作者机构：
[Denardin, Luiz Gustavo de O.; Martins, Amanda P.; Anghinoni, Ibanor] Fed Univ Rio Grande do Sul UFRGS, Interdisciplinary Res Grp Environm Biogeochem, Soil Sci Res Program, BR-91540000 Porto Alegre, RS, Brazil.;[Ciampitti, Ignacio A.; Bastos, Leonardo M.] Kansas State Univ, Dept Agron, Manhattan, KS 66506 USA.;[Moojen, Fernanda G.; Carvalho, Paulo Cesar de F.] Univ Fed Rio Grande do Sul, Grazing Ecol Res Grp, Anim Sci Res Program, BR-91540000 Porto Alegre, RS, Brazil.;[Huang, Min] Hunan Agr Univ, Coll Agron, Changsha 410128, Peoples R China.;[Chabbi, Abad] French Natl Res Inst Agr Food & Environm INRAE, URP3F, F-86600 Lusignan, France.
通讯机构：
[Chabbi, Abad] F;French Natl Res Inst Agr Food & Environm INRAE, URP3F, F-86600 Lusignan, France.
关键词：
Cattle grazing;Glycine max;Lowland;Paddy fields;Soil chemical properties
摘要：
The high nitrogen (N) application rates typically used in Chinese cropping systems have led to diminishing returns for yields and have also imposed substantial environmental costs. Here, we estimate that the annual N loss from rice production in China reached approximately 2.6×109 kg from 2011 to 2015, and we demonstrate that adoption of the mechanically dense transplanting technique by producers is an effective method to reduce N loss from rice cropping systems without suffering a yield penalty.
通讯机构：
[Huang, Min] H;Hunan Agr Univ, Coll Agron, Crop & Environm Res Ctr Human Hlth, Changsha 410128, Peoples R China.
关键词：
Amylose content;early season rice;grain quality;grain yield
摘要：
Eating quality is of paramount importance to rice (Oryza sativa L.) consumers and soft rice with low amylose content has become popular in China This study was conducted to evaluate the performance of soft rice grown in the early season (ES) dominated by non-soft rice. Field experiments were conducted in Yongan and Santang, Hunan Province, China from 2016-2018. Results showed that grain amylose content in soft rice cultivars was consistently lower in the ES compared to the late season (LS). The lower grain amylose content in the ES compared to the LS was partly attributed to higher average daily mean temperature during grain filling. No significant relationship was observed between grain yield and seed amylose content in ES rice. Soft rice cultivars produced a similar average grain yield to non-soft rice cultivars in the ES. These results encourage breeders to develop more ES rice cultivars with soft texture to meet the consumer demand for this type of rice.
作者机构：
[Xiaohong Yin; Jiana Chen; Long Fan; Zui Tao; Min Huang; Yingbin Zou] Crop and Environment Research Center, College of Agronomy, Hunan Agricultural University, Changsha, 410128 China
通讯机构：
[Min Huang] C;Crop and Environment Research Center, College of Agronomy, Hunan Agricultural University, Changsha, 410128 China
通讯机构：
[Huang, Min] H;Hunan Agr Univ, Coll Agron, Crop & Environm Res Ctr, Changsha 410128, Hunan, Peoples R China.
摘要：
Low light is a common environmental factor that adversely affects rice yields. This study was conducted to evaluate the combined effect of hill density and nitrogen (N) fertilizer rate on yield attributes in hybrid rice under low-light conditions. Field experiments were conducted in 2014 and 2015. Two hybrid rice cultivars (Y-liangyou 1 and Luoyou 9348) were grown under combinations of three hill density levels (high, 40 x 10(4) hills ha(-1); moderate, 27 x 10(4) hills ha(-1); low, 14 x 10(4) hills ha(-1)) and two N rate levels (high, 240 kg ha(-1); moderate, 143-148 kg ha(-1)), and shaded from heading to maturity. Grain yield was highest in the combination of high hill density and moderate N rate and significantly declined with decreasing hill density combined with increasing N rate for both cultivars in both years. Averaged across two cultivars and two years, grain yield declined by about 4% for each 10% decrease in hill density combined with each 10% increase in N rate. A significant reduction in spikelet filling percentage was observed with decreasing hill density combined with increasing N rate in Y-liangyou 1 in 2015 and Luoyou 9348 in 2014. The same trend was observed for grain weight in Y-liangyou 1 in 2014 and Luoyou 9348 in 2015. These results indicate that adopting the practice of decreasing hill density combined with increasing N rate can result in poor grain filling and consequently yield decline in hybrid rice under low-light conditions.
通讯机构：
[Huang, Min] H;Hunan Agr Univ, Coll Agron, Crop & Environm Res Ctr Human Hlth, Changsha, Hunan, Peoples R China.
摘要：
Glutelin and prolamin are the two major proteins in rice grains. Grain content of glutelin is considerably higher than that of prolamin in rice, but there is limited information on the factors determining the different grain contents of glutelin and prolamin. To address this knowledge gap, the present study compared final weight per grain and accumulation characteristics of glutelin and prolamin in four rice cultivars. Results showed that final glutelin weight per grain was 3.24-3.95 times higher than final prolamin weight per grain. Glutelin and prolamin accumulation processes were well fitted by the logistic equation. The initial, maximum, and mean accumulation rates of glutelin were 1.69-4.67 times higher than those of prolamin. The active accumulation duration of glutelin was 2.9-5.1 d longer than that of prolamin. These results indicate that both higher accumulation rate and longer active accumulation duration are responsible for the higher final weight per grain of glutelin compared to prolamin in rice.
通讯机构：
[Huang, Min] H;Hunan Agr Univ, Coll Agron, Crop & Environm Res Ctr, Changsha, Hunan, Peoples R China.
摘要：
Translocation of biomass produced during pre-heading to grains is a determinant of grain yield, but also plays an important role in adaptation to unfavorable environments during post-heading in rice. In this study, field experiments were conducted to determine the critical factors that regulate biomass translocation in rice. Biomass translocation and production characteristics of two rice hybrids (Guiliangyou 2 and Y-liangyou 1) were compared between two site-year environments (Naning-2014 and Yongan-2018). Results showed that biomass translocation parameters (biomass translocation amount and rate and contribution of biomass translocation to filled grain weight) and ratio of biomass production during pre-heading to post-heading (BPpre/BPpost ratio) decreased in Guiliangyou 2 but increased in Y-liangyou 1 with the environment change from Nanning-2014 to Yongan-2018. The decreased BPpre/BPpost in Guiliangyou 2 was attributable to increased biomass production during post-heading (BPpost), while the increased BPpre/BPpost ratio in Y-liangyou 1 was due to increased biomass production during pre-heading (BPpre). Higher cumulative incident solar radiation and larger diurnal temperature variation were responsible for the increased BPpost in Guiliangyou 2 and the increased BPpre in Y-liangyou 1 grown in Yongan in 2018 compared to in Nanning in 2014. The results of this study indicate that changes in biomass translocation and production with environment (climate) in rice are dependent on genotype and that the BPpre/BPpost ratio is an important factor regulating biomass translocation in rice.
摘要：
In order to solve the problem of labor shortage in double-season rice production areas, machine transplanting, as opposed to manual transplanting, has become the more popular alternative method in rice cultivation. However, the most existing late rice cultivars are not suitable for machine double-season rice cultivation due to their long duration of growth. Therefore, based on the previous studies we chose early season rice cultivars to meet the needs of machine double-season rice cultivation. In this study, field experiments were conducted during the late season in 2015 and 2016 in Liuyang County, Hunan Province, China. Grain yield and yield-related traits were compared among eight early-season cultivars (Liangyou 6, Lingliangyou 211, Lingliangyou 268, Zhuliangyou 819, Xiangzaoxian 32, Xiangzaoxian 42, Zhongjiazao 17, and Zhongzao 39) in 2015 and four cultivars (Lingliangyou 268, Zhuliangyou 819, Zhongjiazao 17, and Zhongzao 39) in 2016, selected from the highest yielding cultivars grown in 2015. Lingliangyou 268 produced 8-44% higher grain yield than did the other cultivars except Zhongjiazao17 in 2015. This higher grain yield was driven by grain weight and aboveground biomass. The greater aboveground biomass in Lingliangyou 268 was mainly attributed to higher apparent radiation use efficiency (aboveground biomass/incident solar radiation). Our study suggests that improvement in grain weight and apparent radiation use efficiency were critical to the high grain yield of early-season rice cultivars grown in late season under machine transplanting conditions.
通讯机构：
[Huang, Min] H;Hunan Agr Univ, Coll Agron, Crop & Environm Res Ctr, Changsha, Peoples R China.
摘要：
High yields of mechanized intensive rice-based cropping systems, e.g. double-season cropping using early- and late-season rice, are important to ensure national food security in China. However, few studies addressing the relationship between grain weight and grain yield of early-season rice under machine-transplanted conditions. A field experiment was conducted to determine the critical grain-filling characteristics and related physiological aspects that contribute to high grain weight in machine-transplanted early-season rice. The results showed that grain yield was significantly positively correlated with grain weight but not with panicles per m2, spikelets per panicle, and spikelet-filling percentage. Furthermore, this study demonstrated that there was a significant positive correlation between grain weight and mean grain-filling rate, which was significantly positively correlated with harvest index and grain cytokinin content. These results indicate that high grain-filling rate driven by good transport of assimilates to grains and strong grain sink strength is responsible for high grain weight in machine-transplanted early-season rice.
