Effects of drip fertigation strategies on root distribution and yield of tomato

Field experiments were conducted in a solar-heated greenhouse to investigate the effects on tomato root distributions and yield of drip fertigation strategies. The treatments included different nitrogen application levels and fertigation strategies that varied the order in which water and nutrient were applied. Two nitrogen application levels of 204 and 372 kgN/hm² and two fertigation strategies of applying nutrient at the beginning and applying water at the beginning of irrigation cycle were used. Tomato roots were sampled at harvest and analyzed by using the software of WinRHIZO. The experimental results show that the total root length, surface area, volume, weight of an individual plant and root density significantly increased with the amount of nitrogen applied. For a given nitrogen level, the strategy of applying nutrient at the beginning resulted in a greater total root length and smaller total root surface area, volume than the strategy of applying water at the beginning. In the profile, the increase of root density was seen in upper layer of soil for the strategy of applying water at the beginning, whereas for the strategy of applying nutrient at the beginning the increase appeared in lower layers of soil. The variation of root with fertigation strategy was more significant for a diameter of less than 1mm. A good correlation between tomato yield and the ratio of the thin root with diameter of less than 1mm to the total root was seen. No significant influences of nitrogen application level and fertigation strategy on tomato yield were observed in the experiments.