Response of Chinese cabbage growth, quality, photosynthesis and nitrogen utilization to new fertilizers in Guizhou yellow soil

The effects of new fertilizers on the yield, quality, photosynthetic characteristics and fertilizer utilization of Chinese cabbage in Guizhou acid yellow soils were investigated in a pot experiment. The soil used in the experiment was typical yellow soil with pH 6.08, collected from the experimental base of Academy of Agricultural Sciences of Guizhou. The four treatments studied in the experiment included the contrast treatment (CK, no nitrogen fertilizer), compound fertilizer (FH, conventional fertilizer), water retaining fertilizer (BS) and stable slow-release fertilizer (WD). The biomass, contents of nitrate, reducing sugar, Vc and free amino acid as well as leaf gas exchange parameters and nitrogen content and utilization of Chinese cabbage were investigated at different times after sowing. The results showed that at 34 days after sowing, BS and WD treatments significantly increased Chinese cabbage biomass. Compared with FH treatment, BS and WD treatments increased Chinese cabbage fresh weights by 4.16% and 41.55%, and dry weights by 22.28% and 62.35%, respectively. Application of new fertilizers also improved nutritional quality of Chinese cabbage. Compared with FH treatment, BS treatment significantly reduced nitrate content by 18.61% while increased contents of reducing sugar, Vc and free amino acid, respectively, by 25.74%, 130.95% and 16.91%. However, WD treatment increased nitrate, reducing sugar and Vc contents, respectively, by 26.68%, 15.35% and 50.00%, while decreased free amino acid content by 14.43%. The application of the new fertilizers also enhanced the photosynthetic capacity of Chinese cabbage leaves, including the net photosynthetic rate (P_n), stomatal conductance (g_s), intercellular CO2 concentration (C_i) and transpiration rate (T^r), forwhich WD treatment had the best performance. The stomata regulation was the main enhancement factor for photosynthetic capacity. Nitrogen uptake of Chinese cabbage obviously increased and nitrogen use efficiency apparently enhanced as well. Average agronomic nitrogen efficiency (AE_N), partial factor productivity (PFP_N), physiological utilization (PE_N) and recovery efficiency (RE_N) for new fertilizer treatments were respectively 48.30 kg.kg^-1, 59.85kg.kg^-1, 95.46 kg.kg^-1 and 52.79%. Then the treatment with the best efficiency was WD treatment, especially for nitrogen recovery efficiency (which was 66.66%). Correlation analysis showed that yield and net photosynthetic rate (P_n), stomatal conductance (g_s) and transpiration rate (T^r) had significant positive correlations. This suggested that improvement in net photosynthetic rate (P_n), stomatal conductance (g_s) and transpiration rate (T^r) increased yield of Chinese cabbage. Concurrently, there was a significant correlation between nitrogen content, physiological utilization (PE_N) and recovery efficiency (RE_N), with r values of 0.937 and 0.978, respectively. This suggested that increase in nitrogen content improved nitrogen utilization efficiency. Furthermore, the new fertilizers significantly enhanced biological yield and photosynthetic characteristics of Chinese cabbage in Guizhou acid yellow soils. The study laid a solid scientific reference and theoretical basis for future applications of new fertilizers in agricultural production in Guizhou Province.