Abstract:

【Objective】 The objective of this paper was to study the effects of different levels of N and water supply on the accumulation and distribution of dry matter and N in maize leaf and straw-sheath. 【Method】 A pot experiment was therefore conducted during 2008-2009 to study the dry matter and N accumulation and distribution dynamics as affected by different levels of N supply and soil water availability. 【Result】 The results showed that N concentration of leaf and straw-sheath was significantly increased with application of N fertilizer except 11-leaf stage. Adequate water supply significantly enhanced the N concentration of leaf and straw-sheath in N application treatments, however, adequate water supply did not enhance but decreased the N concentration of leaf and straw-sheath in no N application treatments. Whether N were applied or not, the dry matter accumulation of leaf and straw -sheath showed a single-peak curve with maize growing under the condition of adequate water supply, but it showed a continuous increasing trend with growing under the condition of drought stress. The N accumulation of leaf and straw-sheath showed a single-peak curve with growing in all treatments except the one which were treated with not only drought stress but also no N application (in this treatment, no significant differences were observed in N content of leaf and straw -sheath among 3 stages). Whether N and water were supplied sufficiently or not, leaf was the main part of N distribution, but the distribution of dry matter varied with N application and growing stage. When no N fertilizer was applied, the cumulative amount of dry matter in straw-sheath was higher than in leaf from spinning to grain filling stage, however, it was lower than leaf at 11-leaf stage. When N fertilizer was sufficiently supplied, the cumulative amount of dry matter in straw-sheath was always higher than in leaf during the whole growing season.【Conclusion】 The accumulation of dry matter and N in leaf and straw-sheath were asynchronous, and the accumulation curves varied with different levels of water and N supply. Leaf was the main part of N accumulation, but the main part of dry matter accumulation varied with N application and growing stage. N application and irrigation both could significantly increase the dry matter and N content in maize canopy, and the interactive effects between irrigation and N application were significant, in addition, the effect of N application was higher than irrigation in present experiment.

Key words: maize')">maize, water and N supply, N and dry matter accumulation, distribution