施钾方式对高产春玉米根系分布及其活力的影响

目的]探讨施钾方式(一次性施入和钾肥后移)对高产春玉米根系特性的影响,为高产春玉米钾素养分调控提供理论依据。方法]以金山27玉米为供试品种,2个施钾水平(K2O 150和300kg/hm2)及施钾后移处理下,测定不同生育时期各土层根系干物质重、根系活力及其酶活性,成熟期测定根条数、根幅。结果]300kg/hm2施钾水平与150kg/hm2施钾水平相比,各土层根系干重增加,尤以吐丝前0—20cm土层为根干重增加幅度最大,20—60cm土层根干重占总干重比例减小,尤以乳熟期为甚;各土层根条数、最大根幅增加,最大根幅下移;各生育时期各土层根系活力、超氧化物歧化酶(SOD)活性和过氧化物酶(POD)活性随施钾量增加而增加,丙二醛(MDA)含量下降。相同施钾水平下,施钾后移各生育时期0—60cm各土层根系干重减小;0—20cm土层根干重占总干重比例增加;最大根幅、根条数及最大根幅深度均减少,且随土层深度增加差异增大;各土层根系活力、SOD酶活性和POD酶活性降低,MAD含量增加。结论]300kg/hm2施钾量较150kg/hm2施钾量促进玉米根系生长,且延缓根系衰老,尤其可促进深层根系的生长;同一施钾水平下,施钾后移则促进作用不明显,甚至降低了根系的干重。

Effects of Potassium Fertilization Methods on Root Distribution and Root Vitality of a High-Yield Spring Maize

Objective] To provide some bases for nutrient regulation of high yield maize, the effects of potassium fertilization on root vitality of a high yield spring maize were investigated. Potassium fertilization had application level treatment with two levels of 150 and 300 kg/hm² and application method treatment with levels of once-and-base fertilizer and postponed application.Methods] A maize cultivar, Jinshan 27, was used as the test material. Its dry root weight, root vigor, activities of superoxide dismutase(SOD) and peroxidase(POD), and malondialdehyde(MDA) content were measured at each stage; root number and root width were measured at mature stage.Results] Root dry weight at 300 kg/hm² application level was greater than that at 150 kg/hm², especially it was obvious in 0-20 cm layer before silking stage. The percentage of root weight at 20-60 cm was contrary, especially in milking stage. Root number increased at high application level, and also the biggest root width increased and proliferated deeper. At high application level, vigor, SOD and POD activities of root in all growth period increased, while MDA content decreased. Root weight of postponed fertilization at 0-40 cm soil layer was less than that of once-and-base fertilization method; while, the percentage of root weight at 0-20 cm soil layer was relatively great. Root number, the biggest root width and the layer with the biggest root width of postponed application was lower than that of the once-and base application method, and the differences of these indices between the two methods increased with the increase of soil depth. Root vigor and activities of SOD and POD of postponed application decreased; MDA content increased.Conclusion] Once-and-base K application could improve the root growth of maize and especially the proliferation at deep layer was promoted; It also delayed the senescence of root. These effects were not observed, and moreover the contrary effects it were for postponed application.