Tillering Characteristics and Its Relationships with Population Productivity of Super Rice under Different Cultivation Methods in Rice-Wheat Cropping Areas

To explore tillering characteristics and its relationships with population productivity of rice under different cultivation methods in the rice-wheat cropping system in the lower Yangtze River,we compared the characteristics of rice tillering and panicle formation and its productivity and contribution to yield with two super rice cultivars Huaidao 9 and Xudao 3 by using three cultivation methods,precision artificial transplanting with dry nursery middle and strong seedlings,mechanical transplanting with small seedlings and direct seeding.Results showed that rice yields by using different cultivation methods were significantly different,artificial transplanting rice was the highest,while direct seeding rice was the lowest.The great contribution to yields of mechanical transplanting rice and direct seeding rice were mainly from main stem and primary tillers group,in particular for the direct seeding rice,the proportion of stem yield was up to 27.5%,that of secondary tillers group only about 5%. However,for artificial transplanting rice the stem yield proportion was small(16.7%),yield of secondary tillers group accounted for nearly 20%. The proportion of primary tillers group yield was relatively stable among the different cultivation methods and it ranged from 65.84% to 67.09%. The number of tiller leaf position of artificial transplanting rice was more,earbearing tiller percentage was higher and panicle number per plant was more.The primary tillers group emerged from leaf 1 to leaf 10 on main stem,among them the tillers from leaf 5 to leaf 8 had higher emerging rate and more panicles,secondary tillers group emerged and earbeared mainly in 1/5,1/6,and 1/7.Tillers of mechanical transplanting rice had a more concentrated emergence,the primary tillers group emerged from leaf 3 to leaf 7 on main stem,among them leaves 4 to 7 were the superior positions for tiller emerging and panicle formation,secondary tillers group emerged mainly in 1/4,2/4,1/5,but earbeared mainly in 1/4.The primary tillers group of direct seeding rice emerged from leaf 1 to leaf 5 on main stem,among them the leaf positions of 1 to 4 had higher rate of tiller emerging and panicle formation,secondary tillers emerged more,but earbeared only in 1/1,2/1,1/2,with a very low earbearing percentage.These three cultivation methods did not give tillering three times and more than three times.The tillers group of main stem and superior leaf positions in each cultivation method had higher population productivity and better panicle traits,made great contributions to the yield,and more than 85% of the yield came from these stems and tillers.The results suggested that the tillering and panicle formation law by different cultivation methods is different.It is indicated that increasing percentage of earbearing tiller and panicle number per plant and playing regulation fully of tillers group will improve the yield.In rice production,we should enhance the superior leaf position tillers' emergence and flowering frequency,inhibit invalid tillers,improve the population quali-ty,explore the way to increase yield potential of the superior leaf position by using the consequentially supporting management measures and through the precise regulation of density,fertilizer application and irrigation based on the actual various cultivation methods,consequently,achieve the target of high yield and efficient production under different cultivation methods.