根区湿润方式对玉米根系生长发育的影响

Effects of partial root-zone irrigation on growth and development of maize root system

将厚塑料紧密地固定在盆栽试验用桶壁和底的中央,玉米种子播种于厚塑料布的正上方,在均匀灌水、固定部分根区灌水和根系分区交替灌水3种方式下,分期测定两个1/2根区根系的长度、面积、干重以及单位面积的平均根长和比根长,研究不同根区根系的生长发育特征。结果表明,处理40d时,与其他根区相比,固定灌水非灌水区的比根长和单位面积平均根长明显增大,说明土壤水分减少使根系直径变小。根面积、长度以及干重的增长速率均表现为,处理0～5d内,与均匀灌水及其非灌水区相比,两种局部灌水的灌水区均显著增大;处理10～15d内,交替灌水的灌水区较其他根区明显增大,固定灌水的灌水区与均匀灌水相近。固定灌水时,灌水区根系的面积、长度、干重及其增长速率较之非灌水区显著增大;交替灌水时,两个根区的增长速率呈交替变化,其绝对数值随时间延长趋于相同。表明交替灌水不仅可刺激供水区根系的补偿生长,而且对恢复供水区也有补偿效应,并能够促使不同根区的根系均衡发展。

Effects of partial root-zone irrigation on growth and development of maize root system from different root zones were studied using pot experiment. The pot was divided into two equal parts by a piece of plastic fixed in the central, which could prevent water penetration between two compartments, and maize was planted above the plastic so as to the root system to stretch into two compartments equally. Plants were irrigated on both halves of the container （ conventional irrigation, C） , on one side only （ fixed partial root-zone irrigation, F ）, or alternatively on both sides （ alternative partial root-zone irrigation, A）. The results showed that after 40 d of treating, the ratios of root length to dry root weight and to root area increased markedly for the non-irrigated root zone of F treatment when compared to the ratios of the other root zones, suggesting that the root diameter becomes small in drought soil. The increase rates of root length, root area and dry weight were significantly enhanced for irrigated zones of A and F during 0 --5 d of treating when compared to those of non-irrigated zones and C treatment. During 10 -- 15 d of treating, the increase rates for the irrigated zone of A were significantly higher than those of any other zone while there was no significant difference between irrigated zones of F and C. For F treatment, both the values and increase rates of root length, root area and dry weight in the irrigated zone were always significantly higher than those of the non-irrigated zone. For A treatment, the increase rates changed alternately and the values became equal at the end of the experiment. Our results suggest that for A treatment, significant compensation mechanisms of root growth in irrigated root zone occurred both when water were localized in part of the root system, and during the subsequent recovery from drought stress. Moreover, A treatment was beneficial for root system to grow evenly in different soil zones.