谷子根系对群体压力胁迫的生物学响应

采用根管土柱栽培的方法,比较了在相同根管土柱体积上种植不同株数谷子时谷子根系的主要特征,如根系数量,根系入土最大深度,根系SOD、POD活性,总根长,根系MDA含量及根系总吸收面积与活性吸收面积等对群体密度变化的可塑性.结果表明,不同群体下,谷子单株根数前期差异小,中后期差异大;而单位土体中的根量前期差异大,后期差异小.群体大(密度高),谷子根量、总根长及根系总吸收面积与活性吸收面积达到高峰的时间早,但衰亡时期也早,且入土深度较浅.群体小根量高峰出现得迟但维持的时间较长,根系在土体中的延伸深度也较大,有利于后期营养的获取和产量的提高.群体在作物生长中起着量的决定作用,而个体生长发育由于群体不同而引起质的差异.在生产上要想获得理想的产量,既要有足够量的保证,又要求达到一定质的标准,以使群体与个体协调发展.表4图2参18

Biological Response of Foxtail Millet Root System under Different Colony Stresses

Comparison of root system distribution and physiological characteristics of millet in a population density gradient changing from low (1 plant per soil column) to high (10 plants per soil column) density on the Experimental Farm of Shanxi Agricultural University was conducted. The main root characteristics, including numbers, maximal length, SOD activity, POD activity, MDA contents, total length, total and active absorbing area, and weight of root and canopy, were analyzed comparatively. Furthermore, the root plasticity of thel millet in response to its change in population densities was also discussed. The results showed that the growth density could significantly affect the growth of the millet root system. The root number per plant of the millet had small difference among the different population densities before the jointing stage, but the difference became large at the middle and later stages. The root number of unit volume of soil differed greatly among the different population densities at early stage, but small differences were observed at the later stage. Heavy colony could cause earlier appearance of growth peak time of root number, total length, and total and active absorbing areas. However, the millet roots under high density senesced much earlier and their length was shorter than those under low density. Light colony could help increase the root depth at later growth stage, so it could improve absorption of water and nutrition from deep soil at later growth stage, extend leaf function period of millet and increase the yield.Population was a decisive factor for crop growth quantity, while the status of individual crop in population of different densities had essential distinction. In order to gain a successful yield, the population and individual of the crop should be both considered. Tab 4, Fig 2, Ref 18