关键词：
hybrid rice;inbred rice;N use efficiency;grain yield
摘要：
In order to understand the yield performance and nitrogen (N) response of hybrid rice under different ecological conditions in southern China, field experiments were conducted in Huaiji County of Guangdong Province, Binyang of Guangxi Zhuang Autonomous Region and Changsha City of Hunan Province, southern China in 2011 and 2012. Two hybrid (Liangyoupeijiu and Y-liangyou 1) and two inbred rice cultivars (Yuxiangyouzhan and Huanghuazhan) were grown under three N treatments (N1, 225 kg ha-1; N2, 112.5-176 kg ha-1; N3, 0 kg ha-1) in each location. Results showed that grain yield was higher in Changsha than in Huaiji and Binyang for both hybrid and inbred cultivars. The higher grain yield in Changsha was attributed to larger panicle size (spikelets per panicle) and higher biomass production. Consistently higher grain yield in hybrid than in inbred cultivars was observed in Changsha but not in Huaiji and Binyang. Higher grain weight and higher biomass production were responsible for the higher grain yield in hybrid than in inbred cultivars in Changsha. The better crop performance of rice (especially hybrid cultivars) in Changsha was associated with its temperature conditions and indigenous soil N. N2 had higher internal N use efficiency, recovery efficiency of applied N, agronomic N use efficiency, and partial factor productivity of applied N than N1 for both hybrid and inbred cultivars, while the difference in grain yield between N1 and N2 was relatively small. Our study suggests that whether hybrid rice can outyield inbred rice to some extent depends on the ecological conditions, and N use efficiency can be increased by using improved nitrogen management such as site-specific N management in both hybrid and inbred rice production.
作者机构：
[周雪峰; 曹放波; Shan S.-L.; 张瑞春; 谢小兵; 伍丹丹; 邹应斌; 陈佳娜; 黄敏] Agronomy College of Hunan Agricultural University, Changsha, 410128, China;[蒋鹏] Institute of Rice and Sorghum, Sichuan Academy of Agricultural Sciences, Deyang, 618000, China
通讯机构：
[Zou, Y.-B.] A;Agronomy College of Hunan Agricultural University, Changsha, China
关键词：
超级稻;低氮密植栽培;产量;干物质;氮素利用率
摘要：
为了研究低氮密植栽培对水稻分蘖发生及成穗率、干物质积累及其转化、氮素利用率和产量的影响,2012—2013年以超级稻Y两优1号为材料, 在湖南长沙和海南澄迈进行了施氮量(75、150、225 kg N hm~(–2))与栽插密度(68、40、27、19穴m~(–2)), 每穴苗数(单、双、三本穴~(–1))与栽插密度(40、27、19、14穴m~(–2))的大田栽培试验。结果表明, 在基本苗数相同或相近的条件下, 减苗增密在齐穗期和成熟期的干物质量及产量分别比增苗减密高10.5%、5.2%和2.9%, 有效穗数对产量的贡献最大, 达到显著水平; 在低氮密植条件下, 有效分蘖期缩短6 d左右, 分蘖成穗率、表观转化率、氮肥偏生产力和氮素籽粒生产效率分别提高10.9%、21.0%、150.6%和19.6%。在施氮量为75 kg N hm~(–2)的密植(40~68穴m~(–2))条件下, 齐穗期和成熟期的干物质量及长沙点产量分别比中、高氮(150~225 kg N hm~(–2))常规密度(19~27穴m~(–2))低3.2%、7.5%和1.2%, 但差异不显著, 而澄迈点产量在2012年和2013年分别比之低5.2%和高9.1%, 且差异均达显著水平。在施氮量为150 kg N hm~(–2)的密植条件下, 成熟期干物质量比高氮常规密度低1.7%, 但齐穗期干物质量和产量比高氮常规密度高10.3%和3.3%。因此, 超级稻采用低氮密植栽培, 在100~150 kg N hm~(–2)和40穴m~(–2)条件下提早了够苗期, 增加了有效穗数, 提高了分蘖成穗率和结实率, 加之齐穗期适宜的干物质积累和较高的表观转化率, 有利于高产的形成和氮肥利用率的提高。
摘要：
Tillering is an important agronomic trait for rice grain production. To evaluate yield and tillering response, Liangyoupeijiu(super hybrid rice) was grown in Hunan, China during 2011–2012 under different methods of tillage(conventional and no-tillage system) and crop establishment methods(transplanting at a spacing of 20 cm × 20 cm with one seedling per hill and direct seeding at a seeding rate of 22.5 kg ha-1). Our results revealed that, at maximum tillering(Max.) and at maturity(MA) stages, direct seeding(DS) resulted in 22% more tillers than transplanting(TP) irrespective of tillage system. Tiller mortality reached a peak between panicle initiation(PI) and booting(BT) stages, and was 16% higher under conventional tillage(CT) than under no-tillage(NT). Transplanting required 29% more time for the completion of tillering and less for DS. Tillering rate was 43% higher in DS than TP under either CT or NT. There was a positive correlation between panicle number per m2and maximum tiller number per m2, but not panicle-bearing tiller rate. The panicle bearing tiller rate was higher under DS than TP and higher under NT than CT. Tiller dry weight gradually increased up to heading(HD) stage, and was 14% higher under TP than DS. Leaf area(cm2tiller-1) gradually increased from Max. to HD stage and then decreased by 34% in conventional tillage transplanting(CTTP) and 45% in no-tillage transplanting(NTTP) from 12DAH–24DAH(days after heading), but was similar(35%) under DS under either CT or NT. Grain yield was higher under CTTP owing to the larger sink size(heavier panicle, more spikelets in per cm length of panicle) than under DS.
关键词：
Hill dry weight;hybrid rice;panicle number;stem dry weight;tillering duration;tillering rate
摘要：
To compare the tillering pattern of hybrid rice, multiple field experiments were conducted involving three hybrid rice cultivars (HS 995, HS 48 and LYPJ) with three nitrogen fertilizer levels during 2009 to 2011. The experimental sites were selected in the sub-tropical environments of Changsha, Hunan Province in China, and in tropical climate zones of Habiganj and Gazipur in Bangladesh. All parameters of this study were significantly influenced by the locations and mostly the cultivars as well as the N levels. Tests confirmed that (i) panicle number was highest in Hunan and LYPJ showed the superiority even under cross ecosystem. The higher panicle number was the consequential of higher tiller number in both the environments; (ii) tillering rate (TR) responded to higher tillering capability; (iii) lower tiller emergence resulted in low panicle number but showed the higher panicle production efficiency in HS 48 and vice versa in LYPJ; (iv) early tiller emergence at Hunan showed the advantage to higher panicle number; (v) dry weight of stem and hill was more than 60% higher in Hunan and 23% higher in Habiganj over Gazipur site and (vi) higher N dose generated significant increases in hill dry matter, higher tiller number as well as increased the panicle number. Our study suggested that selection should be emphasized on cultivars those boast of more potential to high TR and to produce more dry matter especially at early growth period even under low temperatures in a wider area basis adaptation.
摘要：
China's super hybrid rice breeding project has developed many new cultivars with great yield potential. However, rice yield depends not only on genotype but also on environment. In 2008 and 2009, field experiments were conducted to compare super hybrid rice grown in Changsha (normal-yielding) and Guidong (high-yielding), Hunan Province, China. Eight super hybrid rice cultivars, namely II-you 084, II-youhang 1, D-you 527, Liangyoupeijiu, Nei-2-you 6, Y-liangyou 1, Zhongzheyou 1 and Zhunliangyou 527, were evaluated in each site. Grain yield and some yield attributes were determined for each cultivar. On the average across cultivars, Guidong produced higher grain yield than Changsha by 18% in 2008 and 41% in 2009. The higher grain yields were mainly attributed to a simultaneous increase in sink and source. For the sink, Guidong had both more panicles per m2 and larger panicle size (spikelets per panicle) than Changsha, which resulted in larger sink size (spikelets per m2). For the source, Guidong produced greater biomass than Changsha. Longer growth duration, more tillers (panicles) per m2 and higher biomass per unit tiller height were responsible for the greater biomass production in Guidong. Liangyoupeijiu and Zhunliangyou 527 performed well in both sites. Liangyoupeijiu was characterized by large panicle size, while Zhunliangyou 527 had high spikelet filling percentage and grain weight. Our study suggests that further improvement in both sink and source should be possible in the normal-yielding subtropical environments if new rice cultivars are to be bred by selection for tillering (tiller number and size), and developing cultivars with high spikelet filling percentage and grain weight may also be a feasible approach to achieve high rice yield.
