Effects Of Postanthesis Soil Water Status And Nitrogen On Yield And Quality Formation In Strong Gluten Wheat

From 2004 to 2006, this research was carried out under rainout shelter with strong gluten variety Jimai20 under different postanthesis soil water status and nitrogen level. The effects of soli water status and nitrogen on wheat yield and quality were studied under 3 nitrogen fertilizer amounts (150 kg/hm~2,225 kg/hm~2 and 300kg/hm~2) and 3 soil water status (40—50%,60—70% and 80—90%), to find the optimal nitrogen fertilizer and soil water status for high field and best quality. The main results were as follows:1 It showed that too low or high a content of soil water lead to planting prematurely senile, leaf area index , accumulation of dry matter, the total amounts and mobilization rate of pre-anthesis stored assimilates from vegetative organs decreased, population transmittance increased, grain filling cut down, grain weight declined. Under water stress nitrogen promoted growth of wheat. But grain wheat decreased when oversupplying nitrogen fertilizer more than 300kg/hm2.2 Compared 60—70% of postanthesis soil water status, 40—50% and 80—90% increased SPAD, photosynthetic rate(Pn) and the activity of protective enzymes ( POD, CAT, SOD), alleviated leaf membrane lipid peroxidation, decreased MDA and Pro content, delayed the senescence of the flag leaf. Under 40—50% and 80—90% of postanthesis soil water status nitrogen increased SPAD and Pn and delayed the senescence of the flag leaf.3 Under 40—50% and 80—90% of postanthesis soil water status, SPS, SS, SSS and GBSS activity of flag lea, soluble sugar content of leaf and starch content and accumulation decreased. Under 40—50% and 80—90% of postanthesis soil water status nitrogen increased SPS and SS activity, increased soluble sugar and sucrose content at mid-and later-growth stages. Below 225kg nitrogen per hectare amount, starch components were improved with increasing supply of nitrogen fertilizer.4 Under 40—50% and 80—90% of postanthesis soil water status, NR and GS activity of flag leaf and grain decreased, synthesis and translocation of free amino acid in leaf and sheath & stem decreased, and protein accumulation decreased. Soil water stress decreased the amounts and remobilization rate of pre-anthesis stored nitrogen from nutrition organs to kernels, decreased nitrogen accumulation of grain. Below 300kg nitrogen per hectare amount, synthesis and translocation of nitrogen, nitrogen accumulation of grain were improved through increasing supply of nitrogen. Below 225kg nitrogen per hectare amount, nitrogen translation from nutrition organs to kernels and nitrogen content of grain improved with increasing supply nitrogen fertilizer.5 Under 40—50% and 80—90% of postanthesis soil water status, grain, protein and starch field, ratio of amylose contents to amylopectin contents of wheat grain decreased. Below 225kg nitrogen per hectare amount, grain yield, protein content, ratio of glutenin contents to gliadin contents, ratio of amylose contents to amylopectin contents improved with increasing supply nitrogen fertilizer. However, grain field, starch content and ratio of glutenin contents to gliadin content decreased with application more than 300kg per hectare amount of nitrogen fertilizer. Compared 40—50% and 80—90% of soil water status and 150kg and 300kg per hectare amount of nitrogen fertilizer, 60—70% or 225kg increased grain test weight and flour extraction, peak viscosity, break down, final viscosity and set back of dough. Protein content, content of wet gluten, zeleny sekimentility, grain falling, elasitic force and paste biceps of dough increased with decreasing soil water status or increasing nitrogen fertilizer, but ductility of dough decreased.In conclusion, effects of soil water status and nitrogen on photosynthetic characteristics and senescence, carbon and nitrogen metabolism, activity of their enzymes and assimilate translocation and remobilization are the major reason for the differences in grain field and quality of strong gluten wheat. The best nitrogen and soil water status applied amount was 225kg/hm2 and 60—70% to get high yield and high quality.