This paper is relevant to the impact areas in the following areas:
| Crops | Rice |
| Traits | Insect Res. (BT), Insect Resistance |
| Countries | China |
| Regions | Asia |
| Tags | nitrogen uptake, nitrogen use efficiency |
Transgenic crops with Bacillus thuringiensis (Bt) have been reported to be effective in controlling pests, and some Bt transgenic lines have been used to develop hybrid crop varieties including three-line and two-line hybrid rice (THR). However, it is unclear whether the insertion of an external Bt gene affects nitrogen uptake and N use efficiency (NUE) along with the grain yield of Bt-THR. Thus, field experiments were conducted in two adjacent fields located at Zhangbang village, Hubei province, China from May to October in 2011 and 2012. Treatments were arranged using a split-plot design with four replications. The main plots were N treatments with three rates (90, 135, 180 kg ha−1) in 2011 and four rates (0, 90, 135, 180 kg ha−1) in 2012. Four different tested varieties were grown in the subplots. The three Bt-THR examined were Guangliangyou-19 (GLY-19), Chuanyou-4198 (CY-4198), and Zheyou-3 (ZY-3), and the non-Bt control was Yangliangyou-6 (YLY-6) which was used as the check for the national variety traits in China at present. Pests (including Bt target pests, diseases and weeds) were strictly controlled to avoid yield loss. No significant differences were observed in the grain yield between GLY-19, ZY-3 and YLY-6 at each N application for both years. However, the grain yield in response to different N rates varied among different Bt-THR varieties and the control. CY-4198 showed a sensitive N response trait, which produced a maximum grain yield at 90 kg N ha−1, and further increases in N rates caused a yield decline. The other Bt-THR varieties demonstrated insensitive N responses similar to the control, where the maximum grain yield was at 135 kg N ha−1 and showed no significant yield decline when applied at 180 kg N ha−1 in both years. Among the three Bt-THR varieties, GYL-19 and ZY-3 demonstrated a similar N uptake ability, agronomic nitrogen use efficiency, N harvest index, N translocation efficiency, and recovery efficiency compared to the control, whereas those for CY-4198 was lower when the N application exceeded 90 kg N ha−1. In conclusion, some Bt-THR varieties (GLY-19 and ZY-3) demonstrated a comparable yield potential to the super hybrid control (YLY-6). Moreover, there was no evidence that insertion of the Bt gene changed N uptake and NUE-related traits, which indicated that the optimal N managements adapted by the THR varieties could also be introduced to Bt-THR. Thus, screening Bt-THR varieties might represent a feasible approach to synergistically improve grain yield and pest resistance without disrupting N nutrition.
Grain yield and nitrogen use efficiency responses to N application in Bt (Cry1Ab/Ac) transgenic two-line hybrid rice (held on an external server, and so may require additional authentication details)
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