Developing Of Intersubspecific Two-line Japonica Hybrids And Researches On Cultivation And Seed Production Technology

Rice is one of the main food crops in Xinyang City, Henan Province. 90% of areawas indica hybrid rice in 0.4 million hectare a year. Developing intersubspecific japonicahybrid rice with similar yield as indica hybrid rice has been impotant for increasing thebenefit of rice farmers because of the lower of indica rice. The aim of this study was todevelop japonica hybrid rice through crossing tipical conventional japonica varieties withwide compatibility photoperid-thermo-sensitive genic male sterile line. Twointersubspecific japonica hybrid rice combinations were developed in past several years.The japonica characteristics, yield heterosis, trait characteristics, high yield cultivationand seed production techniques were investigated. The main results were as follows:Xin-za-jing No 1 and Liangyou Peijing were developed by using typicalconventional japonica varieties Yujing 3 and 94205 as male parents crossing directly withPeiai64S, a wide compatibility photo-thermo-sensitive genic male-sterile line. Xin-za-jingNo 1 had 15% of yield increase comparing with Yu-jing No 3 (CK) in Henan Provinceyield trials. Liangyou Peijing had 20% of yield increase comparing with Zhong-zuo93(CK) in Henan province and national yield trials and farmer's production tests. Theyields were similar as medium indica hybrid rice combinations (â…¡you 838) with betterrice quality and strong resistance. The two combinations have become major extendedvarieties in southern area in Henan as "Japonica replacing indica rice reform".Cultivation investigation was extremely necessary because of complicated geneticbackgrounds and unusual performance in two combinations. A six-factor approximateoptimal mixed design(628 design) were adopted to conduct multi-factor comprehensivecultivation of Xin-za-jing No 1. The six-factor quadratic regression model of yield wasestablished. By model analysis, simulation and optimization, specific agronomicmeasures with high yield and low fertilizer input were obtained as follows(in 1hm~2):211-221 kg of seed rate, 810000-840000 transplanting seedlings. Reviving fertilizer,tillering fertilizer, Spikelet-developing Fertilizer were 59-63kg, 65-71kg,26-29kg urearespectively as well as 108-115kg potassium chloride. Total nitrogen (including 500kgammonium bicarbonate as base fertilizer ) are 154-160kg (10.5kg/666.7m2).Based on five year (1997-2001) variety experimental data, the relationship betweenyield and 11 economic traits of Xin-za-jing No 1 were analyzed by multi-level stepwise regression analysis and path analysis. The optimal yield regression equation with highdegree of fit and three multiple regression sub-equations were established. High yieldpotential and economic traits of Xin-za-jing No 1 were understood. Research showed thatthe most important key factor is to keep the maximum number of tillers in Xinzajing Onesuper high-yielding cultivation, which calls for early application of tiller fertilizer or less(mainly relying on adequate base fertilizer), early drainage of paddy fields to stronglyinhibit excessive invalid tillerings.The five technical measures of seed production in the yield of 2.25-3.00t/ha forXin-za-jing No 1 and Liangyou Peijing were put forward as follows: deciding sowingtime to ensure double security; narrowing row ratio and transplanting adequate seedlings;controlling nitrogen fertilizer application to prevent female parent from overgrowth;Early and heavy spraying Ga3 to increase the rate of outcrossing setting; and adoptingcomprehensive measures to effectively control rice kemel smut.