Effect of Drip Irrigation on Strawberry Growth and Yield inside a Plastic Greenhouse

Abstract

Effects of drip irrigation on the growth and yield of strawberries were studied inside a plastic greenhouse. The amounts of irrigation water applied were 0·75, 1·00 and 1·25 times water surface evaporation (Ep) measured by a standard 200 mm diameter pan, and the corresponding regimes were denoted Ep0·75, Ep1·00 and Ep1·25. During the experimental period, soil moisture tension of regimes Ep1·00 and Ep1·25 at 0·2 m depth varied from 5 to 17 kPa, and varied from 5 to 23 kPa at 0·4 m depth; but soil moisture tension of regime Ep0·75 at 0·2 m depth changed from 6·5 to 43 kPa, and soil moisture tension at 0·4 m depth had been over 70 kPa at the end. Plant leaves, flowers and fruits, above-ground biomass, runners, total berry yields, marketable strawberry yields (>5 g), the size of strawberry fruits all increased when the amount of irrigation water increased from Ep0·75, Ep1·00 to Ep1·25. Irrigated water increased strawberry yields not only by increasing the number of berries, but also by increasing the mean weight of the berries. The trends of the irrigation water use efficiency for the plant biomass and the production of total fresh berry yields showed that the lower the amount of irrigation water received, the higher the irrigation water use efficiency. Based on the experimental results, the optimal amount of irrigation water is about 380 mm, the optimal pan factor is about 1·1 and the optimal irrigation water use efficiency for strawberry yield is about 1·63 g mm −1 for strawberry growth and yield inside a plastic greenhouse. So, strawberries grown inside plastic greenhouse should be irrigated using a pan factor of 1·1 as a guideline for irrigation during the full growth seasons. The use of a lower pan factor may reduce the berry yield significantly.