Seedling mode plays a crucial role in the rice production process, as it significantly affects the growth and development of seedlings. Among the various seedling modes, the seedling tray overlapping for seed emergence mode (STOSE mode) has been demonstrated to be effective in enhancing seedling quality. However, the impact of this mode on the germination and growth of seeds with varying plumpness remains uncertain. To investigate the effect of the STOSE mode on seedling emergence characteristics, growth uniformity, and nutrient uptake of seeds with varying plumpness levels, we conducted a study using super early rice Zhongzao 39 (ZZ39) as the test material. The seeds were categorized into three groups: plumped, mixed, and unplumped. The results indicated that the STOSE mode significantly improved the seedling rate for all types of seeds in comparison to the seedling tray nonoverlapping for seed emergence mode (TSR mode). Notably, the unplumped seeds exhibited the most pronounced enhancement effect. The soluble sugar content of the seeds increased significantly after 2 days of sowing under the STOSE mode, whereas the starch content exhibited a significant decrease. Furthermore, the STOSE mode outperformed the TSR mode in several aspects including seedling growth uniformity, aboveground dry matter mass, root traits, and nutrient uptake. Overall, the STOSE mode not only promoted the germination and growth of plumped and mixed seeds but also had a more pronounced impact on unplumped seeds.

High temperatures cause physiological and biochemical changes and significantly affect young panicle development of rice (Oryza sativa L.). Brassinosteroids play important roles in enhancing crop stress resistance. In this study, we subjected rice cultivars Huanghuazhan (heat-resistant) and IR36 (heat-sensitive) to high temperature (HT, 40 ºC) or normal temperature (NT, 33 ºC) for 7 d at the panicle initiation stage, in conjunction with application of 24-epibrassinolide [EBR, a synthetic brassinolide (BR)] or brassinazole (BRZ, a BR biosynthesis inhibitor) at the beginning of the treatments. HT exacerbated spikelet degeneration and inhibited young panicle growth, which were partially prevented by EBR application, while BRZ application aggravated the reduction in spikelet number. HT decreased the contents of BR, active cytokinins (aCTK), active gibberellins (aGA) and indole-3-acetic acid (IAA), but increased the content of abscisic acid (ABA) in young panicles. The activities of key enzymes involved in sucrose hydrolysis, glycolysis and the tricarboxylic acid cycle in young panicles were decreased with the change of endogenous hormone levels under HT. In addition, the contents of H2O2 and malondialdehyde (MDA) were increased and the activities of antioxidant enzymes were decreased in young panicles. Exogenous application of EBR induced the expression of phytohormone biosynthesis-related genes and down-regulated the expression of phytohormone catabolism-related genes to increase the contents of endogenous BR, aCTK, aGA and ABA, thus promoting the decomposition and utilization of sucrose in young panicles, enhancing the activities of superoxide dismutase, catalase and peroxidase, and reducing the accumulation of H2O2 and MDA in young panicles, whereas application of BRZ had the opposite physiological effects. These results showed that brassinosteroids mediate endogenous phytohormone metabolism to alleviate HT injury at the panicle initiation stage in rice.

A field variety screening experiment was carried out in the early rice season with 9 representative early japonica rice varieties from Northeast China and local main early indica rice Zhongzao 39（control） as materials to screen early japonica rice varieties suitable for cultivation in Southeast Zhejiang. The grain yield and rice quality of different early japonica rice varieties in Southeast Zhejiang were observed, and the perspectives of the growth period, seedlings quality, tillering characteristics, and utilization of temperature and sunshine resources were compared. The results showed that the average yield of the 9 early japonica rice varieties tested was 14.5% lower than that of the control, only Zhenbaodao 1 increased and reached a significant level compared with Zhongzao39. The reason for the reduction was related to the significant reduction of grains per panicle. The processing quality（except head milled rice rate）, appearance quality and cooking quality of early japonica rice were better than those of the control, mainly in the indexes of brown rice rate, chalky grain rate, chalkiness, transparency, gel consistency and amylose content. Compared with Zhongzao39, the growth stages of early japonica rice were advanced and the growth period was shortened, the seedling quality was improved, the tillering ability was strong, and the effective tiller percentage, the sunshine hours and the effective accumulated temperature production efficiency were slightly decreased, but the effective accumulated temperature was significantly increased.According to the results of comprehensive comparative tests, Zhenbaodao 1, Longgeng 18-2, Longgeng 1656, Kongyu 131 and Tong35 were suitable cultivated for double-cropping early rice in Southeast of Zhejiang.

In order to clarify the effect of precision drill sowing in machine transplanting for single-season hybrid rice to improve yield of sparsely planted population. The indica/japonica hybrid rice ‘Yongyou1540’ was used as the material， and two seeding rate treatments of standard 9-inch seedling tray (45.7g/tray， R 1 ; 60.5g/tray， R 2 ) and two machine transplanting specifications (30cm×21cm， D 1 ; 30cm×18cm， D 2 ) were set to compare the tillering characteristics， dry matter accumulation and yield formation of rice population between precision drill sowing （PS） and traditional broadcast sowing （BS） in machine transplanting. The results showed that， （1） the increase of seeding rate in seedling tray reduced the dry matter accumulation and plumpness of rice seedling， PS significantly improved the seedling quality; （2） compared with BS， PS significantly reduced the missing hill percent by 11.1 percentage point， meanwhile increased the percentage of hill of 2～3 seedlings transplanted by 109.7%; （3） PS increased the tillering rate and the number of tillers at tillering peak stage of rice population， especially under the low seeding rates， and the number of tillers at tillering peak stage and the productive tillers were higher in D 2 compared to D 1 ， and the number of peak tillering seedlings and productive tillers were the highest under R 1 D 2 PS; （4） The dry matter accumulation of rice population presented as PS＞BS， R 1 ＞R 2 ， D 2 ＞D 1 among the treatments， and the treatment of R 1 D 2 PS presented the highest dry matter accumulation. （5） PS enhanced the rice yield by increasing the number of productive panicles， compared to BS， PS increased the rice yield by 13.8% in average. Increasing of planting density increased the number of productive tillers， but slightly decreased the number of spikelet per panicle. PSR 1 D 2 presented the highest rice yield. In summary， precision drill sowing promoted the tiller occurrence， and increased the number of productive panicles and dry matter accumulation of sparsely planted population， and then increased the yield.

幼儿图式理论在让·皮亚杰提出后,在继任者实践中不断发展.现在,幼儿游戏图式逐步被广泛认为可以作为幼儿成长和学习能力发展的重要指标之一.通过研究幼儿游戏图式,教师可以在观察幼儿行为中得到更有针对性的信息,形成有效的环境支持方案,提出科学的指导策略.因此,我们将探讨如何根据幼儿的游戏图式特征及发展需要,制订出合理的教研活动计划.

为明确水稻机插育秧叠盘出苗的保湿效应及对秧苗生长特性及均匀度的影响,以甬优1540为供试品种,利用基质和稻田土进行播种育秧试验,分别设置育秧土饱和含水量的55％～60％(T1,基质含水量为38％,稻田土含水量为24％),75％～80％(T2,基质含水量为54％,稻田土含水量为32％)和饱和含水量(T3,基质含水量为70％,稻田土含水量为40％)3个育秧土播种水分梯度,播种后进行60 h叠盘出苗处理,并以不叠盘出苗育秧处理为对照,考查叠盘出苗期间育秧土含水量、种子出苗、秧苗特性及均匀度的变化.结果表明:(1)通过叠盘出苗能够保持出苗期间育秧土水分的稳定,不叠盘出苗育秧基质水分每小时散失1.08％,稻田土水分每小时散失1.29％;(2)叠盘出苗的种子出苗率显著高于不叠盘出苗处理,出苗期间育秧土水分含量与出苗率呈现显著正相关;(3)与不叠盘出苗育秧相比,叠盘出苗基质育秧和稻田土育秧分别使种子成苗率提高了 29.9％和39.1％,并增加了株高和叶龄,同时分别使秧苗均匀度增加了 23.6％和23.9％.试验说明,水稻机插育秧种子出苗期间进行叠盘能够维持育秧土水分稳定,进而提高种子成苗率、秧苗质量及秧苗均匀度.

In order to ascertain the beneficial effects of precision drill sowing (PS) in machine transplanting with long seedling age of double cropping late season hybrid rice. In this study, seed of Yongyou 1540 (YY1540) was subjected to precision drill sowing of 16 rows (PS-16, 45.7 g tray-1), precision drill sowing of 18 rows (PS-18, 60.5 g tray-1) and traditional broadcast sowing (BS, 60.5 g tray-1) in standard seedling tray at the same day. Seedling ages of 20, 25, 30, and 35 days were set for machine transplanting to analyze the rice seedling quality, machine transplanting characters, rice population growth, and yield formation between PS-16, PS-18, and BS. The results were as follows: (1) PS improved the light transmittance of seedling population, compared to BS, PS enhanced the seedling quality and increased the percentage of seedlings with tillering buds, among the treatments, PS-16 got the best seedling quality and highest percentage of seedling with tillering buds. (2) Compared to BS, PS significantly reduced the missing hill percent and increased the ratio of hills with 2-3 seedlings transplanted, and there was no significant difference between PS-16 and PS-18. Seedling age prolonging increased the root injury degree and seedling injury rate, and decreased the seedling survival rate after machine-transplanting, in which, PS-16 had the minimal increasing in root injury degree and seedling injury rate, meanwhile PS-16 got the highest survival rate of seedling machine-transplanted. (3) The seedling age prolonging postponed the rice growth duration by increasing the duration of seedling rejuvenation period. Among the seedling age treatments, the shortest period of rejuvenation period was observed in PS-16, and then the growth period minimal delayed in PS-16 with the seedling age prolonging. (4) PS effectively promoted plant tillering, and PS-16 got the best effect. The number of tillers at 10 d after machine transplanting of PS-16 machine was 16.4% and 20.8% higher than that of PS-18 and BS, in average. Seedling age prolonging decreased the tiller number at tillering peak stage, and the tiller number at tillering peak stage was PS-16>PS-18>BS at different seedling age treatments. The productive tiller percentage presented no difference among the sowing methods and seedling ages. (5) Seedling age prolonging decreased the leaf area index and dry matter accumulation by the degree of PS-16PS-18>BS under different seedling age treatments, in average. In conclusion, compared to BS, PS could improve the seedling quality, reduce the missing hill percentage in machine transplanting, improve the machine transplanting quality, shorten the seedling rejuvenation period, promote plant tillering, and increase the leaf area index and dry matter accumulation, and then effectively reduce the yield loss of double late season hybrid rice with long seedling age in machine transplanting, and the benefits of PS-16 were better than that of PS-18.

【Objective】The aim of this study was to clarify the beneficial effect of precision drill sowing (PS) in machine transplanting for improving the population uniformity and yield of hybrid rice under low seeding rate, and to establish the theory and technology for machine transplanting with sparse sowing and fewer seedling in machine transplanting with flat seedling of hybrid rice.【Method】Indica-japonica hybrid rice ‘Yongyou 1540’ was used in this study, and the experiment was conducted at Chonghua country (Yuhang district) and experimental base of China National Rice Research Inistitute (Fuyang district) at the same time. PS was layout set at 18 horizontal hills×40 vertical hills in the standard seedling tray for machine transplanting. The sowing amount per hill in seedling tray was set as 2.5 seeds (43.2 g/tray, T1), 3.5 seeds (60.5 g/tray, T2), and 4.0 seeds (69.1 g/tray, T3), and the same seeding rates in traditional broadcast sowing (BS) for machine transplanting were set as the control. Then, the seed distribution, seedling quality, machine planting quality, dry matter accumulation in rice population, the uniformity of the number of productive tillers and yield formation were investigated.【Result】(1) Compared with BS, PS improved the uniformity of seed distribution in seedling tray. (2) PS significantly enhanced rice seedling quality, and increased the dry matter accumulation and uniformity of seedling. PS increased the seedling uniformity by 47.5% on average among different seeding rates than that under BS, which presented a more beneficial effect with low seeding rates. (3) Compared with BS, PS reduced the missing hill percent in machine transplanting by 8.9 percentage point on average, and PS enhanced the uniformity of seedling number transplanted per hill by 87.8% on average, meanwhile, the percentage of hills with 2-3 seedling transplanted was the highest at T2 under PS. (4) PS increased the number of tillers at tillering peak stage to increase the number of productive panicles in rice population. Among the different seeding rate treatments, PS increased the number of productive tillers by 6.7% on average, meanwhile, which enhanced the uniformity of the number of productive tillers by 40.2%, in which T2 presented the highest productive tillers and productive tillers uniformity, meanwhile PS enhanced the leaf area index and dry matter accumulation of rice population. (5) PS enhanced the rice yield by 9.0% on average compared with BS by increasing in the number of productive tillers, in which T2 presented the highest yield. With the increasing of seeding rate, the increasing rate of yield under PS in contrast to BS presented a reduction tendency, while a decreasing was observed in the contribution rate of machine-transplanted seedlings to yield. (6) Correlation analysis showed that the population uniformity of the number of productive tillers positive correlated to leaf area index, dry matter accumulation and rice yield.【Conclusion】Precision drill sowing in machine transplanting improved the uniformity of seed distribution, reduced the missing hill percent, increased the uniformity of seedling transplanted per hill, therefore contributed to enhance the rice population uniformity and yield. Precision drill sowing was an effective method to achieve higher yield with flat seedling in machine transplanting under low seeding rates of hybrid rice.

Due to rainfall, closed weeding of paddy fields and other reasons, submergence stress often occurs during the germination and emergence stages of direct-seeded rice (Oryza sativa L.), which leads to intensified anaerobic respiration, accelerated consumption of stored nutrients, difficulty in germination of rice seeds, uneven emergence of seedlings and varying yields. Recent advances in the understanding of phytohormone interaction and the regulation of signaling pathways in crops have increased the feasibility of modulating responses to phytohormones in crop plants to enhance adaptation to environmental changes. In this review, we summarize recent advances and progress in the understanding of the regulation of phytohormone signaling pathways and their interactions with diverse internal and external signaling cues under submergence. We also discuss how these physiological modulations of phytohormones and their abundant signaling crosstalk can be applied to enhance the submergence tolerance of direct-seeded rice during germination through the manipulation of seedling morphogenesis and the fine-tuning of stress responses. Finally, we discuss how complex phytohormone signaling pathways could regulate the metabolism of stored nutrients, anaerobic respiration and energy supply in submerged direct-seeded rice seeds, thereby improving their submergence tolerance. This review hopes to provide a basis for studies of the tolerance mechanisms of submerged direct-seeded rice and the promotion of the simplified direct-seeded rice cultivation model.

[目的]为明确水稻机插育秧覆盖土厚度对秧苗生长的影响.[方法]以甬优1540和天优华占为材料,利用9寸标准机插秧盘进行试验,利用基质和稻田土进行播种,设置3个育秧土覆盖厚度处理(T1,底土2 L+覆盖土2 L;T2,底土3 L+覆盖土1 L;T3,底土3.6 L+覆盖土0.4 L),考察秧苗成苗率,苗高和叶龄、以及干质量和秧苗充实度的变化.[结果](1)秧盘覆盖土过厚不利于秧苗成苗,T2处理秧苗成苗率最高,采用基质育秧的种子成苗率要好于采用稻田土育秧.(2)叶龄变化和育秧土覆盖厚度密切相关,叶龄表现由高到低依次为T1、T2和T3,同时基质育秧的叶龄大于稻田土育秧.T1和T2处理苗高差异不明显,但均高于T3处理,2个品种间以及基质类型间趋势一致.(3)T2处理秧苗均匀度平均比T1和T3处理高33.8％和41.0％,T2处理弱苗比例最低,分别比T1和T3处理平均降低51.7％和74.3％,2个品种趋势一致,其中基质育秧秧苗均匀度高于稻田土育秧.(4)基质育秧秧苗干质量高于稻田土育秧,其中T1和T2处理干质量差异不大,但均显著高于T3处理.T2处理秧苗充实度最高,两个品种在两种育秧土间的表现趋势一致.[结论]在水稻机插育秧时,秧盘覆盖土要有适当的厚度,9寸盘播种底土3 L,覆盖土1 L有最佳的效果.

南方杂交稻机插目前仍然以毯苗育秧机插为主,采用撒播育秧,无法实现杂交稻稀播少本种植,制约了杂交稻的推广以及杂交稻机插产业化的提升.在多年对毯苗机插技术研究的基础上,中国水稻研究所研发了精准播种育秧机插技术,突破了杂交稻毯苗育秧机插技术的瓶颈.该技术改变传统流水线撒播为定向定位条播,显著降低了机插播种量,提高了机插秧苗质量.同时配套相应机插技术实现了杂交稻少本均匀种植,漏秧率降低到5％以下,并提高了机插群体均匀度.2019年和2020年示范试验结果表明,精准播种育秧机插技术可节省用种量29.2％,提高产量10.2％,节本增效显著.

全球水稻生产数据分析表明,1961年至2018年全球水稻面积、单产和总产年均增幅分别为0.67％、1.65％和2.33％,受多种因素制约,近年单产和面积增长幅度变小.水稻在亚洲、非洲、美洲、欧洲和大洋洲均有种植,其中,亚洲水稻种植面积占比为87.9％,非洲占7.7％、美洲占4.0％,欧洲和大洋洲不到0.5％.近10年与上世纪60年代相比,全球水稻种植面积和总产区域间分布已发生变化,非洲水稻面积增长,亚洲水稻面积下降.1961年至2018年全球水稻总产增长因子分析表明,总产增长的60％～70％来自单产的提高,各洲水稻总产增长贡献因子存在较大差异.

于2017—2019年在浙东单季稻区2种类型土壤(象山淡塘泥田和鄞州青紫泥田)上开展定位试验,以4个甬优籼粳杂交稻品种(甬优1540、甬优7850、甬优12、甬优538)和2个常规粳稻品种(宁84和秀水134)为材料,设置HN(农民习惯施氮量,杂交稻折纯N 240 kg·hm-2、常规稻折纯N 200 kg·hm-2)、MN(在HN基础上减氮17％)、LN(在HN基础上减氮34％)和N0(不施氮对照)4个处理,研究不同处理下水稻产量和氮肥利用率的差异.结果表明,水稻产量在2个试验点均随着施氮量的减少而下降,MN处理下象山和鄞州的甬优籼粳杂交稻平均产量分别达10.8 t·hm-2和9.9 t·hm-2,仅比HN处理减少1.2％和2.6％,且无显著性差异;与HN相比,MN和LN处理下水稻有效穗在2个试验点均有一定程度的下降,但结实率和千粒重在象山试验点增加.相关性分析表明,甬优籼粳杂交稻产量在象山试验点(中等肥力)与有效穗、每穗粒数和高峰苗呈显著(P<0.05)正相关,而在鄞州试验点(高肥力)与有效穗、结实率和成穗率呈显著(P<0.05)正相关.对于中等肥力土壤,不同氮肥处理对甬优籼粳杂交稻的氮肥农学利用率无显著影响,但氮肥农学利用率随着试验年限的增加快速提升,表明在当地试验条件下,如不采取其他技术措施,持续减少氮肥投入存在一定风险.在浙东沿海地区常规单季稻栽培条件下,甬优系列籼粳杂交稻上氮肥施用量减少17％可以保证产量,但氮肥减量应综合考虑耕地基础地力、品种特性和肥料利用率等因素的长期效应.

Global climate change affects crop yields and endangers food security. High yielding rice varieties adapted to climatic changes is a key breeding objective. However, little is known regarding the impact of climate change on the yield potentials and resource utilization efficiencies of modern rice cultivars in Eastern China. Using two-year field experiment, we investigated the biomass, nitrogen (N) uptake, and yield in relation to climatic resource use efficiencies of eight representative Chinese mid-season indica rice (Oryza sativa L.) cultivars grown in the Middle Lower Yangtze Area over the last fifty years. The yield potential of rice from 1961-2015 was simulated using the ORYZA (v3) model. The total thermal time (growing degree days) increased at a rate of 3.3 degrees C yr(-1), while sunshine hours decreased at a rate of 2.4 h yr(-1) over the past five decades during growth period. Compared with the average potential yield from 1961 to 1975, an average 5.65 % of reduction occurred across different cultivars from 2001 to 2015. However, the rice potential yield increased by 52.0 kg ha(-1) yr(-1) in the released cultivars with increasing years of release. The use efficiencies of sunshine hours and thermal time for the cultivar Yangliangyou6 released in 2001 increased by 68.5 % and 59.5 % compared with the cultivar Shenglixian released in 1938. The increase of potential yield in the released cultivar Yangliangyou6 was attributed to increase utilization efficiency of radiation. Modern cultivars (semi-dwarf and super rice) maintained greater leaf area index (LAI) during the filling period without modification in photosynthetic rate. Besides, the decrease in grain N concentration contributed to stay-green characteristic and to the efficient use of N in modern cultivars. Thus, modern indica rice cultivars tolerate the adverse climatic changes by optimizing plant productivity and increasing resource utilization efficiencies.

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Rice (Oryza sativa) spikelet formation is dependent on carbohydrate metabolism. High temperature inhibits young panicle growth and spikelet formation, and brassinolides (BRs) are involved in the regulation of spikelet formation. Elucidation of the mechanism by which endogenous BRs mediate carbohydrate metabolism to influence spikelet formation under high temperature may provide a theoretical and technical basis to alleviate heat injury. In this study, rice cultivar 'IR36' was subjected to high temperature (HT; 40 degrees C) or normal temperature (NT; 33 degrees C) for 7 days at the panicle initiation stage in conjunction with application of exogenous 2, 4-epibrassinolide (EBR) and brassinazole (BRZ) at the beginning of the treatments. HT inhibited spikelet differentiation and aggravated spikelet degeneration to reduce the number of spikelets per panicle. Exogenous EBR reduced the decrease in spikelet number induced by HT, whereas exogenous BRZ enhanced the reduction in spikelet number. Analyses of the transcript levels of genes associated with BR biosynthesis and decomposition showed that HT promoted BR decomposition to reduce the endogenous BR content. HT blocked sucrose transport from leaves to young panicles, and inhibited the activities of crucial enzymes involved in sucrose hydrolysis, glycolysis, and the tricarboxylic acid cycle to reduce sugar utilization. In addition, HT reduced the activities of antioxidant enzymes and increased the contents of hydrogen peroxide and malondialdehyde. Exogenous EBR application promoted sucrose transport to young panicles and improved sucrose utilization under NT and HT, whereas application of BRZ resulted in the opposite physiological response. These results show that inhibition of spikelet formation owing to decreased sugar utilization under HT is associated with BR decomposition.

为探讨滨海盐碱地不同氮肥用量对水稻干物质积累和转运、稻谷产量及品质的影响,以常规中粳中晚熟品种圣稻2620为试验材料,在含盐量3‰～6‰条件下研究了6种氮肥施用方式(N5,40 kg/667 m2;N4,32 kg/667 m2;N3,24 kg/667 m2;N2,16 kg/667 m2;N1,8 kg/667 m2;N0,不施氮肥)对水稻干物质积累和转运及产量、品质的特性.结果表明,随着氮肥用量的提高,水稻生殖生长期占全生育期的比例由N0的23.67％增长至N5的25.00％,营养生长期占全生育期的比例由N0的76.33％减少至N5的75.00％,全生育期由N5的180 d减少至N0的169 d.干物质积累盛期在返青期后25 d至抽穗后20 d,总体干物质积累速度表现为N5＞N4＞N3＞N2＞N1＞N0.茎鞘、叶片的干物质输出率、转化率随着氮肥用量的增加而增大,但减少20％的氮肥用量,不影响干物质的输出和转化.氮肥用量的提高可以显著提高稻米的加工品质和外观品质,但显著降低了其食味品质,食味值由N0的72分降低至N5的67分.氮肥用量提高可以显著提高水稻产量,由N0的388.34 kg/667 m2升高至N4的525.83 kg/667 m2,减少20％氮肥用量的N4处理比全氮量的N5处理产量提高4.39％.

Determination of the optimal fertilization method is crucial to maximize nitrogen use efficiency and yield of different rice cultivars. Side-deep fertilization with controlled-release nitrogen, in conjunction with machine transplanting and subsequent topdressing, was applied to Indica–japonica hybrid rice ‘Yongyou1540’ (YY1540) and indica hybrid rice ‘Tianyouhuazhan’ (TYHZ). Four nitrogen treatments were applied in 2018 and 2019: traditional nitrogen application with quick-release nitrogen (T1), single-dose deep fertilization at transplanting with 100% controlled-release nitrogen (T2), and deep fertilization of 70% controlled-release nitrogen and topdressing of 30% quick nitrogen at tillering (T3), or at panicle initiation (T4). Side-deep fertilization reduced the fertilizer application frequency without causing yield loss, T4 enhanced the yield of YY1540 by increasing the number of productive tillers and number of spikelets per panicle compared with T1, T2 and T3. The yield of TYHZ showed no significant difference among treatments. The T4 treatment decreased the number of tillers at the tilling peak stage and increased the percentage productive tillers and number of differentiated spikelets. Compared with the other treatments, T4 increased dry matter accumulation and leaf area index during panicle initiation and grain ripening, and contributed to enhanced nitrogen uptake and nitrogen utilization in YY1540. On average, nitrogen uptake and utilization in YY1540 were highest in T4, but no significant differences among treatments were observed in TYHZ. Dry matter accumulation and nitrogen uptake from panicle initiation to heading of YY1540 were correlated with number of spikelets per panicle, but no significant correlations were observed for TYHZ. Supplementary topdressing with quick-release nitrogen at the panicle initiation stage was required to increase yield of indica–japonica hybrid rice, whereas single-dose deep fertilization with controlled-release nitrogen is satisfactory for the indica hybrid cultivar.

研究旨在探讨滨海盐碱地缓释肥与无机肥配施情况下,氮素在各时期的用量分配对水稻生育期、生长特性、产量及食味品质的影响.以中粳中晚熟水稻品种'南粳9108'为试验材料,在3‰～6‰土壤盐分条件下,设计了5种施肥方式,在生育期的关键节点测定水稻的根系指标、叶面积指数、各部位干物质积累,并比较各施肥处理水稻的生长指标和食味品质.结果表明,配施缓释肥与无机肥且减少氮素用量20％的T3处理组,水稻的生殖生长期占全生育期的比例较全氮量施肥且施用无机肥的T1处理组缩短0.25％,营养生长期占全生育期的比例增长0.23％,全生育期减少2天.水稻的总根系长度、叶面积指数、单位叶面积干物质积累、单位面积茎鞘干物质及产量总体趋势为T3＞T1＞T2＞T4＞T5.稻米中蛋白质含量与食味值呈现负相关性,蛋白质含量越高,食味值越低;稻米中直链淀粉含量与食味值之间呈现负相关,直链淀粉含量越高,食味值越低.氮肥用量的提高显著降低了稻米的食味品质,不施用氮素的T5处理组食味值最高,配施缓释肥与无机肥处理土壤肥效增强,但稻米的食味值也最低.缓释肥与无机肥配施,减少氮素用量20％,且穗肥不追施任何氮素处理时,水稻的生长指标、稻米的食味值显著的提高.

[目的]明确精准条播育秧机插对籼粳杂交稻产量形成的影响及其在减氮条件下降低产量损失的作用.[方法]以甬优538和甬优1540为供试品种,精准条播(precision drill sowing,PS)16条机插,并以相同播种量传统撒播(broadcast sowing,BS)机插为对照,同时设置不施氮肥(0 kg/hm2,zero-nitrogen application rate,0N)、适氮(240 kg/hm2,suitable nitrogen application rate,SN)、减氮15％(204 kg/hm2,reduced nitrogen application rate,RN)等3个氮肥施用梯度处理,分析比较产量形成、植株均匀度、干物质积累及氮利用效率.[结果]1)与撒播相比,精准条播通过提高有效穗数使籼粳杂交稻产量平均提高4.3％,减氮条件下精准条播处理的水稻产量降幅小于撒播.2)精准条播显著降低漏秧率,提高机插苗数均匀度以及有效穗数均匀度.与撒播相比,精准条播处理提高减氮下高峰苗数,两个品种趋势一致.3)与撒播相比,精准条播增加抽穗期叶面积指数,同时增加了抽穗期和抽穗开花后的干物质积累和氮吸收总量,其中减氮处理下表现尤为明显.4)除0N外,氮素干物质积累量和氮素稻谷生产效率在不同品种方式及氮处理间无显著差异,但精准条播处理显著提高了氮肥吸收利用效率和氮肥农学利用效率,两个品种趋势一致.[结论]精准条播机插能够提高籼粳杂交稻植株均匀度,增加高峰苗数和叶面积指数,促进干物质积累和氮素吸收,进而提高产量,有效减少氮肥减施下籼粳杂交稻的产量损失.