Studies On The Ecophysiological Characteristics Of Maize Under Water Stress

Using a movable rain shelter to keep off precipitation, field experiments on the morphologicaland physiological characteristics of of three cultivars were conducted under different soil moisturetreatments by controlled irrigation. The studies provide scientific bases for economical irrigation, andensure the stable and high yield of maize.The experiments were carried out at the agrometeorological experimental station of the ChineseAcademy of Agricultural Sciences (Beijing) from 2004 to 2005. The maize cultivars selected wereChidan202 (Sidan19), Zhengdan 958, and Ludan 981, based on their different water-consumingcharacteristics. The relative soil moistures for the different treatments were controlled at 40-50% (heavywater stress), 55-65% (mild water stress), and above 75% (control). The treatments ran from thethree-leaf stage till the end of elongation stage in 2004, and till the tasseling stage in 2005.According to the morphological data, the three maize cultivars under mild water stress had similar valuescomparing to that of the control, while under heavy water stress Ludan981 was lower than Chidan202(Sidan19) and Zhengdan 958. From the analysis of morphological characteristics, Chidan 202 (Sidan19)was the most drought-tolerant, while Zhengdan 958 and Ludan 981 were drought-sensitive. The resultsshowed the photosynthetic rate and transpiration rate of Ludan 981 were influenced more heavily bywater stress than the two other cultivars. To a certain extent the water stress increased the water useefficiency of maize. The water use efficiency of drought-tolerant cultivar increased more than that of thedrought-sensitive cultivar in the seedling stage. Water stress had a larger influence on thedrought-sensitive cultivar. In the seedling stage, adequate irrigation for drought-sensitive cultivar wasmore important than for drought-tolerant cultivar.The results showed the photosynthetic rate and transpiration rate of Ludan 981 and Zhengdan 958 wereinfluenced more heavily by water stress than Chidan 202. After rewatering, the photosynthetic rate andtranspiration rate of Ludan 981 under water stress before were higher than that of control. Changes to theefficiency of the PSâ…¡center (F_v/F_m, F_v/F₀) had the same trend as that of the photosynthetic rate underdifferent growth stages. Thus, the chlorophyll fluorescence kinetic technique can quickly and preciselyshow the photosynthetic characteristics of maize under different water stress. Water stress had a largerinfluence on the drought-sensitive cultivar. Adequate irrigation for the drought-sensitive cultivar wasmore important in the early stages than for the drought-tolerant cultivar, in order to assure a higher yield.