苜蓿、玉米根系提水作用与耐旱性的关系——植物根系提水作用机理研究Ⅱ

The Relationship of Hydraulic Lift in Alfalfa and Maize and Their Drought Resistance Study on Mechanism of Hydraulic Lift in Root System of Plant(Ⅱ)

为了揭示植物根系提水作用与抗旱性的关系,选用抗旱性较强的苜蓿和2个旱作型玉米杂交种为材料,利用中子水分仪在大田条件下研究了其蒸腾速率和根系特性与根系提水作用大小及其抗旱性强弱的关系。结果表明:3种供试材料的蒸腾速率与其单位叶面积气孔数和气孔开度呈明显正相关,相关系数(r)分别为0.958 7和0.999 9,而与单株每夜的表观根系提水量(Qm)则呈弱负相关,r仅为-0.490 0,表明较低的蒸腾速率促进根系提水作用。2种玉米根系特性测定相比,耐旱性较强的豫玉22玉米无论是上层干燥土壤中根系的体积、鲜重、干重和根数,还是下层湿润土壤中根系的体积和干重都明显大于中单二号,但每夜单株的Qm却仅为后者的63.34%,表明在一定条件下,较为发达的根系和相对较低的根系提水作用,是植物具有较强耐旱性的一个重要原因。

A drought-resistant alfalfa variety and two high-yield maize varieties with different drought-resistance ability were investigated using Neutron probe on the relationship between transpiration/hydraulic lift and the capacity of drought resistance and between the characteristics of root system and hydraulic lift and the capacity of drought resistance. The results indicate that the transpiration rate had distinct positive correlation with the number and opening degree of stoma on the unit leaf area, correlation coefficients were 0. 958 7 and 0. 999 9, respectively. However, the transpiration rate was weakly and negatively correlated to the apparent lifted quantity each night each plant （Qm） and the correlation coefficient was only -0. 490 0. It showed that the low transpiration rate could improve the hydraulic lift in root. The comparison between root system characteristics of two maize varieties showed that Yuyu No. 22 had bigger the root volume, wet weight, dry weight, and the number of root in the shallow or deep soil than Zhongdan No. 2, but had only 63.34% of Zhongdan No. 2 in the amount of actual water hydraulic lift in root one night per plant. Those results indicated the strong root and the low hydraulic lift in root was one of the reasons for strongerdrought-resistance.