高产栽培条件下种植方式对超级稻根系形态生理特征的影响

摘要

为探明高产栽培条件下不同种植方式对超级稻根系形态生理特征的影响,以超级稻品种淮稻9号和徐稻3号为材料,对旱育中苗壮秧精量手栽、小苗机插、直播3种种植方式水稻的根系形态生理特征进行了比较研究.结果表明:(1)不同种植方式超级稻产量差异极显著,与手栽相比,机插和直播分别减产5.05%和13.68%.(2)群体根数,直播>机插>手栽,但随生育进程差异越来越小,总根长拔节期直播>机插>手栽,抽穗期和成熟期,机插>手栽>直播;单茎根数不同种植方式间差异较小,总根长手栽>机插>直播,不同方式间差异大都达到显著水平;每条根长手栽和机插间差异不显著,均显著高于直播,根直径手栽>机插>直播,不同方式间差异显著.(3)群体根系干重拔节期机插和直播间差异不显著,均极显著高于手栽,抽穗期不同方式间差异均不显著,成熟期手栽>机插>直播,不同方式间差异极显著,抽穗后根系干重衰减率直播>机插>手栽,不同方式间差异显著;单茎根系干重拔节期、抽穗期和成熟期均手栽>机插>直播,不同方式间差异大都达到极显著水平,抽穗后根系干重衰减率直播与机插间差异不显著,均显著高于手栽;地上部干重手栽、机插、直播依次减小,根冠比则依次增大.(4)与手栽相比,机插和直播根系主要分布在0~10cm的土层内,特别是直播,65%的根系分布在0~5cm的土层内;0~5cm土层根系干重占根系总干重的比例手栽、机插、直播依次增大,5~10cm、10~15cm和15cm以下均依次减小.(5)群体根系吸收面积拔节期差异不显著,抽穗期手栽>机插>直播,不同方式间差异极显著,成熟期手栽和机插间差异不显著,均极显著高于直播;单茎根系吸收面积拔节期和成熟期手栽与机插间差异不显著,均极显著高于直播,抽穗期手栽>机插>直播,不同方式间差异极显著.(6)抽穗后群体根系伤流强度手栽、机插、直播依次增大,单茎根系伤流强度则依次减小.说明不同种植方式对超级稻的根系形态生理特征有明显影响,每条根长和根直径的不同以及根系在土层中的分布不同是不同种植方式水稻根系性状的两个显著特征.与手栽和机插相比,直播根系分布浅,每条根长和根直径小,群体根数多,但单茎根系总长短,根系干重低,吸收面积和抽穗后伤流强度小;机插与手栽相比,根直径小,根系分布浅,抽穗后群体和单茎根系干重低、下降快,单茎根系总长和伤流强度小.%A field experiment was conducted to compare the root system morphological and physiological characteristics of two super rice cultivars (Huaidao9 and Xudao3) using three planting methods, I.e., precision artificial transplanting with dry nursery middle and strong seedlings (AT), mechanical transplanting with small seedlings (MT) and direct seeding (DS). Results were as follows. (1) Yields of super rice under different planting methods were very significantly different. Compared with AT, yields of MT and DS reduced by 5.05% and 13.68%, respectively. (2) The population root number was DS>MT>AT, while the difference was decreasing with the growing process. Total population root length was shown to be DS>MT>AT at jointing and MT>AT>DS at heading and maturity. Root number per stem showed no significant difference among different planting methods, and total root length per stem was AT>MT>DS with generally significant difference. Length of single root was of no significant difference between AT and MT, though both were significantly higher than DS. As for root diameter, the result was AT>MT>DS and the difference among different planting methods was significant. (3) Population root dry weight showed no significant difference between MT and DS at jointing, that both had the extremely significantly higher value than AT. There was no significant difference among different planting methods at heading, but when at maturity it was AT>MT>DS and the difference was very significant. As for decreasing rate of population root dry weight after heading, it was DS>MT>AT with significant difference. Root dry weight per stem was AT>MT>DS through jointing, heading and maturity, and the difference among different planting methods was mostly very significant. Decreasing rate of root dry weight per stem after heading displayed no significant difference between DS and MT, but both of them had the significantly higher value than AT. Shoot dry weight reduced in order for AT, MT, and DS, but root-shoot ratio increased in the same order. (4) Compared with AT, roots of MT and DS were mainly distributed within the soil layer of 0-10 cm underground, especially for DS, the root proportion in 0-5 cm soil layer could sum up to 65%. Ratio of root dry weight in 0-5 cm soil layer to total root weight increased in order for AT, MT, and DS, while the ratios in the soil layers of 5-10 cm, 10-15 cm and >15 cm reduced in that order. (5) Population root absorption area showed no significant difference among different planting methods at jointing, performed as AT>MT>DS at heading with very significant difference, and, at maturity, showed no significant difference between MT and AT, both of which had the very significantly higher value than DS. Root absorption area per stem was of no significant difference between AT and MT at jointing and maturity while both had the very significantly higher value than DS, and was AT>MT>DS at heading with very significant difference. (6) Population root bleeding intensity after heading increased in order for AT, MT, and DS, but root bleeding intensity per stem reduced in the same order. The results suggested that planting methods have significant influence on root morphological and physiological characteristics of super rice. The different single root length and diameter and the difference in root distribution pattern in soil layer are two most significant characteristics of rice roots under different planting methods. Compared with AT and MT, the DS method develops roots of shallower distribution, smaller single root length and diameter and higher population root number, though with shorter total root length per stem, lower root dry weight, and less absorption area and bleeding intensity after heading. Compared with AT, root diameter of MT was smaller, distribution shallower, after heading root dry weight of plant population and of single stem both lower and declining faster, and total root length and bleeding intensity per stem inferior.