Differential Tolerances Among Tropical Forage Crops to Water Deficit Conditions.

本研究的目的是评价作物对水分胁迫的形态和生理适应性，以估计其抗旱能力。植物生长在绿色温室、田间条件和水培条件下，并经受一系列水分胁迫。水分胁迫对供试植物的生长发育有显著影响。在胁迫条件下，相对生长率（RGR）和净同化率（NAR）下降，作物品种之间存在显著差异。在水分胁迫条件下，RGR和NAR的降低百分比被用作耐旱性的指标。它低在罗德斯格拉斯和高在乔德的眼泪。而叶面积比（LAR）则不受胁迫的影响。水分胁迫使叶片光合速率降低，尤其是薏米。胁迫提高了草地早熟禾的水分利用效率，而显著降低了薏苡的水分利用效率。罗兹格拉斯能够保存照片 ...更多信息 胁迫下的合成产量，因此RGR和NAR与胁迫条件下的其他作物相比没有显著降低。高粱<14><14>和薏米在胁迫条件下，叶片和茎中的^ C同化物被修复，叶片向腐烂物的^ C同化物转移显著减少。薏米<14>中的高分子量组分如蛋白质和木质素-纤维素组分中的^ C含量明显降低。根系导水率（RAC）也因胁迫而显著延长。Rhodesgrass的RHC在那里的时间比约伯的眼泪长一倍。在水分胁迫下，^3H_2O在两种植物体内的移动均明显减少。加入^3H_2O后20 h，根、茎、展开叶和积水叶组织水的相对放射性分别为营养液的15%、45%、9.5%和8.5%。约伯泪中的相应值分别为48、17、5.1和3.8%。与灯心草相比，^3H_2O从根向地上部，特别是向叶片的运动受到强烈的限制。结果表明，不同树种对水分胁迫的抗性不同，这与其抗旱能力有关。植物对水分的抵抗主要表现在位于运输部位的茎节和茎基上，表现为从一个器官到另一个器官。少

The objective of this study are evaluation of morphological and physiological adaptation of the crops to water stress conditions to estimate their drought to lerant ability. Plant were grown foth in green house, field condition and water culture and subjected to sequence to water stress. The plant growth of tested plants was Affected remarkably due to water stress. The Relative Growth Rate (RGR) and Net Ossimilation Rate (NAR) decreased under stress conditions and significant differences were observed between crop species. The reduction percentage in RGR and NAR under water stress condition was used as an indicator of tolerances to drought. It was low in Rhodesgrass and high in Jod's tears. However, Leaf Area Ratio (LAR) was not effected by stress. The photosynthetic rate was reduced due to water stress, spedially in Job's tears. Water use efficiency in Rhodesgrass was increased by strees, whereas that of Job's tears was severely decreased. Rhodesgrass was capable of maintaining photos … More ynthetic production under stress and therefore RGR and NAR were not decreased considerably compared to other crops under stress conditions. ^<14>C aseimitates remedied in leaves and stems and the tanslocation of ^<14>C assimilates from leaves to rots was remarkably reduced under stress conditions in sorghum and Job's tears. ^<14>C content in high-molecular weight constituents such as protein and ligin-cellulose fraction in rots was apparently reduced by stress in Job's tears. And also root hydrautic conductivity (RAC) was considerably longer due to stress. The RHC of Rhodesgrass was there times longer than of Job's tears. The movement of ^3H_2O through plant were remerbobly reduced in both species under water stress. Twenty-Foun hours after added of ^3H_2O, the relative radioactivity in tissue water of root, stem, expanded leaves and ehponding leaves were 15, 45, 9.5 and 8.5% respectively, compared to that of nutrient solution on Rhodeagrass. The respective values in Job's tears were 48, 17, 5.1 and 3.8%. The movement of ^3H_2O from root to shoots, especially to leaves was strongly restrictebl in Job's tears compared to Rhodesgrass. The results indicated that the resistance to water how through plants differ among species according with their drought to lerant ability. The major resistance to water how through plant appers to be exist in the nodes and for the basal stems which are located in transit positions appears from organ to another. Less