Effect Of Soil Water And Fertilization On Fruit Quality And The Leaf Physiological Characteristics Of Tomato

It is vital important to manage soil water and fertilizer scientifically. But because of economic and technique problems, fertilizer and soil water are applied excessively in vegetable field. Therefore, continued research and improving understanding of the soil water and fertilizer management may assist in development of improved vegetable quality and yield.The experiment was conducted in the Institute of Soil and Water Conservation District conducted test sites, Northwest A & F University, Yangling, Shaanxi from 2009 to 2010, to study the effect of soil water content and fertilizer on physiological characteristics of tomato. Three soil water treatments (Wl,55%±5%; Wm,75%±5% and Wh, 95%±5% of field capacity) and three fertilizer levels (Fl, N 0.187g/kg+P₂O₅ 0.131g/kg; Fm, N 0.267g/kg+P₂O₅ 0.187g/kg; Fh, N 0.347g/kg + P₂O₅ 0.243g/kg) were adopted in 2009; Three soil water treatments (soil water with the 2010 design) and two fertilizer levels (Fl, N 0.187g/kg+ P₂O₅ 0.131g/kg+ K2O 0.224 g/kg; Fm, N 0.267 g/kg+ P₂O₅ 0.187 g/kg+ K2O 0.320 g/kg) were adopted in 2010. Fruit quality, leaf protective enzyme system, tomato fruit yield, leaf photosynthetic characteristics and photosynthetic pigment of potted tomato were measured at the fruiting stage. The objective of this experiment was to study the effect of soil water content and fertilizer on tomato physiological characteristics to explore the optimum soil water content and fertilizer amount during the fruiting stage. The major results are as follows:(1) The fruit quality was improved under the WlFm treatment and the penetrant (as free amino acid) keeped high level in fruits under the WmFm treatment in the whole fruiting stages.(2) In the whole fruiting stages, the activities of leaf protective enzymes maintained at a higher level, the MDA content was lower and the membrane lipid peroxidation was weaker under the WmFm treatment, which could postpone the plant senescence and make the plant normal growth. Chlorophyll content of leaves was higher under the WmFh treatment. Nitrate reductase (NR) activity of leaf maintained at higher level under the WmFm treatment and glutamine synthelase(GS) activity was higher under the WmFl treatment.(3) There are significant positive correlations between free amino acid contents and POD activity or Pro content, while there was a significant negative correlation between free amino acid content and MDA content. There were extremely significant positive correlations between soluble protein content or organic acid content and CAT activity or POD activity or MDA content, there were extremely significant negative correlations between Vc content or soluble sugar content and POD activity or MDA content, but there were significant positive correlations between Vc content or soluble sugar content and SOD activity. There were positive correlations between fruit quality and chlorophyll content.(4) ANOVA results showed high significance of the fruit quality, leaf protective enzyme and MDA content in two years between years, soil water and fertilizer treatment, together with interactions among them in pairs.(5) The tomato fruit yield per plant increased with the rising of soil water and fertilizer amount. The water using efficiency was higher under the WmFm treatment.(6) In the whole fruiting stages, the leaf net photosynthetic rate(Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci) and Transpiration rate (Tr) increased under the WmFl and WmFm treatments, while the Ls decreased, the WUE improved under the WlFm treatment. The photochemical efficiency of the PSâ…¡(Fv/Fm), the effective photochemical quantum efficiency (Fv'/Fm'), the actual photochemical reaction quantum efficiency (ΦPSâ…¡), photochemical quenching coefficient (qP) and ETR were higher under the WmFl and WmFm treatments, while the non-photochemical quenching (NPQ) was low. The reduction of the net photosynthetic rate (Pn) was mainly resulted from stomatal limitation, the content of photosynthetic pigment chl.a, chl.b and car improved under the WmFm treatment.(7) There were significant positive correlations between chlorophyll content and the leaf Pn value or Gs value or Ci value or WUE value. There were significant positive correlations between the Pn value and WUE value or Gs value or ETR value or Tr value, but there were significant negative correlations between the Pn value and Fv/Fm value orΦPSâ…¡value or qP value. There were extremely significant positive correlations between Tr value and Fv'/Fm'value orΦPSâ…¡value or qP value or ETR value as well as between the NPQ value and WUE value, while there were extremely significant negative correlations between the NPQ value and Pn value or Fv'/Fm'value orΦPSâ…¡value or ETR value as well as between the Fv/Fm value and Fv'/Fm'value orΦPSâ…¡value or qP value, there were extremely significant positive correlations between Fv'/Fm'value andΦPSâ…¡value or qP value or ETR value.