Effects of drought on photosynthesis and ear development characteristics of maize

Maize is one of the grain crops with a large demand of water. Its ear period from jointing stage to anthesis stage is the critical period of its life. It is significant meaningful to study the response mechanism of ear stage to drought stress for improving drought adaptability of maize. In this paper, drought sensitive inbred line PH6 WC（6 WC） and drought-resistant inbred line Zheng 58（Z58） were selected as experimental materials. Water control experiment was performed in the pit, and three water treatments（normal irrigation CK, mild drought LD, and moderate drought MD） were set up at ear period, drought treatment would recover to the normal water level after anthesis stage. The ear and tassel development characteristics, anthesis-silking interval（ASI）, and the influence of ear leaf photosynthetic characteristics were measured under different water treatments. The results showed that LD didn′t significantly affect plant height, growth characteristics of ear, relative content of chlorophyll, and maximum photochemical efficiency of PSII in Z58, but significantly decreased the length of ear. MD significantly reduced photosynthetic characteristics, ear length and dry matter accumulation of both ear and tassel in Z58. As for 6 WC, LD inhibited the growth of plant and the development of ear, reduced the length and diameter of ear, length of tassel, distribution ratio of dry matter to ear, the content of chlorophyll a and b, and composite index of photosynthetic performance(PIABS) by 35.3%, 11.8%, 20.6%, 25.0%, 21.1%, 20.0% and 23.8%, respectively. The higher the degree of drought stress was, the greater the influence on the development of 6 WC ear was. In addition, LD and MD resulted in 5 and 9 days′ delay in ASI of 6 WC, respectively; LD and MD resulted in 0 and 3 days′ delay in ASI of Z58, respectively. To sum up, the drought stress at ear stage affected the photosynthesis characteristics of 6 WC and Z58 to different degrees, furtherly the growth and development of ear and tassel of the drought sensitive inbred line was inhibited significantly more than that of the drought-resistant inbred line, which reduced the accumulation and distribution of dry matter to ear.