| In this study,A set of upland rice genotypes,improved by our laboratory or introduced abroad,as well as mutants and sterile(three-or two-line)(or maintainer)and restorer lines(paddy rice)widely used in production were used.Firstly,upland rice IAPAR9,HD297 and their corresponding mutants idr1-1 and 297-28,were used to identify the response to drought resistance.Secondly,heterosis,combining ability,genetic effects and physiological mechanism of drought resistance were explored using upland rice cultivars as well as its mutant idr1-1 and sterile(or maintainer)or restorer lines(paddy rice)by incomplete diallel cross(NCII)design.Thirdly,heredity base of major agronomic traits were studied according to segregating populations of three combinations,named idrl-1×H14S,idrl-1×TianfengB(TF)and idrl-1x93-11.Lastly,drought resistance and yield potential of F1 hybrid derived from traditional restorer lines and elite sterile lines genetically improved by drought-resistance upland rice(including idrl-1)were evaluated.The conclusions were as following:1.Comprehensive measurement of physiological traits,including morphological development,agronomic traits,water use,and photosynthesis,were conducted and the data were comparatively analyzed.The results indicated that idrl-1 is a dwarf mutant(wild type IAPAR9)with significantly enhanced drought resistance and 297-28 is a mutant(wild type HD297)with high drought-sensitive characters,and even much weaker than the typical paddy rice SN265 in some traits.2.Under WW treatment,the F1 hybrid between upland rice cultivars and maintainer lines showed strong heterosis in different traits.Significant or extremely significant effects were observed in general combining ability(GCA)effects of male,female and the special combining ability(SCA)effects of their interactions.The broad-sense heritability was generally higher and the main stem bottom diameter(MSBD)showed higher narrow-sense heritability.The genotype idrl-1,LB-66F5-10,ZhongjiuB,K17B and Zhenshan97 B had higher GCA and SCA.The F1 hybrid between upland rice cultivars and restorer lines showed over mid-parent heterosis in all traits except fertility,and grain yield per plant(GYPP)was nearly twice of the mid-parent heterosis value.The combination between upland rice and paddy rice displayed significant additive effect except trait days to heading(DH)and tiller number per plant(TNPP)while almost no significant dominant effects were observed between them.The male parent idr1-1,IRAT109 and female parents 93-11,Guanghui207 had higher additive effects and dominance effects in their combinations.3.Under DS treatment,different F1 genotype effects differed significantly by male or female parents and performed obvious heterosis for drought tolerance.Mainly GCA variance existed in them with larger heritability.Male parent idrl-1 and IRAT109 and female parents Shen08S and H14S had stronger GCA and SCA effects.Under WW treatment,genotype effects in all characters demonstrated extreme significant difference,mostly in broad-sense heritability.There were higher GCA effects in female parents PA-2S,H14S and male parent idrl-1,IRAT109 and HD180 and higher SCA effects between them.According to correlation analysis,GYPP was strongly associated with other traits.Also,there were close correlations among some other traits.The influence of aboveground biomass per plant(ABPP),DH,TNPP and setting percentage(SP)on GYPP decrease successively.Four clusters were generated in 40 F1 using cluster analysis,of which combination of male parent idr1-1,IRAT109 and female parent PA-2S,H14S and Guangzhan63S performed better than other combination.4.The drought resistance of two F1 hybrids showed over parent heterosis.The machanism underling in F1 might be as following:higher POD,SOD activity could clean up poisonous substances.On the other hand,abundant osmotic adjustment substances such as proline maintained stable water potential,and stable cell membrance and chlorophyll ensured normal photosynthesis rate.So the viability of F1 plants would not be suppressed by drought stress.5.Most agronomic traits showed multi-modal distribution and only a few showed unimodal or bimodal distribution,suggesting complex inheritance rules.Genetic models for most traits were 2 major gene +poly gene inheritance models and a few were single-gene or poly gene inheritance models.Major gene heritability of segregating generations in some traits was relatively higher than ploygene heritability commonly.Similar major gene heritability was observed among B1,B2 and F2 segregating generations.6.Drought resistance of F1 hybrid between restorer lines and elite progeny of sterile lines improved by drought-resistance upland rice(including idrl-1)had been significantly or extreme significantly improved.The drought resistance of F1 hybrid was stronger than IRAT109,Hanyou3,9311/idrl-1,and slightly lower than idrl-11;yield potential was higher than all controls,indicating that the drought resistance ability of idrl-1 was passed down to the hybrid progeny between idrl-1 and sterile lines,and the drought resistance could be pyramided with the heterosis of paddy rice and even more benefit the heterosis. |
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