Effect Of Salicylic Acid On Physiological Characteristics, Quality And Yield Of Cauliflower Under Water Stress Conditions

The field experiment was conducted to study effects of exogenous salicylic acidon water physiology, leaf protective enzyme activity, photosynthetic pigment content,physiological and biochemical characteristics, quality, yield and water use efficiencyof cauliflower (var. Paris snow) under different watering treatments.The threeirrigation lower limits were artificially controlled as35%,50%and65%of water fieldcapacity of farmland irrigation water, and the irrigation upper limit was controlled as90%. At the same time the treatment of spraying0.1mM salicylic acid (SA) on theleaf was designed. The objective of this study was to provide theoretical basis forwater-saving and drought resisting cultivation of cauliflower in open field in thenorthwest drought area. The main results were as follows:1. In the range from35%to65%of irrigation lower limit, the leaf water potential,leaf relative water content and free water content of cauliflower decreased with soilwater content decreasing. When irrigateon lower limit was35%, spraying SAobviously relieved the effect of water saturation deficit decreasing.2. As irrigation lower limit decreased gradually, leaf electrolyte permeability,MDA and proline contents of cauliflower gradually increased, while glutathionecontent gradually reduced. Spraying SA was helpful for reducing leaf electrolytepermeability and MDA content of cauliflower, improving free proline and glutathionecontents.3. With irrigation lower limit decreasing, the chlorophyll a and chlorophyll b,carotenoid content and chlorophyll a/chlorophyll b of cauliflower leaf decreasedgradually. After spraying0.1mmol/L SA, the photosynthetic pigment contents wereincreased gradually, especially improved obviously when irrigation lower limit was35%.4. With irrigation lower limit decreasing, the SOD, POD, CAT, APX enzymeactivity of cauliflower leaf showed firstly decline then rise. Under50%irrigationlower limit, enzyme activity reached the maximum. When irrigation lower limit was35%, the four kinds of protective enzyme activity of cauliflower leaf increased quickly after spraying SA.5. With irrigation lower limit increased, the nitrate content, soluble sugar, solublesolids content of cauliflower gradually reduced, and Vc content increased firstly thendecreased. When irrigation lower limit was35%, spraying SA had significantlypositive effect on Vc content, while it had negative effect on the nitrate content.6. The yield of cauliflower when50%irrigation lower limit was no significantdifferent from60%irrigation limit. These two treatment were significantly higherthan35%irrigation lower limit. Spraying SA had no significant effect on theprocessing yield.7. Taking all factors into consideration,50%irrigation lower limit of fieldcapacity was evaluated the best option, which had obviously promoting effects on thegrowth and physiological indexes of cauliflower. On the condition of the yield ofcauliflower was guaranteed, its water use efficiency was higher than other treatments.Spraying0.1m mol/L SA can improve cauliflower quality and alleviate droughtstress.