Forthcoming Articles http://www.ricesci.cn EN-US http://www.ricesci.cn/EN/1001-7216/current.shtml http://www.ricesci.cn 1001-7216 http://www.ricesci.cn/EN/abstract/abstract3110.shtml 【Objective】To explore the germplasm and gene resources of rice with high nitrogen efficiency, and reveal their molecular mechanisms and genetic effects, are the important contents and goals of the current research on rice nitrogen use efficiency (NUE). 【Methods】In order to identify the variant loci and candidate genes related to rice NUE, we collected 190 Asian rice accessions as an association population. By filtering and screening, 3,934,195 high-quality single nucleotide polymorphisms (SNPs) were obtained. Under field conditions, two levels of nitrogen treatments were set up: low nitrogen (N₁, 90 kg·hm^-2) and normal nitrogen (N₂, 180 kg·hm^-2). The phenotypic data of rice leaf width in response to low and normal nitrogen treatments were investigated at the maturity stage. Genome-wide association analysis (GWAS) was performed by combining FarmCPU and MLM models. 【Results】 By calculating the phenotypic ratio Q (N₁/N₂) of leaf width under low and normal nitrogen levels based on the leaf width phenotypic data of plants in response to different nitrogen levels, Q value showed the characteristics of the normal distribution. A total of 100 significant loci were identified on 12 chromosomes by GWAS for Q value, and 39 candidate QTLs were determined, including the cloned NUE-related genes OsNR1.2 and OsNAC42. The superior haplotypes and potential advantageous haplotype combinations of the candidate genes OsNR1.2 and OsNAC42 were further identified, providing valuable resources and information for rice NUE improvement. 【Conclusion】This study revealed the genetic basis of rice leaf width under different nitrogen treatments by using GWAS and haplotype analysis, and identified the candidate QTLs and genes related to NUE, including OsNR1.2 and OsNAC42. By combining haplotype analysis, the advantageous haplotype combinations of the two genes were identified, providing valuable resources and information for rice NUE improvement.

]]> http://www.ricesci.cn/EN/10.16819/j.1001-7216.2020.9049 【Objective】To investigate the effects of straw returned and nitrogen fertilizer management on nitrogen accumulation, transport, nitrogen use efficiency and grain yield of direct seeding hybrid rice after wheat / rape.【Methods】Yixiangyou 2115, three-line hybrid ricewith high quality ,was selected.The two-factor split zone design was adopted.The experiment was carried out simultaneously in wheat and oil stubble fields. The treatment was completely the same. The main area was that wheat /rape straw returned to the field (M1) and straw not to return (M0),sub-plot with four treatments of nitrogen fertilizer management : no nitrogen control (N0), base fertilizer: tillering fertilizer: flower promotion fertilizer: flower preservation fertilizer =1.0: 0: 0 (N1), 3: 3: 2: 2 (N2), 2: 2: 3: 3 (N3), respectively. The nitrogen accumulation and grain yield of each organ of main growth stage of direct seeding hybrid rice were analyzed.【Results】The results showed that under the two rotation methods, nitrogen fertilizer management had significant or highly significant regulatory effects on nitrogen accumulation in main growth stage , nitrogen transportation of stem, sheath , leaves after full heading stage and nitrogen use efficiency of rice plants of direct seeding hybrid rice. Straw returned significantly increased nitrogen accumulation, nitrogen transport of stem, sheath ,leaves and nitrogen use efficiency in the middle and late stage of hybrid rice under wheat /rape stubble . The agronomic use efficiency, partial productivity and apparent utilization efficiency of nitrogen fertilizer increased by 34.96% 28.76%, 2.52% 2.61% and 31.91% 22.30%, respectively. Meanwhile. the nitrogen accumulation of growth phrase and yield of direct seeding hybrid rice with rape straw returned were better than those of wheat straw returned, and the grain yield increased 481kg/hm2 (5.22%).It could effectively increase the rate of nitrogen accumulation in each stage of direct seeding hybrid rice ,promote the transportation of nitrogen from stem, sheath and leaves to panicle in productive stage and nitrogen accumulation amount of rice plant at mature stage was obvious advantage and high nitrogen use efficiency (nitrogen agronomic use efficiency, partial productivity and apparent nitrogen use efficiency of wheat / oil stubble rice reached 17.87kg/kg/17.85kg/kg, 67.27kg/kg/71.28kg/kg, respectively.74.93% 75.05%) under straw returned combined with base fertilizer: tillering fertilizer: flower promoting fertilizer: flower protecting fertilizer= 3: 3: 2: 2 and not to return to the field with base fertilizer: tillering fertilizer: flower promoting fertilizer: flower keeping fertilizer =2: 2: 3: 3..Therefore, the high yield was made.【Conclusion】Under wheat/rape-rice rotation, the straw returned to the field in full amount, combined with the nitrogen fertilizer management of the ratio of basal fertilizer: tiller fertilizer: flowering fertilizer: flowering fertilizer 3:3:2:2, could effectively improve the nitrogen absorption and utilization efficiency of direct seeding hybrid rice and increase the grain yield. Particularly the effect of returning to the field with rape straw was optimum.

]]> http://www.ricesci.cn/EN/abstract/abstract2629.shtml For the experiment of rice seedling physiological indexes, dry matter accumulation, root morphology and nitrogen (N) absorption characteristics after 0-48 hours and 1~29 days of root damage, through root-cutting 0/3, 1/3, 2/3, 3/3(control), 4 kinds of different level of root-cutting treatments under different seedling-ages (25 days and 40 days) before transplanting to the whole seedling root, with super hybrid rice F 498 as material and using dry nursery seedling raising manners. The results show there is different influence degree and reaction speed after root-cutting of different seedling-ages, proline and soluble sugar content showed significant peak after root-cutting of the seedlings under the two seedling-ages, root-cutting level is stronger with the higher peak, physiological resistance of 25 days seedling-age of seedlings after the root-cutting and recovery ability are significantly better than that of 40 days seedling-age of seedlings. From the root-cutting level see, root-cutting 1/3 treatment on seedling growth and even have a certain role in promoting of different seedling ages, 25 days of seedling-age with the treatment of root-cutting 1/3 after root-cutting 22 days, root length, surface area, shoot and root dry weight and the ratio of root to shoot is greater than that in the control. At the same time, N accumulation is significantly higher than that of control. The root surface area decreases with the increases of the root-cutting level in the whole period of 40 days seedling-age, and the root-cutting 1/3 treatment root shoot ratio is significantly greater than that of the control after root-cutting treatment in 22 days, also the shoot and root dry weight, root length, nitrogen accumulation and N content are greater than the control after treatment 29 days. The large degree of root-cutting will not only lead to the inhibition of root growth, but also will inhibit the absorption of nutrients seriously, so as to affect the growth and development of rice seedlings. This research provides the basis of the effect of rice seedling early growth and regreen survival under the rice injuring root transplanting seedlings

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