Difference Of Yield Of Rice (Oryza Sativa L.) Varieties From Different Eras And Analysis Of Its Causes

Pot experiments with 5 treatments were conducted to investigate the difference of yield in 9 conventional indica rice (Oryza Sativa L.) from different eras, which with near growth duration. Nitrogen fertilizer treatments included no fertilizer (CK), basal fertilizer (BT), Tiller promotion (TP), Spikelet promotion (SP), Spikelet sustaining (SS). The difference of yield and its components, dry matter production, sink-source relationship, nitrogen uptake and utilization, root morphometrics traits and activity were studied to discuss the possible causes of the difference of yield of rice varieties from the different eras and analyse the stabitily of the yield among the different years and nitrogen treatments. Results showed as follows:(1)Whether in CK, or BT, TP, SP, SS, the yield of rice varieties from Eraâ…¡,Eraâ…¢,Eraâ…£were significantly higher than those from Eraâ… .The difference of the yield of rice varieties from Eraâ…¡, Eraâ…¢, Eraâ…£varied with the weather conditions. In good weather conditions, there was no significant difference. In bad weather conditions, the yield of rice varieties from Eraâ…£were significantly higher than those from Eraâ…¡, Eraâ…¢. From the yield and its components, in CK, BT, TP, the yield of rice varieties from Eraâ…¡,Eraâ…¢were higher than those from Eraâ… because of significant increment of spikelet number per panicle. the yield of rice variety from Eraâ…£were higher than those of rice varieties from Eraâ… because of general increment of spikelet number per panicle, 1000-grain weight, seed setting percentage. In SP, SS, the yield of rice varieties from Eraâ…¡was higher than those from Eraâ… because of significant increment of spikelet number per panicle, the yield of rice varieties from Eraâ…¢,Eraâ…£were higher than those from Eraâ… because of general increment of spikelet number per panicle, 1000-grain weight, seed setting percentage. From the biomass and economic co-efficient, the yield of rice varieties from Eraâ…¡were higher than those from Eraâ… because of the significant increment of the biomass and economic co-efficient. The yield of rice varieties from Eraâ…¢and Eraâ…£were higher than those from Eraâ… because of great increment of the biomass. From the source-sink relationship, the yield of rice varieties from Eraâ…¡, Eraâ…¢ and Eraâ…£were higher than those from Eraâ… because of significant increment of sink potential per pot, sink potential per unit leaf area and grain yield per unit leaf area. From the nitrogen uptake and utilization, the yield of rice varieties from Eraâ…¡, Eraâ…¢and Eraâ…£were higher than those from Eraâ… because of significant increment of nitrogen uptake at maturity and nitrogen use efficiency for grain yield. From the root morphometrics traits, the increment of the yield of rice varieties from Eraâ…¡was related to the significant increment of the dry weight of roots per plant. The increment of the yield of rice variety from Eraâ…¢and Eraâ…£was related to significant increment of the number of adventitious roots per pot, total length of adventitious roots per pot, the dry weight of roots per pot. From the root activity,the increment of the yield of rice varieties from Eraâ…¡,Eraâ…¢and Eraâ…£was related to the significant increment of root total absorption area per pot ,root active absorption area per pot and root activity per pot.(2) In the BT treatment, the yield-increasing effect of rice varieties from the different era all was best, then in TP and SP, in the SS treatment the effect was worst. In the TP treatment, the stability of yield of rice varieties from different eras among the different years was the best, next in CK and BT, again in SP, in SS the stability was the worst. In the SS treatment, the instability of yield of rice varieties from the different eras among the different years was because of great difference of the number of panicles and seed setting percentage, biomass and economic co-efficien, sink potential per pot, sink potential per unit leaf area and grain yield per unit leaf area, the nitrogen uptake at maturity and nitrogen use efficiency for grain yield, total length of adventitious roots per pot, root total absorption area per pot, root active absorption area per pot and root activity per pot, root activity per unit dry weight of adventitious roots among the different years.(3)The stability of yield of rice variety from Eraâ…£among the different years was the best, next Eraâ… and Eraâ…¡, the stability of yield of rice variety from Eraâ…¢was the worst. The instability of yield of rice varieties from Eraâ…¢was because of great difference of the seed setting percentage, the biomass, grain yield per unit leaf area, the nitrogen uptake at maturity and nitrogen use efficiency for grain yield, total length of adventitious roots per pot, the dry weight of roots per pot, root total absorption area per pot, root active absorption area per pot among the different years.