Study the effect of humic acid (HA) compound fertilizer on the quality and physiologic index of rape

Fertilizer used in the old vegetable garden for a long time causing a lot of problems like the disequilibrium of soil nutrients, the deterioration of vegetable quality, so several new HA compound fertilizers were applied to rape (Brassica campestris L. ssp. chinensis L. Makino) in sandy and soil culture experiments. The results showed that all fertilizer treatments were notably out-weighted the CK and no significant different yield between the experimental fertilizers. With equal-nutritional quantity, HA compound fertilizer apparently decreased the NO_3-N content and increased Vc, soluble sugar content and SOD, POD, NR activities. Moreover, number 4 (HA-NPK-Zn) was the best among them. It also effectively enhanced the chlorophyll content and made the blade thick, glossy dark green and fresh, which improved the commodity value of rape. With equal soil-water content, the intensity of transpiration increased and the resistance of stoma decreased by HA compound fertilizer ensured the water or other metabolisms vigorously to rape.