Effects Of Nutrient Concentration Changes On Yield, Quality And Nutrient Absorption Of Tomato

The regulation of nutrient solution concentration is an important part in soilless culture. Tomato growth period is longer and its demands of nutrient in different growing phases are very different. The aim of this study to investigate the effects of nutrient concentration changes in vegetative growth stage and reproductive stage on the yield, quality and nutrient use efficiency of tomato. The experiment was conducted with the material of tomato in the greenhouse of key laboratory of agricultural soil and water engineering in arid and semiarid area of ministry of education of Northwest A&F University in Yangling District, Shanxi Province in April 2014. In order to provide theoretical basis for soilless cultivation technology of high yield and good quality, the study on effects of nutrient concentration changes in vegetative growth stage and reproductive stage was conducted. The main results are as follows:1. Changes of nutrient concentration in vegetative growth stage and reproductive stage both had important effects on growth indicators of tomato. No matter in vegetative growth stage or reproductive stage, increasing nutrient solution concentration appropriately would promote plant height, stem diameter, leaf length and leaf width. It was advantageous to the vegetative growth of plants. The growth indexes of tomato, including plant height, stem diameter, leaf length and leaf width, all presented a trend of "S" type curve in the whole growth period. Logistic curve model was matched to the accumulation of plant morphological growth trend along with growth period. The results showed that the fitting were very well and the precision was higher.2. Changes of nutrient concentration had different effects on the yield of tomato. Yield of tomato was increased first then decreased with the nutrient concentration enhanced in vegetative and reproductive growth stages. Nutrient solution was no help to the increase of production if the concentration was too high or too low. This illustrated that improving nutrient solution concentration properly could contribute to the yield of tomato.3. Changes of nutrient concentration had different effects on the quality of tomato. Lycopene, soluble solids, soluble sugar contents rose first then declined with the nutrient concentration enhanced in vegetative and reproductive growth stages. While vitamin C, organic acid and nitrate content showed a trend of increasing gradually. Therefore suitable changes of nutrient concentration in vegetative and reproductive growth periods could promote the quality of tomato effectively. However there was no good for the quality indexes if the concentration was too high or too low. On the whole, the quality of the second cluster tomato was better than the first cluster tomato. Lycopene, vitamin C, soluble solids, soluble sugar contents of the first cluster tomato were higher than the second one, but organic acid was lower. And there was no significant difference of nitrate content between the two clusters tomato.4. Total dry matter accumulation of tomato plants showed an increasing trend with the development of the nutrient solution concentration in vegetative and reproductive growth stages. The proportion of the aboveground part became larger gradually, and most of the additional accumulation was distributed to leaves and fruits of tomato so that we could obtain a more reasonable distribution of dry matter in the plant tissues and organs. Improving the nutrient solution concentration was beneficial to increase the absorption of nutrients. The uptake of nitrogen, phosphorus, potassium, calcium, magnesium would present an increasing trend with the nutrient concentration enhanced in vegetative and reproductive growth stages. The ranking of the demand for nutrients in the tomato whole life were Ca > N > K > P > Mg.5. The proportion of nutrients absorbed by tomato plant was different. It seemed that the absorption ratio of calcium was higher than that nitrogen and potassium, and far higher than that of phosphorus and magnesium. So that we could conclude that calcium was the most important element for tomato. The absorption ratio of nitrogen, phosphorus, potassium, calcium, magnesium was 1:0.25~0.30:0.91~1.01:0.99~1.23:0.27~0.36 in the whole growth period. The nutrient use efficiency decreased gradually with the nutrient concentration developed in vegetative and reproductive growth stages. And the nutrient solution concentration in reproductive stage had a highly significant effect on the uptake and use efficiency of nitrogen, phosphorus, potassium, calcium, magnesium.6. The optimal change of nutrient concentration was that pouring the 4/3 folds nutrient concentration in the vegetative growth stage and 1or 4/3 folds nutrient concentration in the reproductive stage considering both yield and quality of tomato.