东北地区春玉米关键生育期干旱对根系生长的影响

Effect of drought stress on root growth during the key growth periods of spring maize in Northeast China

利用锦州大型土壤水分控制试验场和根系观测系统开展东北地区春玉米拔节与抽雄期不同程度干旱胁迫试验,采用微根管方法观测春玉米根系的生长,研究春玉米不同发育期干旱胁迫对40 cm、120 cm和160 cm土壤深度根系分布的影响。结果表明:春玉米不同土壤深度直径为1 mm以下的细根多于粗根,40 cm土壤深度细根所占比例最大,与之相比,120 cm和160 cm土壤深度直径为1 mm以上粗根所占比例有所增大。春玉米拔节期干旱初期40 cm土壤深度根长密度(Root Length Density,RLD)随干旱加重而增大,干旱胁迫可以促进玉米根系向土壤深处生长;乳熟期后玉米上层根系因拔节期干旱而提前衰老;抽雄后干旱也可使玉米根系向更深层土壤伸展,但干旱出现过晚将减弱对根系生长的促进作用。此外,玉米长期干旱后复水可使根系在短时间内补偿性快速生长。

Based on the large farmland soil moisture control experimental and root observational field in Jinzhou and minirhizotron method, water stress treatments were carried out during jointing and tasseling stages of maize with the way of continuous no-water complementing for a long time. Dynamics of root distributions at the soil depth of 40 cm, 120 cm and 160 cm and their responses to drought stress （DS） were observed and investigated. Results show that the number of fine roots with the diameter below 1 mm is greater than that of thick roots and ac- counts for a large proportion at the soil depth of 40 cm. The proportions of thick roots at the soil depth of 120 cm and 160 cm increase compared with those at shallow soil layer. At the early stage of DS, root length density （RLD） at the soil depth of 40 cm is increasing with the aggravated DS and the DS promotes roots growing toward deep soil layer. In addition, after tasseling stages, the roots in the upper soil layer indicate premature and acceler- ated aging when suffering the DS in jointing stage. Moreover, the DS during tasseling stage of maize is able to prompt roots growing toward deep soil layer too, but the later DS results in the effect of DS on root growth weak- ened. Besides, a quick and compensatory growth of root is possibly caused by re-watering after maize suffering a long DS.