| Owning to fast development of industry and the widespread uses of herbicides and pesticides with copper (Cu), the area of Cu-contaminated soil is extending every year, and soil Cu concentrations in agricultural soil is increasing as well. As a result, there is a growing public concern about the effect of soil Cu stress on rice growth and development. In order to elucidate the differences among indica rice cultivars in yield formation responses to Cu stress and its causes, a pot experiment was conducted on six indica rice cultivars under two levels of soil Cu concentration (51.74 mg·kg-1, CK; 400 mg·kg-1, Cu treatment) to investigate the effects of soil Cu stress on grain yield and its components, dry matter (DM) production and distribution, nutrient uptake and utilization, root system of six rice indica cultivars. The results obtained here is expected to provide some guidelines in cultivation strategies and variety selection for soil Cu-contaminated area. The main results as follows:1. The grain yields of all tested varieties were reduced under soil Cu level of 400 mg·kg-1, with yield reduction being variety-dependent. Among these varieties, IR8 showed relative tolerance to soil Cu contamination, with no significant yield reduction; Yangdao6, IR24 and Sanyou63 have no obvious tolerance to soil Cu contamination, with significant yield loss at P0.05 level, while Liangyoupeijiu and Fengyouxiangzhan are sensitive to soil Cu stress, both of them reaching significant levels (P < 0.01).2. On the panicle number of the six rice cultivars exposed to soil Cu treatment, Yangdao6 and Fengyouxiangzhan decreased significantly at P < 0.01 levels, Sanyou63 and Liangyoupeijiu decreased significantly at P < 0.05 levels, while no significant changes were found for IR8 and IR24 (P > 0.05); Concerning spikelet number per panicle under Cu stress, Yangdao6 increased significantly at P0.01 level, IR8 and Sanyou63 increased significantly at P0.05 levels, while no significant changes (P > 0.05) were detected for Liangyoupeijiu, Fengyouxiangzhan (slight increases) and IR24 (slight decrease), as compared to the control; With regard to filled grain percentage, IR24, Liangyoupeijiu and Fengyouxiangzhan decreased greatly at P0.01 significant levels, IR8 and Shanyou63 decreased at P0.05 significant levels, with slight reduction for Yangdao6. On the 1000-grian weight, Yangdao6 decreased significantly at P0.05 level, while no significant changes were found for Liangyoupeijiu, Sanyou63 (minor decreases), IR8, IR24 and Fengyouxiangzhan (minor increases); As for sink potentials, IR8 increased significantly (P < 0.05), while Yangdao6,Fengyouxiangzhan, Liangyoupeijiu (P < 0.01) and IR24 (P < 0.05) decreased significantly, with minor reduction for Shanyou63 (P > 0.05).3. The final shoot biomass for all test varieties was obviously reduced under soil Cu treatment, with Cu effects on those of Liangyoupeijiu, Fengyouxiangzhan, IR24 and Sanyou63 reaching P0.05 levels; The economic coefficient for all test varieties was obviously reduced under soil Cu treatment, with Cu effects on those of Liangyoupeijiu, Fengyouxiangzhan and Yangdao6 reaching P0.05 levels.4. On the N accumulation in plant of the six rice cultivars exposed to soil Cu treatment, IR24 decreased significantly at P < 0.05 levels, Liangyoupeijiu, Fengyouxiangzhan, Yangdao6 and Sanyou63 decreased obviously, with slight increases for IR8; With regard to N use efficiency for biomass production (NUEp) at maturity, IR24 and IR8 decreased significantly at P < 0.05 levels, Liangyoupeijiu, Fengyouxiangzhan, Yangdao6 and Sanyou63 decreased obviously; On the N use efficiency for grain output (NUEg), Liangyoupeijiu, Fengyouxiangzhan and IR8 decreased significantly at P < 0.05 levels, Yangdao6, IR24 and Sanyou63 decreased obviously.5. Soil Cu treatment significantly (P < 0.05) decreased the number of adventitious roots per pot of Liangyoupeijiu, Sanyou63, obviously decreased that of Fengyouxiangzhan, Yangdao6 and IR24, and slightly increased the number of adventitious roots per pot of IR8 at heading stages; Soil Cu treatment significantly (P < 0.01) shorten the length of single adventitious root of Yangdao6, significantly (P < 0.05) shorten the length of single adventitious root of Fengyouxiangzhan and IR24, obviously shorten the length of single adventitious root of Liangyoupeijiu, Sanyou63 and IR8 at heading stages; Soil Cu treatment significantly (P < 0.01) increased the diameter of single adventitious root of Yangdao6 and Sanyou63, significantly (P < 0.05) increased the diameter of single adventitious root of Liangyoupeijiu, obviously increased the diameter of single adventitious root of Fengyouxiangzhan and IR24, decreased the diameter of single adventitious root of IR8 at heading stages; Soil Cu treatment significantly (P < 0.01) decreased the length of adventitious roots per pot of Liangyoupeijiu, Fengyouxiangzhan and Yangdao6, significantly (P < 0.05) decreased the length of adventitious roots per pot of IR24 and Sanyou63 at heading stages, and decreased the length of adventitious roots per pot of IR8 at heading stages; Soil Cu treatment significantly (P < 0.01 or P < 0.05) decreased the dry weight of roots per pot of Yangdao6, IR24, Fengyouxiangzhan and IR8, decreased the dry weight of roots per pot of Liangyoupeijiu increased the dry weight of roots per pot of Sanyou63 at heading stages; Soil Cu treatment significantly (P < 0.01) decreased theα-NA oxidizing amount of roots per pot of Yangdao6 and IR24, decreased theα-NA oxidizing amount of roots per pot of Fengyouxiangzhan and IR8, increased theα-NA oxidizing amount of roots per pot of Liangyoupeijiu and Sanyou63 at heading stages.6. Soil Cu treatment increased Cu concentration significantly (P < 0.01) in both whole plant and root of all test rice varieties at tillering, heading and maturity stages, respectively, with the magnitude of increases being larger in root than in whole plant.7. In general, the higher Cu concentrations in whole plant and root at the early and middle growth stages of rice, the greater was the toxic effect on rice root growth, and the lowerα-NA oxidizing amount of roots, nitrogen and phosphorus uptake, DM production and thus grain yield were.8. The Cu-induced yield losses (P < 0.01) for Liangyoupeijiu and Fengyouxiangzhan were mainly caused by the decreases in sink potential resulted from less panicles, filled grain percentage, final shoot biomass, economic coefficient, less N use efficiency for grain output (NUEg); The Cu-induced yield losses (P < 0.05) for Yangdao6 was mainly caused by the decreases in sink potential resulted from less panicles, economic coefficient, less N accumulation, less NUEg; The Cu-induced yield losses (P < 0.05) for IR24 was mainly caused by the decreases in sink potential resulted from less spikelet per panicle, less filled grain percentage, lower final shoot biomass, less N accumulation; The Cu-induced yield losses (P < 0.05) for Sanyou63 was mainly caused by less filled grain percentage, lower final shoot biomass, less N accumulation, less NUEg.
|
PDF Full Text Request