Quantitative evaluation of differences in cultivar and fertilization to drought resistance of rice by stomata and soil water changes

本研究旨在通过对水稻气孔和土壤水分的测定，评价水分胁迫对水稻生长的影响，并定量阐明品种和施肥对水稻抗旱性的差异。在塑料大棚内种植水稻，采用悬挂灌溉方式进行水分胁迫。除了亚洲水稻外，还测试了非洲新稻（NERICA）品系。测定了气孔导度、各深度土壤含水量、地上部干重和根系性状，并比较了它们之间的关系。不同非洲新稻品系间的干重和产量差异较大，有些表现出比抗旱的亚洲稻品种更高的生长量。高生长的品种和品系表现出较高的气孔导度。亚洲水稻品种土壤含水量与干重呈负相关，表现出高生长吸水性的品种土壤含水量也高。相反，在非洲新稻品系中，它们之间没有相关性，并且似乎非洲新稻品系之间的水分利用效率存在很大差异，并且一些低吸水性的品系通过高水分利用效率表现出高生长。在亚洲水稻品种中，干物质生产与根系性状之间存在相关性，而在非洲新稻品系中，两者之间不存在相关性。亚洲水稻的抗旱品种通过吸收大量水分而表现出高生长。相反，非洲新稻品系的水分利用效率差异很大，有些品系似乎表现出高生长和低吸水性，它们似乎适合在干旱地区长期种植。在低肥水平下添加堆肥，可以减轻水分胁迫，保持较高的干物质生产。

The objective of this study is to evaluate the effects of water stress on the growth of rice by the measurements of stomata and soil water, and to clarify the differences in cultivar and fertilization to drought resistance quantitatively. Rice was grown in field under vinyl house and water stress was given with suspending irrigation. Besides Asian rice, NERICA (New Rice for Africa) lines were tested. Stomatal conductance, soil water content of each depth, top dry weight and root characteristics were measured and relationships between them were compared. There were large differences in dry weight and yield among NERICA lines, some showed higher growth than drought resistant Asian rice cultivars. Cultivars and lines with high growth showed high stomatal conductance. There was negative correlation between soil water content and dry weight in Asian rice cultivars, and in cultivars that showed high growth water absorption was high. In NERICA lines on the contrary there was no correlation between them, and it seems that there is large difference in water use efficiency among NERICA lines and that some lines with low water absorption show high growth by high water use efficiency. In Asian rice cultivars there was correlation between dry matter production and root characteristics, but in NERICA lines there was no correlation between them. Drought resistant cultivars in Asian rice showed high growth by absorbing much water. In NERICA lines on the contrary variation in water use efficiency is large and some seem to show high growth with small water absorption, and they seem to be appropriate for the long term cultivation in dry region. By adding compost in low fertilizer level, water stress was reduced and dry matter production was maintained high.