| The growth and physiological response of the different fertilizer and water treatments was explored.This will provide theoretical foundation for high yield and reasonable water and fertilizer management of the loose-curd cauliflower.In the study,the control group(CK)was the traditional local fertilizer and water management(N: 342 kg·hm-2,P2O5: 212 kg·hm-2,K2O: 284 kg·hm-2;flood irrigation).The experiment group was a 3×3 factorial involving three fertilizer levels as: F1(N: 342 kg·hm-2,P2O5: 212 kg·hm-2,K2O: 284 kg·hm-2),F2(80% F1),and F3(60% F1).The three water application rates were: W1,W2 and W3 which are the 80%,60% and 40% of the maximum field water holding capacity,respectively.The main results are as follows:1.Under water and fertilizer interactions,the plant height,stem diameter,specific leaf weight,and root activity of F1W1 and F2W1 in the experimental group were higher than those of traditional fertilizer treatment.In the experimental group,with the irrigation rate decreasing,the plant height,stem diameter,specific leaf weight and root activity of loose-curd cauliflower under high fertilization level also showed a downward trend,while at low fertilizer level,the plant height,stem diameter,specific leaf weight and root activity did not decline.The yield of traditional fertilizer and water management(CK)was 15.39%,13.56%,and 13.93% lower than that of F1W1,F1W2,and F2W1,respectively.The water and fertilizer interaction had a significant effect on plant height,stem diameter,specific leaf weight,and root activity at each growth stage,but the effect on yield was not significant.2.The chlorophyll content and Hill reaction activity of F1W1,F2W1 and CK were significantly higher than other treatments.In the experimental group,the irrigation condition significantly affected the chlorophyll content and Hill reaction activity.Under the W1 irrigation,the chlorophyll content and Hill reaction activity were increased.The amount of fertilization also had a significant effect on the chlorophyll content and the Hill reaction activity of the loose-curd cauliflower.Increasing amount of fertilization effectively increased the chlorophyll content and the Hill reaction activity in the leaves of loose-curd cauliflower.The water and fertilizer interaction had a significant effect on the chlorophyll content and Hill reaction activity during the cabbage and harvest stages.3.The net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of F1W1 and F2W1 were higher than those of CK.The water and fertilizer interaction had a significant effect on the gas exchange parameters at each growth stage.4.The maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(PSII)and photochemical quenching coefficient(q P)of CK were lower than those of F1W1 and F2W1.In the experiment group,the Fv/Fm,the PSII and q P decreased significantly with reduced water amount and at the level of F1 and F2,which led to the electricity of carbon assimilation.At the level of F3 fertilization,there was no significant difference in Fv/Fm,PSII and q P between the treatments,indicating that the lower level of irrigation under low fertilizer level was not the main factor affecting chlorophyll fluorescence.The water and fertilizer interaction had a significant effect on the chlorophyll fluorescence parameters at each growth stage.5.The antioxidant enzyme activity of F1W1 and F2W1 were higher than those of CK.The MDA content increased from 0.10 ~ 0.15 ?mol·g-1FW in the rosette stage to 0.14~ 0.44 ?mol·g-1FW in the harvest stage.The MDA content of CK was significantly higher than those of F1W1 and F2W1.Under the level of F1 and F2,high irrigation lower limit was beneficial to the antioxidant enzyme activity.Under the F3 fertilization level,the antioxidant enzyme activity under the lower irrigation lower limit was higher.The change of MDA content was opposite to the above antioxidant enzyme activity.With the decrease water amount,MDA content gradually increased,resulting in MDA accumulation.The water and fertilizer interaction had a significant effect on the antioxidant enzyme activities and MDA content at each growth stage.6.The activity of NR,GS,GOGAT,and nitrate nitrogen content and protein content of F1W1,F2W1 and CK were significantly higher than the other treatments.In the experimental group,the activity of NR,GS and GOGAT,the nitrate nitrogen content and protein content were all higher in W1 than in W2 and W3 under F1 and F2,but W3 was higher than W1 and W2 under F3 treatment.The activity of GDH under W1,W2 and W3 irrigation with F2 was higher than those of F1 and F3,indicating that F2 was the most suitable amount of fertilizer in this experiment.The water and fertilizer interaction had a significant effect on nitrogen metabolism enzyme activity and related substances at each growth stage.The comprehensive analysis shows that F2W1(N:274 kg·hm-2,P2O5:170 kg·hm-2,K2O:227 kg·hm-2;the lower limit of irrigation: 80%)is the best combination of fertilizer and water in this experiment.The yield of loose-curd cauliflower under F2W1 treatment was 52181 kg·hm-2,which was 13.9% higher than that of traditional fertilizer treatment,saving 20% of fertilizer and 56.8% of water. |
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