Abstract: In order to guide the fertilization management for vegetable farmers and relieve the increasingly severe competition pressure of vegetable planting, experiment was conducted which included different nitrogen fertilizer amount, and then, the digital image of the population canopy was obtained on the 20th (D20), 30th (D30), 40th (D40) and 50th (D50) days after sowing of Chinese cabbage through smart phone. Meanwhile, the fresh yields of the cabbage were measured. The results showed that the fresh yield changes of different treatments during different times were all showed that the N17.5 and N20 were significantly higher than that of no nitrogen fertilizer (N0) treatment. The fresh yield of N17.5 was increased by 27.82%~52.85% than N0. The relationship between canopy red light (R), green light (G), and fresh yield of vegetable could be fitted with a quadratic curve. The equations were y = -0.092 6x2 + 23.365x - 242.53 (R2= 0.581 8), y = -0.044x2 + 15.843x + 50.495 (R2=0.724 9). However, there was no significant relationship between blue light (B) value and fresh yield. Furthermore, the verification experiment indicated that the canopy R and G values could better predict the Chinese cabbage fresh yield. |