摘要：
The study was conducted to investigate the effects of applying different concentrations of the macronutrients K+,Ca2+,and Mg2+on the responses of contrasting rice(Oryza sativa L.)genotypes under salt stress.A solution culture experiment was conducted in a phytotron at the International Rice Research Institute(IRRI),under controlled temperature and humidity and natural sunlight.When subjected to salt stress of 100 mmol L-1 using NaCl,the salt tolerant genotypes FL478 and IR651,accumulated less Na+and maintained lower ratios of Na+/K+,Na+/Ca2+,and Na+/Mg2+than the sensitive genotypes IR29 and Azucena.These tolerant genotypes also had higher concentrations of K+in their shoots and greater root and shoot biomass and green leaf area.Tolerant genotypes also maintained much lower concentration of Na+and lower and more favorable ratios of Na+/K+,Na+/Ca2+,and Na+/Mg2+in their active and developing tissues.Salt tolerance and shoot and root growth of both tolerant and sensitive genotypes were enhanced considerably when higher concentrations of Ca2+and Mg2+were applied in culture solution.The concentration of Na+and the ratios of Na+/K+,Na+/Ca2+,and Na+/Mg2+ in shoots also declined significantly.The beneficial effects of higher calcium were greater than that of magnesium and application of higher concentration of K+seems to have minor effects.Responses to salinity in rice can therefore be considerably enhanced through proper nutrient management,by increasing the concentrations of nutrient elements that have favorable effects such as Ca2+and Mg2+.Calcium is particularly more effective than both magnesium and potassium,and can be applied at relatively larger quantities in salt affected soils.
摘要：
In order to determine the suitable NPK account for this eugenic winter rape: Xiangzayou763, field and pot experiment was set up during the year 2008-2010 and optimized the ratio and dose of NPK by the laboratory test method during harvest period, in which the yield in all treatments and economic benefits would be investigated. The result shows that with NPK ratio at (N:P2O5:K2O) 1:0.50:0.50, fertilizers N, P2O5, K2O supply at 180 kg/hm(2), 90 kg/hm(2), 90 kg/hm(2), it is the best suitable way for NPK usage, with which winter rape takes the largest oilseed yield, reaching 2231.13 kg/hm(2). On the yield component factors of correlation, the maximum was found between single stub cape fruit number and output, followed by Seed numbers per pod, mass of 1000 grains respectively; and the nitrogen had the maximal impact on the yield of winter oilseed rape, followed by phosphorus and potassium. According to the above ratio, the grain output value was 9816.97 Yuan/hm(2), in which only 1641.23 Yuan/hm(2) for fertilizer investment, the fertilized efficiency value reached 6741.34 Yuan/hm(2), then the VCR reached 4.11.
关键词：
Later growth period;nitrogen loss in plant;nitrogen redistribution;nitrogen-use efficiency;oilseed rape
摘要：
To determine the relationship between nitrogen (N) redistribution of oilseed rape (Brassica napus L.) varieties and N-use efficiency during later growth stages, the differences in N-use efficiency between two varieties (X-36 and X-50) were studied using the 15N labeling method with sand culture under complete nutrient solution conditions. Results showed that X-36 had greater grain yield not because of greater N uptake but because of greater grain yield per unit N in the plant and N-harvesting index. The average proportion of N in the two varieties that was redistributed from the vegetative organs to the grain was 65.1%. The redistribution amount and the proportion of N absorbed at the stem elongation stage and redistributed into the grain of two varieties were the greatest; the least were amounts absorbed at the siliquing stage. The high-N-use-efficiency variety (X-36), when compared with the low-N-use-efficiency variety (X-50), had slower redistribution speed of N before the siliquing stage, which then became faster after the siliquing stage. The amount of N redistributed to the grains and its proportion were larger, whereas those toward the silique husk were smaller. The amount of N loss from the plant and its proportion were smaller, and the velocity of N loss was also slower. This explains why varieties with high N efficiency have high N-harvesting index. At the later growth stages, N redistribution in the vegetative organs will significantly affect N-use efficiency.
