Zinc Partitioning And Accumulation In Rice (Oryza Sativa L.) And Genotype Differences

Rice is one of the major food crops for human,Zn content,distribution and biological activity of rice is essential for rice-eating humans zinc nutrition.However, the systems of Zn partitioning and accumulation is not perfect.In this study,different rice genotypes with different Zn contents were used.This research focus on rice agronomic characteristics,yield,quilty,zinc partitioning and accumulation to different Zn2+ activities.The results were as follows:1.The study showed that under deficiency condition pZn²⁺ 11.4,zinc-efficient genotype IR8192 could more effectively increase dry matter of root,to increase root length and root absorbing area,so as to more effectively deal with the low zinc stress than zinc-inefficient genotype IR26.2.Chlorophyll content,intercellular CO₂ concentration,photosynthetic rate were increased with the increasing Zn²⁺ activities.Extremely zinc deficiency made transpiration rate of seedling rice significantly decreased,when Zn²⁺ activities higher than pZn²⁺ 11.0,the further increase of Zn²⁺ activities could not make transpiration rate change significantly.Stomatal conductance of all genotypes were maximum at pZn²⁺ 9.7.3.In the seedling and tillering stages,acetic acid-extractable(heavy metal phosphates) zinc predominated in the leaves;jointing to heading stages, ethanol-extractable(alcohol-soluble proteins,amino acids,et al) zinc predominated in the leaves.4.Different Zn²⁺ activities had a significant effect on rice yield per plant through effective panicles per plant,spikelet numbers per panicles,seed setting rate, 1000-grain weight.Effective panicles per plant was mostly affected,spikelet numbers per panicles less,the effect on seed setting rate was relatively little, but it was differed between BY and Z921.5.The zinc content was increased in every organs with the decreasing of Zn²⁺ activity,and there were differences between genotypes,also organs.Zn first accumulated to vegetative organs under sufficient Zn supply;Zn first accumulated to grains under deficient Zn supply.Judging form the distribution of grain zinc,when Zn²⁺ activity lower than pZn²⁺ 10.3,the zinc content in brown rice was higher than that in grain hull,but with the Zn²⁺ activity increasing,the zinc content in grain hull became higher.The zinc ratio of brown rice to milled rice was always between 0.79 to 0.90,the ratio was the smallest when pZn²⁺ 9.7.The grain zinc content in BY was much higher than that in Z921 at any Zn2+ activity.6.The seeds germination rate,germination index and vigor index increased with the Zn content of rice seeds increasing.The seedling height and root length of the 8th rice seedling increased with the Zn content of rice seeds increasing. The seedling chlorophyll content increased significantly with the Zn content of rice seeds increasing.7.Seedling protein and MDA content was negatively correlated with Zn content of rice seeds;soluble sugar and soluble protein was positively correlated with Zn content of rice seeds.APX,POD,CAT activity increased certainly with the Zn content of rice seeds increasing,in order to resist the reactive oxygen species,scavenging free radicals and other harmful substances,and better to protect cells from damage.So,increasing Zn content of rice seeds was conducive to enhancing the seedling osmotic adjustment ability in order to improve their ability to cope with stress.