Penetration of hardpans by rice lines in the rainfed lowlands
Penetration of hardpans by rice lines in the rainfed lowlands
复制标题
雨养低地稻株对硬土的渗透
DOI：
10.1016/s0378-4290(02)00038-2
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发表时间：
2002
影响因子：
5.8
通讯作者：
L. Wade
中科院分区：
文献类型：
--
作者：
B. K. Samson;M. Hasan;L. Wade
在潮湿的低地条件下，水稻的根通常很浅。机械阻抗是可能限制根系进入深层土壤的一个因素，从而降低了根系在晚季干旱期间从深层汲取水分的能力。1994年雨季在孟加拉国的拉杰沙希进行了水稻根系穿透硬土层的能力试验。八个品系（CT 9993、IR 52561、IR 58821、IR 62266、KDML 105、Mahsuri、Namsagui 19和IR 20）在三个实验中生长：早期灌溉、早期灌溉和晚期灌溉。抽穗期至面团期随着干旱程度的加重，两个试验中15- 25 cm土层的土壤渗透阻力均增加到3.0MPa。总根长的高比例被发现在表层，特别是在IR 20。CT 9993和IR 58821的根系较粗。根长密度（RLD）增加，在更深的土壤层中的干旱随时间的推移，但不同的行在他们的能力，穿透压实层干旱加剧抽穗后。只有IR 58821和Mahsuri能够在抽穗后将RLD增加到15 cm以下的值大于1.6cmcm−3，并且仅在早期试验中。IR 20、IR 52561和IR 62266在抽穗后土壤渗透阻力有增加的趋势，说明这些品系在抽穗后能够吸收15 cm以下的水分，但RLD没有随之增加。Mahsuri和IR 58821的更大的渗透能力在两种土壤渗透阻力高的土壤渗透环境中表达。
Rice roots are commonly shallow in rainfed lowland conditions. Mechanical impedance is one factor that may restrict access of roots to deeper soil layers, thereby reducing the capacity of the root system to extract water from depth during late-season drought. The capacity of rice roots to penetrate hardpans was examined in experiments at Rajshahi, Bangladesh, in the 1994 wet season. Eight lines (CT9993, IR52561, IR58821, IR62266, KDML105, Mahsuri, Namsagui19, and IR20) were grown in three experiments: irrigated early, rainfed early, and rainfed late. As drought intensified from heading to dough stage, soil penetration resistance increased to 3.0MPa at 15–25cm depth in both rainfed experiments. A high proportion of the total root length was found in the surface layer, particularly in IR20. CT9993 and IR58821 had thicker roots than other lines. Root length density (RLD) increased in deeper soil layers in rainfed with time, but lines differed in their capacity to penetrate the compacted layer as drought intensified after heading. Only IR58821 and Mahsuri were able to increase RLD below 15cm depth after heading to values greater than 1.6cmcm−3, and only in the rainfed early experiment. In rainfed late, soil penetration resistance tended to increase after heading in IR20, IR52561 and IR62266, implying these lines were able to extract water below 15cm depth, but without the concomitant increase in RLD. The greater penetration ability of Mahsuri and IR58821 was expressed in both rainfed environments at high soil penetration resistance.