Effects of Water Application Levels on Growth Characteristics and Soil Water Balance of Tomatoes in Greenhouse
Obiero J. P. O
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Abstract - The effect of water application levels on growth characteristics and soil water balance of tomato grown in greenhouse were investigated. The study was conducted in two greenhouses located at Matinyani Secondary School and Kyondoni Location in Kitui County, Kenya. The variation of growth characteristics (plant height, stem diameter, fruit diameter and fruit weight) and extraction of soil water with time were monitored. Four irrigation water application levels namely T1-1.2, T2-1.0, T3-0.8 and T4-0.6 served as treatments. These were 120, 100, 80 and 60 % of crop water requirements computed using Piestley-Taylor model. The irrigation frequencies were daily and 1-day respectively at Matinyani and Kyondoni greenhouses. For the daily and 1day irrigation frequencies respectively, applied irrigation water varied from 548 to 274 mm and from 255 to 128 mm while actual evapotranspiration varied from 537 to 246 mm and from 227 to 108 mm in T1 to T4 treatments. This study revealed that different water application levels had significant effect on growth characteristics, soil water balance and yield of tomato crop. Low water application levels as well as less irrigation frequencies reduced crop growth and yield and also led to low soil water content. Daily irrigated treatments produced the best growth characteristics, the best fruit quality and the highest yield. In particular, T1 treatment produced the best stem diameter, plant height, fruit weight, fruit diameter and yield as 16.74 mm, 2.31 m, 129 g, 62 mm and 4.44 kg m-2 respectively. In terms of water use and irrigation water use efficiencies, T4 treatment produced the highest as 11.90 and 13.26 kg m-3 respectively. Under scarce water resources, T3 treatment (80 % ETc) under daily irrigation frequency was considered the most suitable water application level for tomato crop grown inside a greenhouse and therefore recommended. Keywords – Evapotranspiration, Greenhouse Farming, Irrigation Frequency, Protected Cultivation, Water Resources.