增施磷肥对重度盐碱地食葵生长及土壤微生物区系的影响

Effect of phosphorus application rates on sunflower growth and soil microflora in severe saline land

采用大田筒栽试验,设置4个施磷(P2O5)水平:CK(不施磷)、P4(60 kg·hm^(-2))、P8(120 kg·hm^(-2))、P12(180 kg·hm^(-2)),研究了重度盐碱地施磷对食葵叶片保护酶活性、植株干物质积累、磷吸收以及施磷后土壤微生物区系变化特征的影响。结果表明:增施磷显著提高了食葵叶片保护酶活性,食葵叶片超氧化物歧化酶(SOD)与过氧化氢酶(CAT)活性在施磷达到P4水平即显著提高,且达到P12水平又出现显著增加;而过氧化物酶(POD)活性在施磷量达到P12水平才显著增加。叶片丙二醛(MDA)含量与SOD活性保持相对同步,在施磷量P4、P8水平并没有显著降低,直至达P12水平才显著下降,比CK降低31.40%。食葵叶片、籽粒、根干重及根冠比在施磷量达到P12水平时也显著高于其他处理。食葵籽粒、根系磷积累量均随着施磷量增加显著提高,且各施磷处理食葵地上部、根系含磷量也均显著高于CK,但P12与P8处理差异不显著,另外施磷有利于食葵吸收的磷素由根系向地上部转移运输。增施磷通过调控根系生长以及改善微环境显著增加了土壤细菌、放线菌、真菌等可培养微生物数量,且以P12处理增加最多。食葵盛花期和成熟期也均以P12处理优势菌群种类最丰富,其中盛花期P12处理有数量较多的节杆菌属(Arthrobacter),在食葵收获后则含有考克氏菌属(Kocuria)、葡萄球菌属(Staphylococcus)和噬几丁质菌属(Chitinophaga)。综合比较来看,河套灌区重度盐碱地施磷180 kg·hm^(-2)可以显著增加食葵叶片保护酶活性,促进食葵生长及磷吸收积累,提高食葵抗性,同时有利于土壤微生物多样性增加。

We conducted barrel planting experiment to investigate the leaf protective enzymatic activities, dry matter accumulation, P uptake of sunflower and the variation characteristics of microflora in soils with different levels of P supply. Four P treatments was implemented including CK（0 kg·hm（-2））, P4（60 kg·hm（-2））, P8（120 kg·hm（-2））and P12（180 kg·hm（-2））. The results showed that applying P significantly improved sunflower leaf protective enzymatic activities, and the leaf SOD and CAT activities were significantly increased when the P application reached P4 level, further increase at P12 level, but POD activity was significantly increased only when reached P12 level. The leaf MDA content kept pace with SOD activity and it significantly decreased by 31.40% compared with CK only at P12 level. The leaves, seed, root dry matter weight and the roots/shoots ratio of sunflower were significantly higher under P12 than that under other treatments. Meanwhile, the P accumulation in seed and root increased with P supply, also the P contents at shoot and root under all P treatments were significantly higher than that of CK, but no significant differences occurred between P12 and P8. Furthermore,P application was conductive to the P transportation from roots to overground parts. We also found P application significantly increased the quantity of cultivable microorganisms by regulating sunflower root system and improving soil microenvironment, and P12 treatment presented the greatest increase in bacteria, actinomyces and fungus quantity and also showed the most abundant species of dominant microflora with a large number of Arthrobacter at flowering stage and Kocuria, Staphylococcus and Chitinophaga after sunflower harvest.Compared comprehensively, applying P with 180 kg·hm（-2）in severe saline land in Hetao Irrigation District can significantly increased the leaf protective enzymatic activities, promoted sunflower growth and P uptake and thus strengthened sunflower stress resistance, in the meantime increased the soil microbial diversity.