低温潜沼性逆境下不同耐受能力水稻根系动态变化

水稻根系生长分布与地上部生长及产量形成密切相关,定量研究低温潜沼性逆境下水稻根系分布特征对改进稻田管理方式及耐潜品种的选育等具有重要意义。以4个耐潜等级的8个水稻品种为实验材料,在水稻栽培环境模拟系统中连续栽植3年(2012—2014年),研究水稻根系在低温潜沼性逆境下的动态变化规律和分布规律,明确低温潜沼性逆境下水稻根系变化与产量构成的关系。结果表明:1)低温潜沼性逆境下水稻根系长度和数量的M值(绝对变化率)均大于0,P值(相对变化率)均小于0。表明,低温潜沼性逆境下水稻根系仍有一定增长,但与非低温潜沼性逆境相比,根系长度和数量均显著降低,降低程度因品种耐潜等级的高低而不同,耐潜指数高的品种(泸优5号和C优130)降低程度显著低于耐潜指数低的品种(川谷优204和协优027)。2)低温潜沼性逆境对0—10 cm土层根系的影响在5月底6月初最大;对10—30 cm土层根系的影响在6月底最大;对30—50 cm土层根系的影响在6月30日前后最大。3)低温潜沼性逆境下,水稻孕穗-抽穗期根系长度和数量与穗粒数、实粒数、结实率、产量之间呈显著正相关;与单株有效穗数和千粒重呈显著负相关,根系长度和数量的M值与P值,尤其是白根长度和数量的M值与P值可作为一个水稻耐潜能力评价指标进行考虑。4)低温潜沼性逆境下,不同土层水稻根系与产量构成因素间的相关性不同。0—10 cm土层根系长度和数量与有效分蘖数呈显著负相关;10—20 cm土层白根长度和数量与结实率呈显著正相关;30—50 cm土层根系长度和数量与着粒数呈显著正相关。

The law of root changing of different rice varieties with different tolerance capacity under low temperature and gleization soil environment

Both root growth and distribution are closely related to the growth of above ground organs, which subsequently affects the yield and quality of rice. It is important to understand the characteristics of root growth and distribution under environment of LTGS (low temperature and gleization soil), with the objectives of improving the management of rice fields and enhancing the tolerance capacity of rice under LTGS stress. Field experiments were carried out from 2012 to 2014 with 8 varieties (4 tolerance grades) of rice that were planted in a rice cultivation simulation system. The results showed that:1) The M (rate of absolute change) values for root number and root length were both higher than 0,whereas their P (rate of relative change) values were both lower than 0. These results demonstrate that although the root number and root length of rice plants are reduced, the roots can still grow under LTGS conditions. The decreased rate of root growth under LTGS environment varied among different rice varieties:it was significantly lower for Luyou 5 and Cyou 130, which both have a higher tolerance capacity for LTGS stress in comparison to Chuanguyou 204 and Xieyou 027. 2) Under LTGS environment, the crucial period for root growth at 0-10 cm soil was during the period from late May to early June; at 10-30 cm soil, the crucial period was late June; and at 30-50 cm soil, it was around June 30. 3) Under LTGS conditions, root number and root length both had a positive correlation with grains per panicle, number of filled grains, seed setting rate, and rice yield; and both had a negative correlation with effective panicle number and 1000-grain weight, during booting and heading stages. Therefore, root length and root number, especially those of white roots, can be used as an indicator to evaluate the tolerance capacity of rice to LTGS stress. 4) Under LTGS conditions, the correlations between root characteristics and yield composition differed among various soil layers. Total root number and total root length in 0-10 cm soil had a negative correlation with the number of effective tillers. White root number and white root length in 10-30 cm soil had a positive correlation with seed setting rate. Total root number and root length in 30-50 cm soil had a positive correlation with grains per panicle.