河北固城夏玉米比叶面积对水分梯度的响应

Response of specific leaf area of summer maize to water gradient in Hebei Gucheng

基于河北固城农试站2013-2015年夏玉米田间水分控制试验,研究了夏玉米比叶面积(SLA)随发育期的变化趋势,并分主要发育时段探讨了SLA与水分梯度的定量关系。结果表明,从七叶期开始夏玉米SLA随发育进程的推进总体呈下降趋势,七叶期至成熟期SLA变化范围平均为14.6-34.9m^2/kg。尽管干旱胁迫会明显降低夏玉米地上绿叶面积和干重,但却使SLA表现出"补偿性"增大,用于弥补干旱胁迫导致光合产物不足引起的叶片扩张乏力。夏玉米出苗-拔节期、抽雄-成熟期土壤相对湿度(θ)每降低1%,SLA分别上升0.45m^2/kg和0.07m^2/kg,表明出苗-拔节期夏玉米对干旱的"适应"能力更强;而拔节-抽雄期SLA与θ的关系较为复杂,表现为先增大后减小的抛物线型。

Specific leaf area （SLA）, the ratio of green leaf area to its dry weight, is one of the most important parameters of leaf function evaluation, which could reflect resource utilization ability and adaptability to different environments of plants. Recently, many preliminary conclusions have been reported about the variation trend of maize SLA under drought stress, but most of them were qualitative descriptions and lacked quantitative analysis. In this study, based on water-control field experiments in Hebei Gucheng, China from 2013 to 2015, the variation trends of summer maize SLA on major developmental stages were investigated, and the quantitative relationships between SLA and soil moisture on different developmental stages were also established. As the experiment designed, 3 major developmental stages of summer maize （emergence to jointing, jointing to tasseling, tasseling to maturity）, as well as[（emergence to jointing） ＋ （jointing to tasseling）],[（emergence to jointing） ＋ （tasseling to maturity）], and[（jointing to tasseling） ＋ （tasseling to maturity）], were all water controlled in turn. The experiment was set with 4 water-control treatments and 1 contrast treatment, in which the soil relative moisture θ was ≤ 40% （T1）, 40%-60% （T2）, 60%-80% （T3）, 〉80% （T4）, and natural precipitation （T5）, respectively. Results showed that the summer maize SLA presented a declining trend during the entire growing season, with an averaged variation range of 14.6-34.9m2/kg. Specifically, the SLA reached maximum value at seven-leaf stage （34.9m2/kg）, declined rapidly at jointing stage （23.4m2/kg）, decreased slightly at the tasseling stage （18.1-18.8m2/kg）, and was the lowest at the maturity stage with an average of 14.6m2/kg. Experimental data showed that drought stress could significantly decrease the leaf area and dry weight of summer maize, but the SLA showed a ＂compensatory＂ larger value in order to compensate for the leaf expansion fatigue caused by insufficient photosynthates. The summer maize SLA had a significant linear negative correlation with soil moisture from the emergence to jointing and tasseling to maturity stages, with increase of 0.45m2/kg （emergence to jointing stage） and 0.07m2/kg （tasseling to maturity stage） when the soil relative moisture decreased by 1%, indicating that the summer maize had more adaptation to drought during emergence to jointing stage. However, the relationship between SLA and soil moisture on the jointing to tasseling stage was more complex; it first increased and then decreased with a parabola shape.