ABSTRACT
The rapid population increase and land scarcity calls for an alternative means of production system for sustenance of the human race. This prompted an investigation into the growth, yield and consumer acceptance of sweet pepper (Capsicum anuum L) as influenced by open field and greenhouse production systems at the University of Ghana Forest and Horticultural Crops Research Centre, Okumaning – Kade in the Eastern Region of Ghana. The experiment was conducted in the minor season (dry season) from October 2014 to March 2015.
A 2×9 factorial was laid out in Randomized Complete Block Design with three replications. The experiment consisted of two production systems (greenhouse and open field) and nine varieties of sweet pepper (California Wonder- CW, Yolo Wonder -YW, Kulkukan- KK, F1 Nobile- FN, Crusader- CS, Guardian-GD, Embella 733- EM and Caribbean Red- CR, Pepper 1-P1). Growth indices (plant height, girth, leaf number, biomass dry weight and chlorophyll content) and yield components (fruit length, width, seed number, fruit number per plant fruit weight) of sweet pepper plant were ascertained. It was done to elucidate the difference of growth and development among the varieties as well as their consumer acceptance with regard to greenhouse and open field production systems.
The results obtained indicated that, the greenhouse system significantly affected the growth and yield parameters. Crusader-CS, Kulkukan- KK and California Wonder- CW, significantly had a higher, growth, development and fruit yield enhanced in the greenhouse; California- CW and Crusader- CS also responded significantly in the open
field with Yolo Wonder attaining higher net returns. Results also demonstrated that the greenhouse varieties were highly preferred and accepted by consumers than the open field and this may be attributed to its higher quality.
CHAPTER ONE INTRODUCTION
1.1 Background of the study
Sweet pepper (Capsicum annum L.) belongs to the family Solanaceae, which is an important group of vegetables grown extensively and also widely cultivated in almost every country of the world (Channabasavanna and Setty, 2000). It thrives best in warm climate, where frost is not a problem during the growing seasons. In general, it requires temperatures ranging from 25-35 °C (Olalla and Valero, 1994). The sweet pepper of commerce also known as Bell pepper (Sinnadurai 1992), is one of the most varied and widely used foods in the world; it originated in Mexico and Central America regions and Christopher Columbus encountered it in 1493 (Kelley and Boyhan 2009). Sweet pepper is the world’s second most important vegetable after tomato (Anon, 1989). It is one of the most important vegetable grown in other parts of sub-humid and semi-arid tropics (Aliyu, 2000)
FAO (1992) reported that, 10 million metric tons of fresh peppers were produced on 1.1million hectares of land which ranked pepper in the middle range of vegetables in terms of popularity. In 2007, over 26 million metric tons of pepper was produced globally (U.S. Dept. of Agriculture, 2008a). China ranked first, producing more than 50% of the world’s pepper, while the United States (U.S.) ranked sixth with about 855,000 metric tons produce (U.S. Dept. of Agriculture, 2008a).
The fruits of sweet pepper are harvested either at green mature stage or at colouring stage and are a very good source of vitamin A and C and other nutrients having great demand in big cities and other urban areas of the country. One medium green bell pepper can provide up to 8 percent of the recommended daily allowance of Vitamin A, 180 percent of Vitamin C, 2 percent of calcium and 2 percent of iron (Kelley and Boyhan, 2009). Sweet pepper contributes substantially to our diet, it is a good source of vitamins A, C (More than that obtained from tomato), E, B1, B2, and D (Muhamman and Auwalu, 2009). A phenolic compound called capsaicin is responsible for the pungency in peppers. Pepper is grown as an annual crop due to its sensitivity to frost and is actually herbaceous perennial and will survive and yield for several years in tropical climates (Peet, 1995; Kelley and Boyhan, 2009).
According to Norman (1992), the growing of sweet pepper in West Africa is confined to urban centers but recently large scale or commercial productions has been undertaken under irrigation in the rural areas. It is very vulnerable to frost and grows poorly at temperatures between 5 and 15 °C (Bosland & Votava, 1999). The optimum temperature range for sweet pepper growth is 20 to 25 °C. There are several factors that influence the growth and yield of pepper, some of which include temperature, relative humidity, day length, photoperiod etc. Along with other factors which affect the per unit area production like nutrition, cultivar, growing system and soil fertility, plant density has its significance (Agarwal et al., 2007). Plant densities and arrangements in the open field strongly decide the utilization of intercepted solar radiation mainly due to leaf area index.
It is therefore imperative to note that green pepper in Ghana is suited for most of the ecological zones with good climatic and edaphic parameters to support it growth in the
open-field cultivations whereas greenhouse technologies enable the cultivation of a large number of species in a specific geographic area. In a controlled environment, climatic conditions are optimal for certain species, regardless of the external environment (FAO 2013). Greenhouses increase crop yields by as much as four to ten times as plants grown under open field conditions; the quality of the product is normally higher than open field and the dependency on chemicals is drastically reduced. The main reasons for increased yields lie in the nature of the growing environment as well as the genetics of some greenhouse varieties. Cultivation in the open field also tend to be much easier and less costly hence production of fresh vegetables by numerous people in this system of production. In Israel, for instance, research is usually carried out in fully climate controlled greenhouse Greenhouses have been utilized in Europe, U.S.A, Canada and several other countries for many decades for improved yields (Wiltshire, 2007) and this can also be incorporated into our environment.
In agriculture, quality determination of produce is based on a multitude of features (Dull, 1986): flavour (sweetness, acidity); appearance (colour, size, shape, blemishes, glossiness); and texture (firmness, mouth feel). These features may be influenced by the system of production since crops are exposed to varied external environmental conditions.
There are many vegetable crops including pepper that are adapted in all parts of West Africa of which Ghana is no exception. Pepper in Ghana, for instance, is grown in all the ecological zones of the country; coastal savanna, rain forest up to the guinea savanna zones in the open field and green house technology is only applicable in the research
stations and the few well established farms have adopted for production of various vegetables. For each of these systems of production there are little or no records to ascertain the growth, yield and preference or the choice acceptable by the consumer.
There are climatic conditions such as prevailing high and low temperatures, energy, high or low rainfall, waterlogging, higher relative humidity and strong winds that are limiting factors for growing sweet pepper under open field. In the green house when the growth parameters are not properly regulated and these may affect the quality of fruit produced which intends to affect consumer demands and acceptance. The fruit set of pepper is greatly influenced by humidity and temperature. Low humidity and high temperatures results in poor fruit set due to dropping of flower buds, flowers and small fruits caused by their abscission because of their excessive transpiration, also night temperatures below
15.6 °C and above 32.2° C prevent fruit set (Norman (1992). According to Sinnadurai (1992), sweet pepper requires milder climate for good production unlike hot pepper that requires high temperatures and very hot weather decreases flower initiation and this affects the fruit yield. Flower production is significantly increased when the night temperatures during the growing season is between 12-21°C and fruits also develops sun scalds when grown in the dry season in the open field.
Adopting ways of increasing production of green pepper has brought to the light the use of controlled environment (green houses, poly houses etc). The greenhouse systems are important since they can be used all year round to increased yield even in the lean seasons. Nevertheless, export and local market both demand high quality sorted fruits and vegetables, which preserve their fresh condition on the market. Additionally, there is an increased demand for fruits and vegetables that are beneficial for healthy life style as well
as rich in ingredients that positively influence the prevention of any health malfunction. Since most of the agricultural products changes of inner content and outer properties after harvesting, therefore, it is crucial to determine the optimal production system that may enhance quality and acceptability of fruit by consumers or end users.
To make pepper cultivation successful and accepted by consumer’s different systems of production must be tested. Chandra et al. (2000) and Singh et al.2004 and (2010) indicated that polyhouses, poly-tunnels and plastic-mulching are most suitable solutions for yield increase of sweet pepper. Protected structures act as physical barrier and play a key role in integrated pest management by preventing spreading of insects, pests and viruses causing severe damage to the crop (Singh et al. 2003).
It is therefore imperative to note that about 95% of plants, either food crops or cash crops are grown in open field. Since time immemorial, man has learnt how to grow plants under natural environmental conditions. In some of the regions where the climatic conditions are extremely adverse and no crops can be grown, greenhouse technology is the technique of providing favourable environment condition to the plants; it is rather used to protect the plants from the adverse climatic conditions such as wind, cold, precipitation, excessive radiation, extreme temperature, insects and diseases. According to Wiltshire, (2007) greenhouses increase crop yields by as much as 4 to 10 times compared with plants grown under open field conditions. The quality of the produce from greenhouse is normally higher than open field and the dependency on chemicals is drastically reduced and this is brought about by the nature of the growing environment as well as the genetics or the type of varieties cultivated. Yield of crops may differ from the cultivar or variety used.
