期刊
JOURNAL OF PLANT NUTRITION
卷 30, 期 4-6, 页码 659-670出版社
TAYLOR & FRANCIS INC
DOI: 10.1080/01904160701289206
关键词
Bt-transgenic cotton; K+ deficiency; conventional cotton; Michaelis-Menten kinetics
Bacillus thuringensis (Bt) transgenic (insect-resistant) cotton cultivars senesce prematurely under potassium (K+) deficiency, more often than conventional cultivars, in the North China Plain. To verify if Bt-transgenic cotton was more susceptible to K+ deficit, two transgenic cultivars,'CCRI41' and 'DP99B', and two conventional cultivars,'CCRI 35' and 'CCRI36', selected from widely used cultivars in China, were used in a seedling hydroponic study. The culture solution K+ concentration was 0.5 mM for high K+ and 0.02 mM for low K+ conditions. Seedlings of all four cultivars accumulated more dry matter and K+ when grown at high K+ than low K+ conditions. However, under low K+ condition, the dry weight and K+ content of Bt-transgenic cultivars CCRI 41 and DP 99B were lower than those of the conventional cultivars CCRI 36 and CCRI 35. The results indicated that Bt-transgenic cultivars CCRI 41 and DP 99B were more sensitive to K+ deficiency than conventional cultivars CCRI 36 and CCRI 35, which could be the reason for premature senescence symptoms observed from fields of Bt-transgenic cotton under K+ deficiency. Seedlings of all four cultivars had a higher K+ use efficiency (KUE) under low K+ than high K+ conditions, but the KUE did not account for the differential responses between Bt-transgenic and conventional cultivars at the low K+ concentration. The K+ depletion results did not reveal the mechanism for the above differential responses in V-max and K-m of the seedlings either. Further experiments with more cultivars are needed to clarify the differential mechanisms in these genotypes.
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