| Studies on agronomic traits and genetic effect of rice (Oryza sative L.) genotype with Zn-rich grainsThere is an extensive difference in Zn-content in grain among different rice genotypes. The method is reasonable that human nutrition of Zn can be improved by rice breeding in selecting and cultivating genotypes rich in Zn. Much attention was not paid to this topic but during these past years a few researches have been done, but are few studies about the mechanism of Zn accumulation in rice grain and the bioavailability of Zn. The indication of selection and genetic characteristics are seldomly studied too. In this study, using different rice genotypes with different Zn-content in grain, under solution culture with different Zn concentration to investigate the effect on agronomic characteristics; to realize the genetic characeristic of Zn-content in grain through diallel cross method; and to compare the phytate-content in grain which influenced the bioavailability of Zn in different rice genotypes.The genetic analysis about phytate-content in grain was also done. The main results are summarized as follows:1. There is significant genotypic difference in variety of root shape under different Zn concentration. When Zn cone, changed from 40 umol/L to 10 u mol/L, the response of Zn-poor grain cultivars Zhe921 promoted root number faster and larger than the response of Zn-rich grain cultivars BY. At the same time, BY decreased significantly in the root length ,but Zhe921 increase significantly. The variation in the ratio of root dry weight to shoot dry weight(RDW/SDW) is different between BY and Zhe921 when Zn cone, changed from 40 u mol/L to 10umol/L. RDW/SDW of Zhe921 increased significantly,but RDW/SDW of BY decreased at first and increased later.Under Zn cone. 10umol/L, the Zn-content of BY's seedling is higher than Zhe921's seedling above 20%. All the above show that Zn-rich grain cultivars had higher efficiency to absorb Zn than Zn-poor grain cultivars. Under lower Zn cone., Zn-rich grain cultivars had more effective physiological mechanisms of absorbing Zn other than the change of root shape.2. The plant height and dry weight increased when the Zn cone, was reduced. They increased at early days, then decreased quickly. When Zn cone, changed from 40 u mol/L to 10u mol/L, the effect was maintained a longer period. But the Zn-rich genotype and the Zn-poor genotype had little difference.3. There was little potential to enhance the Zn-content in unpolished rice and polished rice of Zn-rich grain cultivars, but Zn-poor grain cultivars had much potential. This indicates that there is a mechanism of regulating Zn accumulation in grain, which makes Zn-content to be maintained in definite level.4. The Zn-content in grain of rice is influenced by environment , apart from controlled by genetic factor. Environment and genotype have obvious interaction, which make same rice genotype having large variation with. Zn-content in grain. But the trait of high Zn-content can be expressed at any environment.5. The dry matter accumulation of grain was increased through spraying zinc fertilization on rice leaf, which made the 1000-gram weight enhanced. But ,there are different effect on different rice genotypes.6. In grain, the content of macroelement and microelement can be controlled by different genetic mode. The content of macroelement in grain can be controlled more by genetic effect. The content of microelement in grain can be controlled less by genetic effect. Zn is microelement, but its phenotype variance is similar to macroelement. Most variance came from genetic factor. The effect of environment was not dominant. Zn-content in grain was mainly controlled by non-additive.7. The phytate content in rice grain had significant variance of genotype, which was controlled by genetic system of maternal plant and seed, which among them, seed direct dominance variance is the most important effect,next is maternal dominance effect and maternal additive effect. |
PDF Full Text Request