Knowledge of the required amount of irrigation and the time in the day to irrigate is very important for the efficient use of irrigation water and the maximization of vegetable yield and quality. In this experiment, the effect of time of irrigation (morning and evening) and amount of irrigation (100%ETc, 90%ETc and 80%ETc) on the growth, yield, physicochemical quality, shelf life, WUE and economic value of sweet pepper was investigated using completely randomized design with 3 replications. Plant growth increased as irrigation amount decreased from 100%ETc to 80%ETc for both crops irrigated in the morning and evening but was high in irrigating in the evening than in the morning. Fruit yield was significant and reduced as amount of irrigation decreases (100% > 90%ETc > 80%ETc) in both morning and evening irrigated crops. The yield was high in crops irrigated in the evening than the morning counterparts. Physicochemical qualities were better in less irrigated crops (80%ETc and 90%ETc) than full irrigated crops (100%ETc) for both morning and evening irrigated crops. Fruits from crops irrigated in the morning had better physicochemical qualities (Firmness, TSS, TA and pH) than fruits of crops irrigated in the evening. Shelf life was significant and increases as irrigation amount reduces for both morning and evening irrigated crops. Irrigating in the evening with 90%ETc had the highest WUE of 6.5Kg/m3 and a cost-benefit ratio of 1:30.81. Irrigating sweet pepper in the evening with 10% reduction in CWR (90%ETc) have no significant effect on fruit yield and it improves fruit quality, extends shelf life as well as increase WUE and maximize profit.

Background to the Study
Sweet pepper (Capsicum annuum) belongs to the family Solanaceae and it is known to originate from Central and South America. Sweet pepper is an important vegetable crop in many countries of the Tropical and Subtropical regions; especially in Africa where it is an important component of diets (Adetula and Olakojo, 2006). According to Wolff (1999), vegetables account for 96% of the world’s total food and 4.9% of total expenditure in Ghana. However, FAOSTAT (2013) revealed that sweet pepper production in Ghana is low and export is only 117 tonnes annually out of a total world production of over 31 million tonnes. Sweet pepper fruit is a large, sweet, crisp, bell-shaped fruit of the pepper family. It is consumed raw as in salads as well as in cooked form as in stew. Sweet pepper is an excellent source of vitamins A and C, two very important antioxidants (Raemaekers, 2001) and also contains a small quantity of Vitamin K which is important in bone health. It is available in different bright colours including red, yellow, green and orange, with green being the commonly grown one in Ghana.

Sweet pepper has been classified as very susceptible to water stress, with blossom stage being the most sensitive period (Bruce et al., 1980) and this affects the yield and quality of the fruit produced. According to Antony and Singandhupe (2004), the total pepper yield was less at lower levels of irrigation. Della Costa and Gianquinto (2002) also reported that continuous water stress significantly reduced total fresh weight of pepper fruits. A similar result was reported by Gencoglan, Akinci, Ucan, Akinci, and Gencoglan (2006), that, reducing the crop evapotranspiration (ETc) or deficit irrigation significantly affected the fruit numbers, fruit dry weight and dry yield of hot pepper whilst the average fruit numbers increased over 3 times with fully irrigated crops (100%ETc). For high quality yields, an adequate water supply at the right time in the day is required throughout the growing period. Reduction in water supply during the growing period in general has an adverse effect on yield and quality of the fruits. Doorenbos and Kassam (1979) reported that the period at the beginning of the flowering stage is most sensitive to water shortage and soil water deficit in the root zone during this period should not exceed 25%. According to them, water shortage just prior and during early flowering reduces the number of fruits and is greater under conditions of high temperature and low humidity. The concluded that controlled irrigation is essential for high yields because the crop is sensitive to both over and under irrigation.

In Ghana, supply of water for irrigation is limited, and thus cannot meet the continuously increasing demand of water for irrigation in most cases (Kirda et al., 2004; Wakrim, Wahbi, Tahi, Aganchich, & Serraj, 2005). Due to this, irrigation water supply for vegetable crop production especially during the off season is a major constraint for commercial production. The efficient use of irrigation water is therefore becoming increasingly important, and alternative efficient water application methods such as deficit irrigation, partial root zone drying may contribute substantially to making the best use of water for agriculture and improving irrigation efficiency Nagaz, Masmoudi, & Mechlia, 2012). Competition for water resources among Ghana’s industrial, domestic and agricultural sector has increased in recent times. This has led to the reduction in the amount of water supplied for agricultural purposes (Kirda, 2002). According to Kere, Nyanjage, Liu and Nyalala (2003), the growth, yield and quality of sweet pepper and most vegetables, are highly dependent on the amount of water supplied. There is therefore the need to adopt irrigation management strategies, which may allow saving irrigation water and still maintaining satisfactory yield of production (Costa, Ortuño, & Chaves, 2007) in such countries which is welcomed.

Reducing the amount of CWR or ETc (deficit irrigation) has been identified as one of the strategies to improving water use efficiency, WUE. Deficit irrigation is a water saving strategy under which crops are deliberately allowed to sustain some degree of water deficit and yield reduction (Pereira, Oweis, & Zairi, 2002). Zegbe-Doninguez, Behboudian, Lang; Clothier (2003), defines it as irrigating the root zone with less than the required water for evapotranspiration of the crop. Reducing the CWR is an efficient way of saving irrigation water without losing significantly from crop yield and quality. This irrigation strategy according to Dorji, Behboudian and Zegbe-Dominguez (2005), could be feasible for pepper production where the benefit from saving water outweighs the decrease in the total fresh fruit yield. Irrigation amount and time of irrigation affect the yield and quality of fruits and vegetables. Vegetable quality mainly firmness, total soluble solids and acid contents are affected by water stress (Vijitha and Mahendran, 2010). The aim of reducing the required irrigation of a crop is to increase the WUE, to generate water stress at a level without excessive yield loss in the production period of the plant and to obtain the highest yield corresponding to each unit of water at a desirable quality (Kirda, 2002).

Water is limited and therefore important to know, how to timely irrigate with the least amount of water that will optimize yields, water use efficiency and ultimately profits (Payero, Tarkalson, Irmak, Davison, & Petersen, 2009). Due to this water management practices that will help conserve water for the sustainability of agriculture production are very important (Nurudin, 2001). Irrigation water management strategy such as irrigating crops at the right time with the exactly needed irrigation amount seeks to maximize yield. However, under local practices, irrigation is typically applied on a routine basis either in the morning or the evening, depending on the time that suits the farmer, without considering the water requirement (ET) of the crop and the right time to supply to meet that requirement, therefore usually supply water to exceed the crop water requirements (Nagaz et al., 2012). This may result in high water losses and low irrigation efficiency. Therefore, the study was undertaken to assess the effect of time and amount of irrigation on the growth, yield and quality and shelf life of sweet pepper to determine the best time of irrigating and what amount of irrigation will maximize crop yield and WUE, improve on fruit quality and profit of sweet pepper production in Ghana.

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Item Type: Ghanaian Topic  |  Size: 116 pages  |  Chapters: 1-5
Format: MS Word  |  Delivery: Within 30Mins.


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