Assessment of Yield Advantages of Bt Rice under Different Pest Control Modes

Researchers from Huazhong Agricultural University in China and partners conducted field experiments to investigate the field performance of insect resistant Bt rice varieties under four pest control modes: (1) chemical control for all the pests; (2) no chemical control for the target pests; (3) chemical control of the target pests; and (4) no chemical control for all the pests.

Results showed that maximum yield advantages of Bt-MH63 (cry1C) and Bt-MH63 (cry2A) over the conventional MH63 were 8.4 and 25.4% under no chemical control for the target pests, respectively. The grain yield of Bt-MH63 (cry1C) was lower than that of conventional MH63 under chemical control for all pests and chemical control for the target pests. Moreover, the grain yield of Bt-MH63 (cry2A) was lower than that of conventional MH63 under chemical control of the target pests only.

Correlation analysis showed that the yield advantages of Bt-MH63 over MH63 were positively correlated with the damage to MH63 (expressed as percentage of white leaves) caused by leaffolders (Cnaphalocrocis medinalis Guenee). Although Bt-MH63 (cry1C) and Bt-MH63 (cry2A) showed great differences in Bt protein contents in their leaves, they had high effective resistances to leaffolders. Based on the results, Bt-MH63 had yield advantages over conventional MH63 when no pesticides were applied against the target pests. However, yield reductions in Bt-MH63 existed when pesticides were applied against the target pests.

Read the abstract at http://www.sciencedirect.com/science/article/pii/S0378429013003171.