The Study On Substrate Formula And Fertilizer Use Efficiency Of Vegetable Plug Seedlings Under Ebb And Flood Irrigation

The production of solanaceous and gourd vegetables occupies an important position in the vegetable production in China. Vegetable plug seedling production is the main way to produce vegetable seedlings. However, traditional irrigation methods related to seedlings productions has drawbacks such as the waste water and soluble fertilizer. Ebb and flood irrigation was a new way to produce plug seedling which developed in rencent years.This thesis was to select an optimal substrate formula of solanaceous and gourd seedling for ebb and flood irrigation. The effects of ebb and flood irrigation on the use efficiency of nitrogen (N), phosphorus (P) and potassium (K) and the growth and development of these seedlings were studied.In experiment 1, There were five substrate formulas for tomato, pepper and eggplant seedlings,such as A) peat moss, vermiculite and perlite (3:1:1, v/v); B) peat moss and perlite (3:1,v/v); C) peat moss and perlite (2:1, v/v); D) peat moss, perlite and quartz sand (3:1:0.5, v/v); E) peat moss and perlite (3:1, v/v) and 5% γ-polyglutamic acid (w/w) (5% γ-PGA). In experiment 2, tomato and pepper seedlings were grown in 105 cell or 98 cell plug trays, with substrates containing peat moss, vermiculite and perlite (3:1:1, v/v) under overhead or ebb and flood irrigation, while eggplant seedlings were grown in 105 cell or 98 cell plug trays, with substrates containing peat moss, vermiculite and perlite (3:1:1, v/v) under overhead irrigation or with substrates peat moss and perlite (3:1, v/v) under ebb and flood irrigation. In experiment 3, there were five substrate formulas for cucumber, melon and watermelon seedlings such as A) peat moss, vermiculite and perlite (3:1:1, v/v); B) peat moss, vermiculite and perlite (3:1:2, v/v); C) peat moss and perlite (2:1, v/v); D) peat moss and perlite (3:1, v/v); E) peat moss and perlite (4:1, v/v). Furthermore, in experiment 4, cucumber, melon seedlings and watermelon were grown in105 cell or 72 cell plug trays, with substrates containing peat moss, vermiculite and perlite (3:1:1, v/v) under overhead or ebb and flood. For experiments 1 and 3, the "physical and chemical properties" of substrates and the growth parameters of seedlings were measured. For experiments 2 and 4, total N, P and K absorption of seedlings and the substrates were determined. The growth parameters like shoot length, stem diameter, shoot dry weight, roots dry weight, root shoot ratio, seedlings index and chlorophyll were recorded.The main results are found as follows:Firstly, without an addition of 5% γ-PGA, there was no significant difference in the seedling indexes of tomato, pepper and eggplant seedlings among treatments (P< 0.05). Although, peat moss, vermiculite and perlite (3:1:1,v/v) was the optimal substrate formula for tomato and pepper seedlings. It achieved the higher shoot dry weights with averages of 231.0,102.0 mg/seedling, the higher root dry weights with averages of 25.0,23.0 mg/seedling and the higher seedling index with averages of 33.59,25.71, respectively. Beside, peat moss and perlite (3:1, v/v) was the optimal formula for eggplant seedlings. It gained the higher seedling index (63.60), the higher shoot dry weight (281.17 mg/seedling) and the higher root dry weight (23.17 mg/seedling). Secondly, the total N absorption, N use efficiency of the tomato, pepper and eggplant seedlings under ebb and flood irrigation were higher than the overhead irrigation with the 105 cell or 98 cell plug tray. In contrast, total P absorption, P use efficiency of the tomato seedling grown in the 105 cell plug tray under the ebb and flood irrigation was higher than overhead irrigation. In case of total P absorption and P use efficiency of pepper, eggplant seedlings under the ebb and flood irrigation were higher than the overhead irrigation either 105 cell or 98 cell plug tray. The total K absorption, K use efficiency of the tomato and eggplants seedlings under ebb and flood irrigation were higher than overhead irrigation either with the 105 cell or 98 cell plug tray. Total K absorption, K use efficiency of the pepper seedlings grown in 98 cell plug tray under ebb and flood irrigation were higher than that under overhead irrigation. Thirdly, There was no significant difference in the seedling index of cucumber, melon and the watermelon seedlings among treatments (P≤0.05), but the substrate formula of peat moss and perlite (4:1,v/v) provided the higher environment for cucumber, melon and watermelon seedlings to achieve the higher shoot height with averages of 27.16,17.77 and 17.36 cm, the higher stem diameter with averages of 3.65,3.19 and 3.30 mm, the higher shoot dry weight with averages of 328.30,270.20 and 253.30 mg/seedling, the higher root dry weights with averages of 40.30, 34.30 and 16.40 mg/seedling, respectively. Finally, total N, P, K absorption and N, P, K use efficiency of cucumber and watermelon seedlings and total N, P absorption and N, P use efficiency of melon seedlings under ebb and flood irrigation were higher than that grown under overhead irrigation either with the 105 cell or the 72 cell plug tray. Acceptably, total K absorption and K use efficiency of melon seedlings under ebb and flood irrigation were higher than that grown under overhead irrigation with the 72 cell plug tray.In conclusion, γ-PGA enhanced the growth and development of tomato, pepper seedlings. Without application of γ-PGA peat moss, vermiculite and perlite (3:1:1, v/v) was the optimal formula. For eggplant seedling, the peat moss and perlite (3:1, v/v) was the optimal formula. The peat moss and perlite (4:1, v/v) was the optimal formula for cucumber, melon and watermelon seedling. Compared with the overhead irrigation, the ebb and flood irrigation was the better way to produce vegetable plug seedlings. It had not only brought an optimal growth and development of seedlings, but also enhanced N, P and K use efficiency in our studies.