不同生态条件下氮高效水稻品种干物质积累和产量特性

  【目的】  研究生态条件和施氮水平及其互作对氮高效水稻品种干物质积累、物质转运和产量的影响，为不同稻区不同施氮水平下选择适宜的水稻品种提供科学依据。  【方法】  本试验于2019年在四川省大邑县(弱光寡照)和云南省永胜县(光温充足)两个生态点进行，以西南地区大范围种植的10个水稻品种为供试材料，采用两因素裂区设计，主区为不施氮(N0)、低氮120 kg/hm2 (N120)和高氮180 kg/hm2 (N180) 3个施氮水平，副区为10个品种。分别于拔节期、抽穗期和成熟期测定干物重，计算不同时期干物质积累和转运量，于收获后测定水稻产量。  【结果】  水稻产量和干物质生产特性为生态条件、施氮水平、品种及其互作效应共同作用的结果。大邑生态点宜香优1108在N120下的产量比N180提高4.68%，永胜点德优4923在N120施氮水平下的产量比N180提高113.4 kg/hm2，结合产量和GGE模型分析，大邑生态点宜香优1108为低氮高效型，晶两优534和F优498为高氮高效型；永胜点德优4923为低氮高效型，中优295和丰优香占为高氮高效型。氮高效水稻干物质积累和转运特征因生态条件和施氮量的变化而变化。大邑低氮高效型品种产量主要来自拔节前干物质的积累和抽穗前光合产物的转化，产量优势在于足量的单位面积有效穗数，移栽至拔节期的群体生长率与产量(r=0.70**)和有效穗数(r=0.41*)呈显著正相关；大邑生态点高氮高效型品种抽穗至成熟期群体生长率和穗后干物质积累量对籽粒的贡献率明显高于其它品种，产量与抽穗至成熟期群体生长率(r=0.56**)和穗后干物质积累量对籽粒的贡献率(r=0.37*)呈显著正相关关系；永胜低氮高效型品种干物质积累特征在于拔节至抽穗期群体生长率和穗前干物质转化对籽粒的贡献率较高，千粒重较同处理平均值提高13.61%；永胜高氮高效型品种具有拔节至抽穗期高群体生长率的物质生产特性，产量优势在于较高的每穗颖花数，该点拔节至抽穗期群体生长率与产量(r = 0.60**)和每穗颖花数(r = 0.68**)均呈极显著正相关关系。  【结论】  在大邑等弱光寡照地区，低氮高效型品种应保证前期较高的生长速率和穗前干物质转化对籽粒的贡献率；高氮高效型品种应保持抽穗后高群体生长率并增加穗后光合产物的积累。在永胜等光温充足地区，拔节至抽穗期较高的群体生长率是低氮高效型和高氮高效型品种共同的物质生产特征。

Dry matter accumulation and yield characteristics of high-nitrogen efficient rice cultivars under different ecological conditions

  【Objectives】  This study examines the dry matter accumulation, material transportation and yield of N-efficient rice cultivars in response to ecological conditions and N application levels. We aim to provide a scientific basis for selecting suitable rice cultivars in different ecological regions.   【Methods】  Field experiments were conducted in two ecological sites; one with low light (Dayi County, Sichuan Province, DYS) and the other with sufficient light and temperature (Yongsheng County, Yunnan Province, YSY). Ten rice cultivars were used as test materials. Each cultivar was subjected to three N application levels (0, 120 and 180 kg/hm2). The rice dry matter accumulation (DMA) was measured at the jointing, heading, and maturity stages. The dry matter translocation's (DMT) contribution to yield was calculated and the rice yield was evaluated at harvest.  【Results】  The ecological condition, N level, cultivar, and their interaction affected rice yield and dry matter accumulation. Cultivar Yixiangyou 1108 in DYS and Deyou 4923 in YSY recorded higher yield at N120 than at N180. According to GGE model analysis, Yixiangyou 1108 was a low-N-efficient cultivar, Jingliangyou 534 and F-you 498 were high-N-efficient cultivars in DYS. Deyou 4923 was a low-N-efficient cultivar, Zhongyou 295 and Fengyouxiangzhan were high-N-efficient cultivars in YSY. The DMA and DMT of high-N-efficient cultivars were affected by ecological conditions and N levels. In DYS, the yield of low-N-efficient cultivar was driven by DMA and DMT before jointing, depending on the number of effective panicles per unit area. Pre-jointing population growth rate (PGR) was significantly and positively correlated with yield (r = 0.70**) and effective panicle number (r = 0.41*). In DYS, high-N-efficient cultivars had (P<0.05) higher DMT after heading and growth rate from heading to maturity compared to other cultivars. Rice yield was positively correlated with PGR from heading to maturity (r = 0.56**) and DMT after heading (r = 0.37*). The low-N-efficient cultivar in YSY had higher PGR from jointing to heading stage, higher DMT before heading, and the 1000-grain weight was 13.61% higher than the average value in the same treatment. In YSY, high-N-efficient cultivars had high PGR from jointing to heading stage. The yield advantage correlated to the high number of spikelets per panicle. The PGR from jointing to heading had a (P<0.05) positive correlation with yield (r = 0.60**) and spikelet number (r = 0.68**).  【Conclusions】  In low-light areas such as DYS, low-N-efficient cultivars' high yield is dependent on rapid PGR and high DMT before the heading stage. In contrast, high-N-efficient cultivars yield depends on high PGR and dry mater accumulation after the heading stage. In areas with adequate light and temperature, such as YSY, the higher PGR from jointing to heading stage was a common feature of low and high N efficient cultivars.