Potassium deficiency in rice induced early heading

In a long-term field experiment with rice-wheat rotations conducted in Guanghan city, Sichuan province of China, it is of interest to observe that the K omission plot has headed about one week earlier (Fig. 3 right plot with more headed rice) than the other treatments since 2008, three years after initiation of the experiment. The rice grain yield was reduced by 8-16% compared to the optimal treatment (OPT). In the dry winter season, however, wheat yield was reduced by 9-37% by omitting K but no early heading has been observed since three years after beginning of the experiment. The results indicate that K deficiency becomes more severe under dry and cold winter season than in the warm and moisture summer season, and different crops respond to K deficiency differently. Thus, under the rice-wheat rotation heavier dose of K fertilizer to winter wheat should be considered.

Fig. 1 The plot with omission of K (right plot - OPT-K) induced early heading of rice