不同土壤温度对玉米苗期根系构型的影响

Effect of soil temperature on the root system architecture of maize at seedling stage

为探明不同土壤温度对玉米苗期生长发育的影响,以‘郑单958’为材料,采用新型土壤增温设备进行盆栽试验,在玉米苗期分别设置25.0(CK)、27.5(T_(1))、30.0(T_(2))、32.5(T_(3))和35.0(T_(4))℃5个土壤温度处理,持续处理10 d,测定玉米苗期根系形态、拓扑结构以及各径级根系构型等参数。结果表明,与25.0℃(CK)相比,27.5℃的土壤温度处理可使玉米苗期的根系长度、根系表面积、根系体积、分枝数、根尖数和分形维数均显著增加;随着温度的持续增加,增温对根系的生长发育逐渐产生显著的抑制作用,土壤温度达35.0℃时,上述6个指标均显著降低。土壤温度<30.0℃时,土壤温度的升高导致细根(≤0.5 mm)长度、表面积和体积占总根系的比例均显著升高,在30.0℃的土壤温度下,细根长度、表面积和体积分别占总根系的84.00%、64.79%和31.89%。当土壤温度升至35.0℃时,细根长度、表面积和体积占比均显著降低,而中等根(0.5~1.0 mm)和粗根(>1.0 mm)的占比均显著升高。当土壤温度为27.5℃时,玉米苗期的地上部干重和地下部干重均达到最大值,分别为0.887 8 g和0.460 5 g,此时根冠比也达到最小值,为0.474 7。通过拟合土壤温度与玉米幼苗性状曲线可知,27.3~28.7℃的土壤温度最适于玉米苗期的生长。综上,土壤温度在25.0~30.0℃时,随着土壤温度的升高,玉米幼苗根系随之加长,细根占比增加,植株干重也随之增大,同时保持较低的根冠比;当土壤温度≥30℃,玉米根系生长受限,玉米幼苗细根占比减少,同时根冠比增加。土壤温度达到35℃时,玉米幼苗生长受到严重抑制。

To investigate the impact of different soil temperatures on the growth and development of maize seedlings,a study was conducted using‘Zhengdan 958’as the experimental material,five soil temperatures of 25.0(CK),27.5(T_(1)),30.0(T_(2)),32.5(T_(3))and 35.0(T_(4))℃ were set at the seedling stage of maize,respectively.The increased temperatures lasted for 10 d.The characteristics such as root morphology,topology,and root conformation at each diameter level were determined in maize seedlings.The results showed that compared with the soil temperature of 25.0℃(CK),the soil temperature treatment of 27.5℃ significantly increased the length,surface area,volume,number of branches,number of root tips and fractal dimensions of the maize seedling stage;with the continuous increase of the temperature,the temperature increase gradually produced a significant inhibition of root growth and development,and the above six indexes were significantly reduced when the soil temperature reached 35.0℃.When the soil temperature was<30.0℃,the elevated soil temperature led to a significant increase in the length,surface area and volume of fine roots(≤0.5 mm)as a proportion of the total root system,and at the soil temperature of 30.0℃,the length,surface area and volume of fine roots accounted for 84.00%,64.79% and 31.89% of the total root system,respectively.When the soil temperature increased to 35.0℃,the percentage of fine root length,surface area and volume decreased significantly,while the percentage of medium roots(0.5-1.0 mm)and thick roots(>1.0 mm)increased significantly.At 27.5℃,the shoot dry weight of 0.8878 g and the root dry weight of 0.4605 g at maize seedling reached a significant maximum,and the root-shoot ratio also reached a minimum of 0.4747.By fitting the soil temperature and maize seedling characteristics,it was concluded that the soil temperature of 27.3-28.7℃ was suitable for the growth of maize seedling.In conclusion,when the soil temperature was 25.0-30.0℃,with the increase of soil temperature,the root system of maize seedlings lengthened,the percentage of fine roots increased,and the dry weight of plants increased,while maintaining a low root-shoot ratio;when the soil temperature was≥30v,the growth of maize root system was restricted,and the percentage of fine roots of maize seedlings decreased,while the root-shoot ratio increased.When the soil temperature reached 35.0℃,the growth of maize seedlings was seriously affected.