Tuber number per plant and average tuber weight per plant decreased with the increase in water deficit under all N levels and the trend was similar to the yield trend. Tuber number was more resistant to water deficit than tuber weight, where the decrease in tuber yield in the water deficit treatments was mainly due to a decrease in tuber weight. The correlation analysis between tuber yield and tuber number was relatively weak (R2 = 0.518), indicating that tuber number was not the main reason for yield reduction ( Fig. 1a). On the other hand the correlation analysis between tuber yield and average tuber weight showed a very strong correlation (R2 = 0.982), which indicates that the increase in tuber yield in different treatments was attributed mainly to the increase in tuber weight ( Fig. 1b). Previous studies have also reported significant tuber yield and size reductions with the reduction of applied water ( Yuan et al., 2003 and Onder et al., 2005), but genotypes showed significant differences in response to water stress ( Steyn et al., 1998). Tuber weight increased with increase in N level up to the highest level of application and the trend was similar to the yield trend. However, tuber number was not significantly affected by the increase in N levels. The interaction effect between irrigation and nitrogen for total yield, tuber number and tuber weight was significant, indicating that both factors did not act separately. Tuber yield increased up to the highest level of N (N340) at W1.0 and W0.8, but the response to added N was observed only up to N280 and N220 at W0.6 and W0.4 treatments, respectively.
Full-size image (28 K)
Tuber number per plant and average tuber weight per plant decreased with the increase in water deficit under all N levels and the trend was similar to the yield trend. Tuber number was more resistant to water deficit than tuber weight, where the decrease in tuber yield in the water deficit treatments was mainly due to a decrease in tuber weight. The correlation analysis between tuber yield and tuber number was relatively weak (R2 = 0.518), indicating that tuber number was not the main reason for yield reduction ( Fig. 1a). On the other hand the correlation analysis between tuber yield and average tuber weight showed a very strong correlation (R2 = 0.982), which indicates that the increase in tuber yield in different treatments was attributed mainly to the increase in tuber weight ( Fig. 1b). Previous studies have also reported significant tuber yield and size reductions with the reduction of applied water ( Yuan et al., 2003 and Onder et al., 2005), but genotypes showed significant differences in response to water stress ( Steyn et al., 1998). Tuber weight increased with increase in N level up to the highest level of application and the trend was similar to the yield trend. However, tuber number was not significantly affected by the increase in N levels. The interaction effect between irrigation and nitrogen for total yield, tuber number and tuber weight was significant, indicating that both factors did not act separately. Tuber yield increased up to the highest level of N (N340) at W1.0 and W0.8, but the response to added N was observed only up to N280 and N220 at W0.6 and W0.4 treatments, respectively.
Full-size image (28 K)
การแปล กรุณารอสักครู่..