Interactive Effects Of Nitrogen, Potassium And Water On Wheat And Maize Growth

Interactive effects of multi-nutrients and water play important roles in high yield and high quality crop production. Numerous studies have reported interactive effects of nitrogen and water, whereas little information is available on interactive effects of multi-nutrients and water. In this research, interactive effects of nitrogen, potassium and water on plant growth and potassium uptake of maize seedling were analyzed by a pot experiment, and interactive effects of nitrogen, potassium and water on soil nutrient, nutrient uptake and yield during growth period of winter wheat and summer maize were discussed by field trials. This will give scientific bases to develop efficient use techniques of multi-nutrients and water suitable to main grain crop production regions of dry land in North China. The main results obtained are summarized as follows:1. Interactive effects of nitrogen, potassium and water on maize growth under pot experiment conditionA pot experiment was conducted to study the interactive effects of nitrogen, potassium and water on plant growth and potassium uptake of maize seedling. The results showed that height and dry weight of maize plant under appropriate water condition significantly increased by 7.8% and 13.8% than those under deficit water condition. Significant increases in height and dry weight of maize plant by increasing nitrogen application were found, with respective increase of maize height and dry weight by application of medium nitrogen level being 10.4% and 8.7% under the appropriate water condition, and distinct increasing tendency with increasing nitrogen application under the deficit water condition. Distinct increase in dry weight of maize plant by application of medium and high potassium levels under the deficit water condition was observed. Increasing nitrogen application significantly promoted potassium uptake of maize plant under the appropriate water condition. Whereas potassium uptake of maize plant under the appropriate or deficit water condition remarkably tended to increase with increasing potassium for different nitrogen levels. Increasing nitrogen application significantly decreased root/shoot of maize plant under the appropriate or deficit water condition, and distinctly increased water use efficiency of maize plant. Potassium application generally increased water use efficiency of maize plant under the appropriate or deficit water condition.2. Interactive effects of nitrogen, potassium and water on winter wheat growth under field conditionInteractive effects of nitrogen, potassium and water on soil nutrient, nutrient uptake and yield during growth period of winter wheat were analyzed by field trial. The results showed that significant differences in soil NO₃^--N contents at 0-20 cm depth were found during growth period of winter wheat. Soil NO₃^--N contents were relatively higher at before winter stage, reached a lower level at jointing stage, and slowly rose to a relatively higher level at later growth stages. Distinct effect of water on soil NO₃^--N contents at later growth stages of winter wheat was observed. Soil NO₃^--N contents significantly increased by increasing nitrogen application during growth period of winter wheat. Obvious interactive effects of nitrogen, potassium and water on soil NO₃^--N contents were generally found at main growth stages of winter wheat. Soil available P contents at 0-20 cm depth tended to decreased during growth period of winter wheat, with relatively constant contents from turning green stage to ripening stage, and relatively lower contents at booting stage. Significant effect of water on soil available P contents was found at jointing stage,filling stage and ripening stage of winter wheat. Soil available K contents were the highest at before winter stage, reached a lower level at booting stage, and slowly rose to a relatively higher level at ripening stage during growth period of winter wheat. Soil available K contents increased to some extent by potassium application during growth period of winter wheat. Significant interactive effects of nitrogen and water on soil available K contents were found at booting stage of winter wheat.Significant differences in accumulation rates of N and K during different growth stages of winter wheat were respectively found, with accumulation rates being relatively higher from emergence stage to before winter stage, relatively lower from before winter stage to turning green stage, the highest from jointing stage to booting stage, and the lowest from filling stage to ripening stage. P accumulation rates were relatively lower from emergence stage to before winter stage, reached a higher level from jointing stage to booting stage, and decreased to a relatively lower level from filling stage to ripening stage. Accumulation rates of N, P and K in winter wheat from turning green stage to jointing stage were respectively 19.3%, 21.3% and 20.7% of corresponding total accumulation rates, and from jointing stage to booting stage were respectively 30.7%, 30.9% and 29.9% of corresponding total accumulation rates. Significant increases of N uptake in winter wheat by increasing nitrogen and potassium application were observed, with increases of total N uptake being 6.1%-8.8% and 8.6%-14.0%, respectively. Distinct increases of P and K uptake in winter wheat by potassium application were observed, with respective increases of total P and K uptake being 8.3%-12.5% and 7.0%-11.1%. Nitrogen application improved P and K uptake in winter wheat to some extent. Appropriate rates and proportion of nitrogen and potassium significantly improved uptake of N, P and K in winter wheat. The optimum treatment was N2K2 (medium application rate of N and K) with the highest total uptake of N, P and K during growth period of winter wheat under this field experimental condition, respectively.Significant increases in yields of winter wheat were found by proper irrigation, increasing nitrogen and potassium application, and appropriate rates and proportion of nitrogen and potassium application. The optimum treatment was W1N2K2 (proper irrigation, medium application rates of N and K) with the highest yield of winter wheat under this field experimental condition.3. Interactive effects of nitrogen, potassium and water on summer maize growth under field conditionInteractive effects of nitrogen, potassium and water on soil nutrient, nutrient uptake and grain yield during growth period of summer maize were discussed by field trial. The results showed that significant differences in soil NO₃^--N contents at 0-20 cm depth were found during growth period of summer maize. Soil NO₃^--N contents were relatively higher at seedling stage, reached a lower level at jointing stage, rose to a relatively higher level at teaseling stage, and decreased to the lowest level at ripening stage. Soil NO₃^--N contents significantly increased by increasing nitrogen application during growth period of summer maize. Differences in interactive effects of nitrogen, potassium and water on soil NO3--N contents were generally found at different growth stages of summer maize. Soil available P contents at 0-20 cm depth were relatively higher at seedling stage, reached a relatively lower level from jointing stage to teaseling stage, rose to a relatively higher level at filling stage, and decreased to the lowest level at ripening stage. Insignificant effects or interactive effects of nitrogen, potassium and water on soil available P contents during growth period of summer maize were observed. Soil available K contents at 0-20 cm depth tended to decreased during growth period of summer maize, with the highest contents at seedling stage, and the lowest contents at ripening stage. Soil available K contents by potassium application significantly increased during growth period of summer maize. Differences in interactive effects of nitrogen, potassium and water on soil available K contents were found at different growth stages of summer maize.Significant differences in accumulation rates of N, P and K during different growth stages of summer maize were respectively found, with accumulation rates being much lower at seedling stage, the highest from jointing stage to teaseling stage, and decreased to a relatively lower level from filling stage to ripening stage. Accumulation rates of N, P and K in summer maize from jointing stage to teaseling stage were respectively 47.8%, 54.8% and 67.7% of corresponding total accumulation rates, and from teaseling stage to filling stage were respectively 36.5%, 32.1% and 17.3% of corresponding total accumulation rates. Increasing nitrogen application significantly increased total uptake rates of N, P and K by 15.5%-23.4%, 11.3%-22.2% and 11.4%-20.5%, respectively. Potassium application significantly increased total K uptake rates by 5.7%-12.1%%. The optimum treatment was W1N2K2 (proper irrigation, medium application rates of N and K) with the highest total uptake of N, P and K during growth period of summer maize under this field experimental condition, respectively.Significant increases in yields of summer maize were found by proper irrigation, increasing nitrogen and potassium application, and appropriate rates and proportion of nitrogen and potassium application. The optimum treatment was W1N2K2 (proper irrigation, medium application rates of N and K) with the highest yield of summer maize under this field experimental condition.