Preliminary Studies On Some Effects Of Applyinglevel Of N-Fertilizer On Yield Formation And N-Absorbing Character Of Different Types Varieties Of Rice

Preliminary Studies on Some Effects of Applying Level of N桭ertilizer on Yield Formation and N桝bsorbing Character of Different Types Varieties of Rice (Agricultural College. Yangzhou University, Yangzhou, 225009) Postgraduate: Shao Shizhi Supervisor: Prof. Zhang Hongcheng A.Prof. Dai Qigen ABSTRACT With 20 varieties of rice planting widely at different periods in .Tiangsu province as materials, some effects of N-fertilizer on yield formation and N-absorbing characters of I, different types varieties of rice were studied during I 999?000 in the proving farm of agricultural college, Yangzhou University. The main results showed as follows: 1. The spans of total growth period of different varieties of rice were prolonged accordingly along with increase of N-applying amount. The growth periods of high-level treatments of N-fertilizer were prolonged averagely 3 days more than that of low-level treatments in early-ripen mid-season japonica varieties, 3.5 days in mid-ripen mid-season japonica varieties, 3.7 days in late-ripen mid-season japonica varieties, and 5.6 days in early-ripen late-season japonica varieties. 2. N-fertilizer application could increase the leaves number of stem under a certain range of N-applying amount, which was about 5?2.5 Kg/mu in common mid-season japonica varieties, late-season indica varieties, late-season indica hybrid varieties. But applying superabundant N-fertilizer could put up repressive effect on leaves growth of stem except for common late-season japonica varieties by reason of its long growth period. 3. The inter-treatments yield differences were significant without exception among different N-fertilizer application, different varieties, and mutual actions of them. Moreover, average yields of late-season indica hybrid varieties were highest among all types varieties of rice, and higher, in file, than common late-season indica varieties, late-season japonica varieties and mid-season japonica varieties. 4. The effect of N-fertilizer application on the number of panicie per mu was extraordinary significant in all varieties of rice. Under high level of N-fertilizer application, in a general way, the number of panicle per mu was large whereas was small under low level of N-fertilizer application. The numbers of panicles per mu were different significantly among variety types of rice. The descending sequence of numbers of panicles per mu was common late-season japonica varieties> common mid-season japonica varieties> common late-season - 42 - ~Ii;k~ 2001 ~ indica varieties> late-season indica hybrid varieties. 5. Other than different applying level of N-fertilizer treatments, the 1000-grain weights also had significant difference among variety types of rice, among mutual action both variety y pes of rice and N-fertilizer application,. Furthermore, 1000-grain weight of treatments under middle level of N-fertilizer application was larger comparatively than low and high level of N-fertilizer application. It was suggested that 1000-grain weight should increase positively, to certain extent, in according with the applying amount of N-fertilizer, and lessen in condition of...