱光较对照NN差异极显著或显著,灌浆结实21d后,部分时间段差异显著或极显著。低温弱光复合胁迫及单一胁迫对加工品质影响程度按大小依次为整精米率、精米率、糙米率,且灌浆结实21d内处理的影响大。对蒸煮食味品质,低温弱光复合胁迫极显著或显著降低了稻米的直链淀粉含量、胶稠度、外观、黏度和食味值,显著或极显著提高了蛋白质含量和硬度,单一胁迫低温、弱光表现与复合胁迫相同的影响,且灌浆结实21d内,除2016年的胶稠度,单一低温、弱光较对照NN差异显著或极显著,单一低温、弱光较复合胁迫差异也多显著或极显著。从水稻RVA谱特征值来看,低温弱光复合胁迫及单一胁迫造成稻米的峰值黏度、热浆黏度与崩解值下降,最高黏度、消减值与峰值时间上升,除灌浆结实29~35d的崩解值外,复合胁迫较对照NN差异达极显著或显著水平,部分指标的低温、弱光较对照NN差异也达显著水平。总之,灌浆结实期各时间段的低温弱光复合胁迫及单一胁迫造成稻米品质不同程度下降,且以灌浆结实21d内复合胁迫的影响较大。

侧深施氮对水稻产量及氮素吸收利用的影响

水稻机插侧深施肥是一种高效、优质、安全的栽培技术。深入研究侧深施肥条件下不同施肥方式对水稻产量及氮素利用效率的影响,有利于完善水稻侧深施肥技术体系。本研究以江苏优质食味水稻代表性品种南粳9108和南粳5718为材料,设置4种不同的侧深施施肥方式,分别为:100%基肥侧深施FM1(fertilization method 1)、70%基肥侧深施+30%分蘖肥FM2(fertilization method 2)、70%基肥侧深施+30%穗肥FM3(fertilization method 3)、35%基肥侧深施+35%分蘖肥+30%穗肥FM4(fertilization method 4),并设置常规施肥对照CFM(conventional fertilization method)和不施氮处理0N(no nitrogen)。研究了不同施肥方式(处理)对水稻产量及构成因素、茎蘖动态、叶面积指数、光合势、干物质积累、群体生长率、氮素利用效率等方面的影响。结果表明,与其他处理相比,FM3和FM4在稳定穗数的基础上,显著提高了群体颖花量和千粒重,经济产量最高。FM3生育中、后期的叶面积指数和干物质积累量尤其是抽穗至成熟期的干物质积累显著高于其他处理,拔节后的氮素积累量和全生育期总吸氮量、氮素农学利用率、氮素生理利用率、氮素吸收利用率、和氮素偏生产力也均显著高于其他处理。同时,FM3比CFM及FM4减少施肥次数1~2次,节省了用工及成本,利于规模化生产,是一种兼具高产、轻简与高效的水稻施肥方式。

江淮下游不同播期对稻–麦周年作物产量、品质及温光资源利用的影响

对江淮下游稻麦两熟高产优质种植模式周年气候资源分配和利用特征的探究,可以为当地机插水稻–小麦周年产量和气候资源利用效率的提高提供一定的理论依据。在泰州兴化市,水稻季以迟熟中粳南粳9108和中熟中粳连粳11为材料,设置5月22日(R-Ⅰ)、5月29日(R-Ⅱ)和6月5日(R-Ⅲ) 3个播期,小麦季以冬小麦宁麦13为材料,设置11月5日(W-Ⅰ)、11月15日(W-Ⅱ)和11月25日(W-Ⅲ) 3个播期,分析了不同播期下机插水稻–小麦周年高产优质形成与稻季、麦季资源分配特征。结果表明,水稻季,随着播期推迟,迟熟中粳南粳9108产量、温光资源量及其生产效率均显著下降,中熟中粳连粳11温光资源量呈下降趋势,但产量及温光利用率呈先升后降趋势,各播期迟熟中粳产量均高于中熟中粳。小麦季,产量、温光资源量及其生产效率均随播期推迟有不同程度降低。从周年生产看,周年稻麦产量随两季作物播期的推迟显著降低,其中迟熟中粳南粳9108播期R-Ⅰ与小麦播期W-Ⅰ组合在所有处理中产量最高。水稻产量占周年产量比例最高为62.99%,最低为55.86%。两季间积温分配率水稻季最高为68.38%,小麦季最高为34.14%。季节间辐射量分配率水稻季平均为51.7%,小麦季平均为48.3%。周年积温生产效率和光能生产效率随着稻麦播期推迟,呈下降趋势,播期越迟减少越显著。品质方面,迟熟中粳南粳9108的加工品质均随着播期推迟变劣而外观品质变优,中熟中粳连粳11加工品质变优而外观品质变劣。两品种蒸煮食味品质及营养品质(除中熟中粳连粳11食味值外)均随播期推迟变劣。小麦的湿面筋含量和蛋白质含量均随播期推迟而减少。通过优化稻麦播栽期,选用适宜生育期水稻品种,可提高周年产量和光温资源生产效率,是提升江淮下游机插水稻–冬小麦模式生产力的有效技术途径。

Effects of nitrogen level on yield and quality of japonica soft super rice

Although studies on the balance between yield and quality of japonica soft super rice are limited, they are crucial for super rice cultivation. In order to investigate the effects of nitrogen application rate on grain yield and rice quality, two japonica soft super rice varieties, Nanjing 9108(NJ 9108) and Nanjing 5055(NJ 5055), were used under seven N levels with the application rates of 0, 150, 187.5, 225, 262.5, 300, and 337.5 kg ha^(–1). With the increasing nitrogen application level, grain yield of both varieties first increased and then decreased. The highest yield was obtained at 300 kg ha^(–1). The milling quality and protein content increased, while the appearance quality, amylose content, gel consistency, cooking/eating quality, and rice flour viscosity decreased. Milling was significantly negatively related with the eating/cooking quality whereas the appearance was significantly positively related with cooking/eating quality. These results suggest that nitrogen level significantly affects the yield and rice quality of japonica soft super rice. We conclude that the suitable nitrogen application rate for japonica soft super rice, NJ 9108 and NJ 5055, is 270 kg ha^(–1), under which they obtain high yield as well as superior eating/cooking quality.

优化控释尿素施用方式提高沙质低肥力土壤水稻产量和品质

【目的】苏北黄河故道带低肥力沙性土壤保水保肥能力差,研究控释尿素施用技术对水稻产量和稻米营养品质与口感的影响,为该地区水稻优质生产的肥料管理提供科学依据。【方法】以中熟中粳水稻品种'苏秀867'为材料,在苏北黄河故道带低地力沙性土壤上进行了2年田间试验。采用裂区设计,主区为控释肥和尿素复混全部基施(BC)与控释肥和尿素复混基施+穗肥施用尿素(BC+PU)2种施肥方式;副区为3种树脂包衣尿素,控释天数分别为80天(CR80)、100天(CR100)和120天(CR120),控释肥与普通尿素复混比例为6∶4,BC处理所有肥料一次性基施,BC+PU处理中普通尿素一半基施一半穗期追施,总施氮量为270 kg/hm2,以常规尿素定量分施(CK)为对照,共7个处理。调查水稻产量及其构成因素、茎蘖动态、叶面积指数、干物质积累,测定稻米加工品质、外观品质、营养与蒸煮食味品质、淀粉RVA谱特征值。【结果】BC和BC+PU两区各处理水稻产量表现为CR80>CR100>CR120。相同控释尿素处理下,BC+PU处理的产量高于BC处理。BC+PU区3个控释肥处理以CR80的增产效果最好,两年产量分别为9.64和10.73 t/hm^(2),较CK处理分别增产5.32%和5.81%,这主要归因于其在稳定穗数的基础上,提高了总颖花量和结实率,且CR80处理的水稻中后期的叶面积指数和干物质积累量均较高,尤其是成熟期的叶面积指数显著大于CK,有利于光合产物积累。无论BC还是BC+PU施用方式,3个控释肥处理的稻米加工品质无显著差异。在外观品质和蒸煮食味方面,BC+PU区CR80处理与CK相比没有显著差异,而BC区CR80处理的直链淀粉含量、胶稠度和食味值较CK有所提高,RVA谱特征值中的峰值黏度、热浆黏度、最终黏度和崩解值上升,蒸煮食味品质较好;BC和BC+PU两区中,CR100和CR120处理的蛋白质含量均有不同程度的提高,垩白粒率和垩白度降低,稻米直链淀粉含量和食味值下降,RVA谱特征值中的峰值黏度、热浆黏度、最终黏度和崩解值下降,蒸煮食味品质较差。与BC处理相比,BC+PU处理稻米的外观品质和营养品质有所提升,蒸煮食味品质降低。【结论】在苏北黄河故道带沙性土壤上,采用释放期为80天的控释肥与尿素混合,采用基施+穗期追施尿素两次施肥方法,能够实现水稻的高产优质,但是降低蒸煮食味品质,而该缓释肥与尿素混合全部基施,虽然产量不是最高,但不会影响加工品质,且提高了蒸煮食味品质。

Effects of Nitrogen Application Levels on Ammonia Volatilization and Nitrogen Utilization during Rice Growing Season

We conducted field trials of rice grown in sandy soil and clay soil to determine the effects of nitrogen application levels on the concentration of NH4+-N in surface water,loss of ammonia through volatilization from paddy fields,rice production,nitrogen-use efficiency,and nitrogen content in the soil profile.The concentration of NH4+-N in surface water and the amount of ammonia lost through volatilization increased with increasing nitrogen application level,and peaked at 1-3 d after nitrogen application.Less ammonia was lost via volatilization from clay soil than from sandy soil.The amounts of ammonia lost via volatilization after nitrogen application differed depending on the stage when it was applied,from the highest loss to the lowest:N application to promote tillering > the first N topdressing to promote panicle initiation(applied at the last 4-leaf stage) > basal fertilizer > the second N topdressing to promote panicle initiation(applied at the last 2-leaf stage).The total loss of ammonia via volatilization from clay soil was 10.49-87.06 kg/hm2,equivalent to 10.92%-21.76% of the nitrogen applied.The total loss of ammonia via volatilization from sandy soil was 11.32?102.43 kg/hm2,equivalent to 11.32%-25.61% of the nitrogen applied.The amount of ammonia lost via volatilization and the concentration of NH4+-N in surface water peaked simultaneously after nitrogen application;both showed maxima at the tillering stage with the ratio between them ranging from 23.76% to 33.65%.With the increase in nitrogen application level,rice production and nitrogen accumulation in plants increased,but nitrogen-use efficiency decreased.Rice production and nitrogen accumulation in plants were slightly higher in clay soil than in sandy soil.In the soil,the nitrogen content was the lowest at a depth of 40-50 cm.In any specific soil layer,the soil nitrogen content increased with increasing nitrogen application level,and the soil nitrogen content was higher in clay soil than in sandy soil.In terms of ammonia volatilization,the amount of ammonia lost via volatilization increased markedly when the nitrogen application level exceeded 250 kg/hm2 in the rice growing season.However,for rice production,a suitable nitrogen application level is approximately 300 kg/hm2.Therefore,taking the needs for high crop yields and environmental protection into account,the appropriate nitrogen application level was 250-300 kg/hm2 in these conditions.

Comparison of yield traits in rice among three mechanized planting methods in a rice-wheat rotation system

Understanding the differences in yield traits of rice among pothole seedling of mechanical transplanting(PSMT), carpet seedling of mechanical transplanting(CSMT) and mechanical direct seeding(MDS) is of great importance not only for rice scientists but also for rice farmers to develop a high-yield production system under mechanical conditions in a rice-wheat rotation system. However, such traits are yet to be studied among rice varieties of japonica-indica hybrid rice(JIHR), japonica conventional rice(JCR) and indica hybrid rice(IHR). Field experiments were conducted in 2014 and 2015, where six cultivars of the three rice types JIHR, JCR and IHR were grown individually with PSMT, CSMT and MDS methods, under respective managements for each method to achieve the maximum attainable yield. Results showed that(i) the PSMT significantly increased grain yield of JIHR by 22.0 and 7.1%, of JCR by 15.6 and 3.7% and of IHR by 22.5 and 7.4%, compared to MDS and CSMT on average across the two years, respectively. The highest yield was produced by the combination of JIHR and PSMT;(ii) high yield under PSMT was mainly attributed to large sink capacity and high-efficient dry matter accumulation. With sufficient panicles per hectare, the increase of spikelet number per panicle, especially the increase in spikelet number of the secondary rachis-branches was determined to be the optimal approach for developing a large sink capacity for rice under PSMT. The optimal tillers development, large leaf area index at heading stage, and high leaf area duration, crop growth rate and net assimilation rate during grain-filling phase could be the cause of sufficient dry matter accumulation for rice under PSMT;(iii) moreover, the PSMT favored plant growth as well as enriched the stems plus sheaths during grain-filling phase, as compared with CSMT and MDS. These results suggest that PSMT may be an alternative approach to increasing grain yield in a rice-wheat rotation system in the lower reaches of the Yangtze River in China.

Comparison of agronomic performance between inter-sub-specific hybrid and inbred japonica rice under different mechanical transplanting methods

Mechanical transplanting has been applied to rice cultivation to save labor costs and ease labor shortages in Asian countries, especially in China. However, little information is available related to the characteristics of agronomic performance when comparing inter-sub-specific hybrid rice(IHR) and inbred japonica rice(IJR) under mechanical transplanting method. In 2013 and 2014, field experiments were conducted using IHR(Yongyou 2640) and IJR(Wuyunjing 24) under two cultivation patterns, that is, pot seedlings mechanically transplanted(PS) and carpet seedlings mechanically transplanted(CS). Grain yield, yield components, leaf area index(LAI), leaf area duration(LAD), aboveground biomass, crop growth rate(CGR), nitrogen(N) uptake, and N accumulation were investigated. When compared with CS, PS displayed significantly increased grain yield for both varieties because the larger sink size allowed higher N accumulation from panicle initiation to maturity. Moreover, total aboveground biomass under PS increased significantly compared with that under CS; that is, higher photosynthetic productivity resulted from a greater LAI and higher LAD during the grain filling stage. Higher N absorption capacity in the middle and late growth periods resulted in significantly enhanced total N uptake under PS. When compared with IJR for both treatments, IHR generated 75.2% more grain yield. However, the characteristics creating high yield of IHR were different from those of IJR. Greater aboveground biomass production as well as higher N uptake and accumulation created higher grain yield in IHR than in IJR. These results suggest higher yield could be achieved using PS with IHR, attributing to exploit both yield superiority and productive potential.

Morphological and physiological traits of large-panicle rice varieties with high filled-grain percentage

Understanding the morphological and physiological traits associated with improved filling efficiency in large-panicle rice varieties is critical to devise strategies for breeding programs and cultivation management practices.Information on such traits,however,remains limited.Two large-panicle varieties with high filled-grain percentage(HF) and two check large-panicle varieties with low filled-grain percentage(LF) were field-grown in 2012 and 2013.The number of spikelets per panicle of HF and LF both exceeded 300,and the filled-grain percentage(%) of HF was approximately 90,while that of LF was approximately 75 over the two years.The results showed that when the values were averaged across two years,HF yielded 12.91 ha^(-1),while LF yielded 11.01 ha^(-1).HF had a greater leaf area duration,biomass accumulation and transport of carbohydrates stored in the culm to the grains from heading to maturity compared with LF.HF exhibited a higher leaf photosynthetic rate,more green leaves on the culm,and higher root activity during filling phase,especially during the middle and late filling phases,in relative to LF.The length of HF for upper three leaves was significantly higher than that of LF,while the angle of upper three leaves on the main culm was less in both years.Meanwhile,specific leaf weight of HF was significantly higher when compared with LF.In addition,the grain filling characteristics of HF and LF were investigated in our study.Our results suggested that a higher leaf photosynthetic rate and root activity during filling phase,greater biomass accumulation and assimilate transport after heading,and longer,thicker and more erect upper three leaves were important morphological and physiological traits of HF,and these traits could be considered as selection criterion to develop large-panicle varieties with high filled-grain percentage.

Effect of side deep placement of nitrogen on yield and nitrogen use efficiency of single season late japonica rice

Side deep placement of nitrogen plays an important role in improving rice yield and nitrogen use efficiency.Few studies have examined the effects of reducing the times of nitrogen(RTN)application and reducing the nitrogen rate(RNR)of application on rice yield and nitrogen use efficiency under side deep placement of nitrogen in paddy fields.Therefore,a field experiment of RNT and RNR treatments was conducted with nine fertilization modes during the 2018–2019 rice growing seasons in a rice–wheat cropping system of the lower reaches of the Yangtze River,China.Rice yield and nitrogen use efficiency were investigated under side deep placement of nitrogen.We found that under the same nitrogen application rate,the yield of RTN3 increased by 9.64 and 10.18%in rice varieties NJ9108 and NJ5718,respectively,compared with the farmers’fertilizer practices(FFP).The nitrogen accumulation of RTN3 was the highest at heading stage,at 11.30 t ha^(–1)across 2018 and 2019.Under the same nitrogen application rate,the N agronomic use efficiency(NAE),N physiological efficiency(NPE)and N recovery efficiency(NRE)of RTN3 were 8.1–21.28%,8.51–41.76%and 0.28–14.52%higher than those of the other fertilization modes,respectively.RNR led to decreases in SPAD value,leaf area index(LAI),dry matter accumulation,nitrogen accumulation,and nitrogen use efficiency.These results suggest that RTN3 increased rice yield and nitrogen use efficiency under the side deep placement of nitrogen,and RNR1 could achieve the goals of saving cost and increasing resource use efficiency.Two fertilization modes RTN3 and RNR1 both could achieve the dual goals of increasing grain yield and resource use efficiency and thus are worth further application and investigation.

稻米脂肪与品质的关系及其调控

脂肪是稻米第3丰富的重要营养组分,是稻米“能量棒”,是水稻生命活动所需能量的重要来源之一。但稻米中粗脂肪含量较少且提取困难,前人对于稻米脂肪的研究多集中于稻米脂肪与品质的关系以及稻米脂肪酸组成成分上,关于稻米脂肪含量和组分调控的研究较少。本文综述了水稻籽粒脂肪的种类及分布、合成和分解代谢及其调控途径,以及稻米脂肪含量及其脂肪酸组分与稻米品质尤其是稻米蒸煮食味品质的紧密联系和影响因素,展望了提高和改善稻米脂肪含量及其组分的技术途径,以期为稻米脂肪与品质协同改良提供帮助。

Temperature and solar radiation utilization of rice for yield formation with different mechanized planting methods in the lower reaches of the Yangtze River,China

Several studies have demonstrated the effect of planting methods on rice yield, but information on the climate resources is limited. This study aims to reveal the effects of planting methods on climate resources associated with rice yield in a rice-wheat rotation system in the lower reaches of the Yangtze River, China. Field experiments were conducted in 2014 and 2015 with two japonica, two indica hybrid, and two japonica-indica hybrid varieties grown under three mechanized planting methods: carpet seedling of mechanical transplanting(CT), mechanical direct seeding(DS), and pot-hole seedling of mechanical transplanting(PT). The rice yield and total dry matter under PT were greater than those under CT and DS methods. Besides, the entire growth duration and daily production showed significant positive relations with rice yield. Compared with CT and DS, the effective accumulated temperature and cumulative solar radiation of rice under PT were higher in phenological phases. In addition, the dry matter/effective accumulated temperature and solar energy utilization of rice under CT and DS were higher during vegetative phase and lower during reproductive and grain filling phases in contrast to PT. The mean daily temperature and mean daily solar radiation in the entire growth duration showed significant positive correlation with rice yield, total dry matter, and harvest index. This study demonstrated that when the mean daily temperature is <25.1°C in vegetative phase and >20.1°C in grain filling phase, rice yield could be increased by selecting mechanized planting methods. Most varieties under PT method exhibited high yield and climate resources use efficiency compared with CT and DS. In conclusion, the PT method could be a better cultivation measure for high rice yield, accompanied with high temperature and solar radiation use efficiency in a rice-wheat rotation system in the lower reaches of the Yangtze River, China.

不同类型水稻品种茎叶维管束与同化物运转特征

选用籼型杂交稻、籼粳杂交稻、籼型常规稻和粳型常规稻4种不同类型水稻品种,比较其穗颈和剑叶维管束特征、茎叶同化物运转特征,分析穗颈和剑叶维管束特征与茎叶同化物转运和产量形成的关系,探讨施氮水平对水稻穗颈和剑叶维管束特征和茎叶同化物转运的影响。结果表明,不同类型水稻品种间穗颈和剑叶维管束数量和解剖结构特征、茎叶非结构性碳水化合物(non-structural carbohydrates,NSC)转运存在基因型差异。4种不同类型水稻品种中,籼型杂交稻和籼粳杂交稻穗颈和剑叶维管束数量、平均横截面积和韧皮部面积较高,其茎叶NSC转运和产量也较高,其次是籼型常规稻,粳型常规稻的穗颈和剑叶维管束数量、平均横截面积和韧皮部面积最低,其茎叶NSC转运和产量也最低。水稻穗颈和剑叶维管束特征和茎叶NSC转运受氮水平的影响,低氮能够促进茎叶NSC转运,增施氮肥增加了穗颈和剑叶维管束数量、平均横截面积和韧皮部面积,但穗颈横截面维管束密度降低。相关性分析表明,水稻穗颈大、小维管束数量与茎叶NSC转运显著或极显著正相关,穗颈和剑叶大、小维管束数量、横截面积和韧皮部面积与产量显著或极显著正相关。因此,选择茎叶维管束系统发育较好的水稻品种,同时合理施用氮肥改善维管束特征,有利于茎叶同化物转运,提高产量。

氮密处理提高迟播栽粳稻资源利用和产量

苏中地区为稻麦两熟制地区,近年来受气候变化和稻虾综合种养规模扩大的影响,水稻迟播迟栽现象较为普遍,使水稻品种的生长发育等与光、温资源不匹配,成为制约水稻高产稳产的重要因素之一。本研究在迟播迟栽(6月12日播种、6月30日移栽)条件下,采用毯苗机插方式,设置4个纯氮施氮量(N_(0):0 kg hm^(-2);N_(240):240 kg hm^(-2);N_(300):300 kg hm^(-2);N360:360 kg hm^(-2))、3个穴栽苗株数(D_(3):3株苗、D_(4):4株苗、D_(5):5株苗)处理,以适播适栽期(5月29日)常规施氮量和穴栽苗株数处理(N300D4)为对照(CK),探究氮肥水平与穴栽苗数对迟播迟栽粳稻生长发育和产量形成的影响,为提升苏中地区迟播迟栽粳稻产量潜力和资源利用效率提供依据。结果表明,较CK相比,迟播迟栽条件下各处理产量均下降,主要原因是迟播迟栽处理群体颖花量显著降低,2年最高群体颖花量分别较CK分别降低11.94%和8.12%;迟播迟栽条件下温光资源利用率降低,植株吸氮量和氮肥利用率降低,导致干物质积累量降低。迟播迟栽条件下,除处理N_(360)D_(5)外,随着施氮量和穴栽苗株数的增加,产量增加。主要原因是提高了群体颖花量,抽穗期叶面积指数和高效叶比例,延长了生育期,从而提高了温光资源利用率,进而提高了成熟期干物质积累量,缓解产量下降;另外,氮肥利用率随施氮量增加呈先增加后下降趋势,N_(300)D_(5)处理氮肥利用率最大。因此,迟播迟栽条件下应首先考虑增加穴栽苗数,再适量增加氮肥施用量,可以缓解产量损失,并提高氮肥利用率。