Effects of temperature gradient generated by fan-pad cooling system on yield of cabbage grown using fertigation technique under side netted rain shelter

M. Yaseer Suhaimi, S. Mahamud, A.M. Mohamad, K. Rezuwan, H. Fadhilah Annaim Huda and J. Azman

Abstract

A field experiment was carried out to determine the effect of temperature gradient generated by fan-pad cooling system on yield of KY Cross cabbage grown using fertigation technique under 30 m long x 10 m wide x 4.5 m high rain shelter with side netting. The fan-pad cooling system provides evaporative cooling inside the shelter and lowers the air temperature significantly below ambient. The temperature in the structure was 3–5 °C lower than the outside temperature. With 70% efficiency, the system was able to reduce from 42 °C of the outside air to 33.6 °C when exiting the cooling pad. However, the temperature in the shelter increased as the air moved from cooling pad towards the exhaust fans producing a temperature gradient across the length of the shelter (up to 4.5 °C). The temperature gradient caused a negative correlation between the cooling pad distance and the canopy diameter as well as yield of cabbage. The average canopy diameter (77.34 cm) and cabbage head weight (2.62 kg) after 75 days were significantly higher towards the cooling pad. The further the distance between the plants and the cooling pad, the smaller the canopy diameter (48.85 cm) and cabbage head weight (0.65 kg). Grade 1 cabbage heads were produced from the first 12.35 m from the cooling pad (average weight 2.5 kg). At 15.35–21.35 m, the cabbage heads fall into grade 2 with an average weight of 1.33 kg, while grade 3 cabbage heads were produced between 24.35–27.35 m from the cooling pad.

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