Research On Fe Deficiency Of Aerobic Rice

Iron deficiency is a common nutrient problem for crop plants on calcareous soils in Northern China. Because of water shortage, aerobic rice system is introduced to these areas and the production area is becoming larger and larger. However iron deficiency of aerobic rice may influence both yield production and food quality at large extent. Consequently, the spreading of aerobic rice might be largely restricted. It is urgent to investigate the possible factors that may induce Fe deficiency problem in aerobic rice. This thesis was mainly focused on the researches on the reasons of Fe deficiency in aerobic rice, which were conducted under both the field and greenhouse conditions. The main results were as follows:(1) Results of field experiment showed: Flooded and aerobic culitivations had significant effect on the growth of aerobic rice at both tillering and physiological mature stage. At physiological mature stage, grain yield, harvest index and Fe harvest index of aerobic rice under aerobic condition were significantly lower than those under flooded conditions. Significant differences in grain yield, harvest index and Fe harvest index were found among different genotypes. Genotype 89B-271-17hun had higher grain harvest index and Fe harvest index than other five genotypes under aerobic conditions.(2) Results of a solution cuture experiment showed: Root exudates of wheat with Fe deficiency application could significantly improve Fe nutrition of aerobic rice. The shoot dry weight, shoot Fe concentration and Fe content of +Fe(OH)₃+ root exudates of wheat with Fe deficiency treatment were higher than that of +Fe(OH)₃ treatment. No difference in iron content of aerobic rice between +Fe(OH)₃+ root exudates of wheat with Fe deficiency and FeEDTA treatment was found.(3) Results of a sand culture experiment showed: Shoot Fe concentration of aerobic rice Han 297 was higher than that of lowland rice Yuefu under the treatments of NH₄⁺-N-Fe and NO₃^--N+Fe. Compared with NO₃^--N, NH₄⁺-N treatment could improve iron nutrition of aerobic rice. Whether Fe was applied or not, dry matter production and Fe concentration of plants under NH₄⁺-N treatment was significantly higher than under N₃^--N treatment. Under +Fe treatment, no difference in iron concentration was found between two NH₄⁺-N concentration levels. Shoot iron concentration of aerobic rice under 0.5 mmol·L^-1 NO₃^--N treatment was significantly higher than that under 2 mmol·L^-1 NO₃^--N treatment. Under -Fe treatment, shoot Fe concentration of aerobic rice under 2 mmol·L^-1 NH₄⁺-N treatment was higher than plants under 0.5 mmol·L^-1 NH₄⁺-N treatment. For NO₃^--N treatment, the results were contrary to what were found. For NH₄⁺-N treatment. Shoot Fe content of aerobic rice under 2 mmol·L^-1 NH₄⁺-N treatment was higher than that under 0.5 mmol·L^-1 NH₄⁺-N. Results of NO₃^--N treatment were contrary to results for NH₄⁺-N treatment. For aerobic rice, iron partition between shoot and root was not affected by different nitrogen forms. However, for lowland rice there was significant effect. Compared with lowland rice, whether Fe was applied or not, shoot dry matter of aerobic rice was higher under differentnitrogen forms.