Using a movable rain shelter to keep off precipitation, field experiments on the morphological and physiological characteristics of the seedling stage of three maize cultivars were conducted under different soil moisture treatments by controlled irrigation. The studies provide scientific bases for economical irrigation, and ensure the stable and high yield of maize.
The experiment was carried out at the agrometeorological experimental station of the Chinese Academy of Agricultural Sciences (Beijing) from May to July, 2004. The maize cultivars selected were Chidan 202, Zhengdan 958, and Ludan 981, based on their different water-consuming characteristics. The relative soil moistures for the different treatments were controlled at 40%～50% (heavy water stress), 55%～65% (mild water stress), and above 75% (control). The treatments ran from the three-leaves stage till the end of seedling stage.
According to the morphological data, the three maize cultivars under mild water stress had similar values to that of the control, while under heavy water stress Ludan981 was lower than Chidan202 and Zhengdan 958. From the analysis of morphological characteristics, Chidan 202 was the most drought-tolerant, while Zhengdan 958 and Ludan 981 were drought-sensitive. The results showed the photosynthetic rate and transpiration rate of Ludan 981 were influenced more heavily by water stress than the two other cultivars. To a certain extent the water stress increased the water use efficiency of maize. The water use efficiency of drought-tolerant cultivar increased more than that of the drought-sensitive cultivar. Water stress had a larger influence on the drought-sensitive cultivar. In the seedling stage, adequate irrigation for drought-sensitive cultivar was more important than for drought-tolerant cultivar.