IRRIGATION REGIMES AND GROWTH MEDIA EFFECTS ON GROWTH AND YIELD OF GREENHOUSE CUCUMBER (Cucumis sativus L.)

Abstract

Challenges facing vegetable farmers in Ghana include the inability to determine the particular amount of water required by the crops during different growth stages and adoption of the necessary irrigation practices to maximise profit. Cucumber productivity can be increased by practicing protected cultivation in the form of greenhouse, as it provides a less restrictive environment for growth and development in contrast to open – field cultivation. Although, greenhouse cucumber production increases productivity, the risk of soil borne diseases has negative effect on the crop. This research was carried out in a greenhouse located at Council for Scientific and Industrial Research (CSIR) - Savanna Agricultural Research Institute (SARI), Nyankpala, Northern Region of Ghana from June, 2022 to September, 2022. The study compared the yield obtainable with greenhouse cucumber grown on soil with cocopeat and soil - biochar mixture and the resultant effect on growth and yield under irrigation regimes. The experiment was a 3 x 3 factorial study laid out in Randomized Complete Block Design (RCBD) with three replications. The treatments consisted of irrigation regimes (100 % ETc., 75 % ETc, 50 % ETc) and growth media including (Soil (So), Soil plus Charred rice husk (So + CRH) and Cocopeat (CP)). From the CROPWAT model, the cucumber with highest water requirement for all media was at 100 % ETc giving a value of 237.4 mm/ dec for both So and So + CRH and 237.2 mm/dec for CP; that of lowest water requirement was at 50 % ETc giving a value of 118.8 mm/dec for both So and So + CRH and 118.6 mm/dec for CP. Data was collected on media physico-chemical properties, growth and yield parameters. Determination of the cost benefit of the media also took place. The result of Analysis of Variance (ANOVA) showed CP and So + CRH at 100 % ETc supported optimum growth of greenhouse cucumber. Cucumber growth parameters including: plant height, leaf number per plant, stem girth and flower count were maximised on CP at 100 % ETc. Highest leaf area index was obtained from plants grown on So + CRH at 100 % ETc; chlorophyll content was highest for cucumber plants grown on So at 50 % ETc, while the highest flower abortion occurred on plants grown on So + CRH at 75 % ETc. Plants irrigated at 100 % ETc gave the highest yield of 116.3 t/ha while those irrigated at 50 % ETc gave the lowest yield of 37.8 t/ha. Plant height correlated highly and positively with stem girth and flower count at r = 0.65 and 0.62 respectively; Leaf area index correlated highly and positively with the flower count at r = 0.63 and total fruit count correlated highly and positively with the fruit yield at r = 0.85. Most of the growth parameters were optimal at 100 % ETc and yield obtained from plants irrigated at 75 % ETc was similar to that obtained at 100 % ETc; it is therefore recommended for greenhouse cucumber farmers in northern Ghana to irrigate at 75 % ETc thereby saving water and optimizing yield. Use of So proved to be more profitable compared to CP and So + CRH. This could be due to the high cost of production of CP and high flower abortion associated with So + CRH grown plants, which reduced the yield. More work could be done on combination of CP and CRH for greenhouse cucumber production.