Effect of rhizosphere cooling on tomato crop performance under controlled environment structure

C.H. Mohammud, M.K. Illias, O. Zaulia, S.S. Ahmad Syafik and M.Y. Angelina Ho

Abstract

In-house temperature build-ups under controlled environment structures can result in media moisture stress, photosynthetic reduction and serious plant wilting in crops, which are all factors that affect crop development. Research had been undertaken to explore cooling the rhizosphere of the plants instead of cooling this structure. A water chilling system delivers predetermined chilled water at 25, 20 or 15 °C through piping was developed to chill the root zone of tomato. This system can be adapted into existing controlled environment structures and fertigation systems with minor amendments. Research studies conducted showed that controlled chilling of the rhizosphere of tomato significantly increased the vegetative growth and yield of tomato. Chilling enhanced the vegetative growth with 7.4% longer plant length, 8.8% bigger stem diameter and 3.6% longer internodes and 1 – 13% more root volume. Tomato raised in chilled root zone was also found to have 11.8% more fruit number, 21.6% more fruit weight per plant, 3.3% heavier fruit weight and 22.7% higher yield than conventional method. During postharvest storage at 25 °C, root zone cooling showed significant (p <0.05) effect on lightness, chroma, firmness and total soluble solids but did not affect hue and weight loss. However, at 8 °C storage, root zone cooling showed significant (p <0.05) effect on chroma and ascorbic acid but not on lightness, hue, firmness, weight loss and TSS.

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