Responses Of Growth, Yield, Quality Components And Nitrogen Use Efficiency To Coated Urea Application In Three Rice Cultivars

In order to provide valuable information for rational use of slow-release/controlled release fertilizers in rice production, a field experiment was conducted in2009-2010to investigate the responses of growth, grain yield, quality components and nitrogen use efficiency to the application of controlled coated urea fertilizers (L-type and S-type, Made in Japan), with three rice cultivars, Yangjing4038(Japonica), Yangdao6(Indica) and Yangliangyou6(Hybrid), as materials. Following results were obtained:1. The order for numbers of effective tillers and panicles was:Yangjing4038> Yangliangyou6> Yangdao6. The maximum tillers and productive panicles under in the treatment of L-type coated urea were higher than those of S-type coated urea, which indicated N released more quickly in early growth period from L-type urea than from S-type urea.2. The leaf area index (LAI) responded to coated urea differently with cultivars. Compared with S-type urea, L-type coated urea and conventional urea increased LAI of Yangjing4038and Yangdao6from heading to maturity. LAI of Yangliangyou6at15d after heading was higher in L-type coated Urea and no obvious difference of LAI between fertilizer treatments was found in maturity.3. Leaf SPAD values after heading in Yangjing4038and Yangdao6were higher in treatment with S-type coated urea than those with S type and conventional urea. SPAD value of Yangliangyou6did not apparently respond to urea type, but a higher SPAD value was observed at15d after heading in S-type urea treatment.4. Root bleeding sap intensity of three cultivars during grain filling were enhanced by coated urea. In this aspect, S-type coated urea showed better effect than L-type.5. Coated urea increased dry matter accumulation in Yangjing4038and Yangdao6, and L-type urea was better to Yangjing4038while S-type was better to Yangdao6in this point. Dry matter accumulation of Yangliangyou6did not respond to urea type.6. The response of grain yield to urea type varied with cultivars. Compared with conventional urea, L-type and S-type coated urea increased grain yield of Yangdao6. Grain yield of Yangjing4038treated with L-type was higher than those with S-type and conventional urea. Urea type had no effect on grain yield of Yangliangyou6.7. Rice quality components responded to urea type. Urea type showed no effect on percentages of brown rice and polished rice of Yangjing4038and Yangdao6, but those of Yangliangyou6could be elevated by S-type urea. Head rice percentage of Yangjing4038did not vary with urea type, but that of Yangdao6and Yangliangyou6increased under coated urea treatments. In this study, rice chalkiness of all the cultivars increased in coated urea treatments. Coated urea increased protein content of all cultivars. Amylose content of Yangliangyou6decreased in S-type urea treatment, but urea type did not affect amylose content of other two cultivars. Gel consistency of Yangdao6and Yangjing4038was lower under coated urea treatments, while that of Yangliangyou6did not respond to urea type.8. N recovery (%) was generally elevated by coated urea in this study, but different cultivars responded in different ways. Yangjing4038and Yangliangyou6applied with S-type urea showed higher N recovery while Yangdao6had higher N recovery in L-type treatment.9. Compared with conventional urea, more NH4+-N in coated urea treatments remained in soil after rice harvest.