摘要
以15N标记的尿素作为叶面施肥和根系后期追肥的N肥品种,分别采用土培与砂培研究小麦与玉米拔节后至灌浆初期不同生育期、不同N、P和K肥叶面配施后作物对叶面N肥利用效率、叶面施用N肥的分配及对全株N、P和K养分状况的影响。无论是小麦还是玉米叶片均能有效地吸收N素并将其迅速转移。玉米拔节期下位叶(第5叶)施肥,植株吸收的15N转移到根部的比例平均为9.0%,而中位叶(第8叶)处理,分配到根系的比例仅为2.4%。叶面施用尿素态氮肥的N在小麦地上部的回收率一般在54.5%~68.9%,在玉米全株体内的回收率可达59.9%~75.3%。随生育期推迟,两种作物叶片吸收N的回收利用率均明显提高。与单施氮肥相比,N,P和K肥配施均有提高氮素回收率和改善作物地上部N素营养的作用,尤以中位叶(第8叶)配施尿素+KH2PO4的效果最佳,表明植物的叶面营养仍应注意平衡供应和适宜的施用时期与施肥部位。叶面大量元素营养不仅改善了所施肥料成分中相应元素的营养状况,同时也促进了对其他两种成分的吸收,并且提高了N、P转运到籽粒中去的比例。玉米吐丝期根系追施的尿素态N有56%积累在籽粒中,而叶面施肥所利用的N分配在籽粒中的比例为70%。
It has been established that plant leaves and other above-ground parts are capable of absorbing chemicals and nutrients. However, there is scarce information regarding translocation and recovery rate of ion uptake via leaves during different growing stages.Urea has generally been found to be the least toxic and most effective form of N for foliar application becasuse of its nonpolar and undisociated characteristics. 15N* labelledurea combined with KCl or KH2PO4 was both applied on selected leaves of corn and wheat at different middle-latter growing periods. The top dressing of 15N杔abelled urea in sand culture of corn at silking stage was also investigated to compare the effects of different foliar and root top dressing on plant growth. The N input in leaves of both crops was remobilized rapidly to other organs. For summer corn, the transferred percentages into roots of 15N input in lower (the fifth leaf) and middle (the eighth leaf)leaf were 9.0% and 2.4%, respectively, at jointing stage. Recovery rate of leaf-input urea*15N in whole corn plant ranged in 59.9%~75.3%, while the rate in above-groundpart of winter wheat was in 54.5%~68.9%. There was very similar tendency for the two crops that the 15N recovery rate taken up via leaves was apparently increased as delay of application period. Compared with urea feeding alone, combined foliar application of urea with KCl or KH2PO4 increased the recovery rate and improved the N nutritional status of whole plants, in which the optimum treatment for corn was foliar feeding of urea plus KH2PO4 to middle leaf. Therefore foliar fertilization should also focus on balance supply, suitable application stage and leaf position. Foliar feeding of N or P and K fertilizer not only improved the corresponding nutrient status in plants, but also stimulated root uptake of the other two nutrients and increased translocation ratio of N and P to grain. The finally accumulated ratios of labelled urea*15N in grains top-dressed via the roots and leaves at silking period were 56% and 70%, respectively.
出处
《土壤学报》
CAS
CSCD
北大核心
2001年第1期67-74,共8页
Acta Pedologica Sinica
基金
国家自然科学基金资助项目!(39470423)