Effect of plant spacing and nutrient source on growth and yield of pineapple (Ananas comosus) in Wakiso district
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Uganda produces only 0.35% of total pineapple production for East Africa compared to 80% and over 19% produced in Kenya and Tanzania, respectively. Low productivity is attributed to lack of improved planting materials, high fruit perishability, low fruit prices, lack of access to formal credit, plant diseases and soil nutrient depletion. Nutrient depletion in Uganda is estimated at 66 kg ha-1 per annum. As a result, farmers obtain low crop yields and experience crop failure. This study was conducted to evaluate the effects of nutrient source and spacing on growth rate and yield in pineapple. Field trials were set-up at the National Crop Resources Research Institute (NaCRRI), Namulonge using a split-plot design. Nutrient source was the main factor, with two treatments: NPK (3kg/150m2) and poultry manure (100kg/150m2). Plant spacing was the sub-factor at 0.5ft, 1ft, 1.5ft and 2ft between plants in a double row; each treatment having three replicates. Data were taken monthly on ten randomly selected plants. Growth rate was determined as plant height and width, leaf length and width. Yield was determined from fruit number and average fruit weight per 15m2 for spacing and 150m2 for nutrient source. Nutrient source had a significant difference (P<0.05) on plant height, plant width, leaf length and leaf width. Poultry manure produced the tallest (25.4cm) and widest plants (94.2cm), the broadest (4.4cm) and longest leaves (62.7 cm) while control produced the shortest plants (23.5 cm); NPK produced the narrowest plants (87.9cm) with the shortest leaves (59.4cm). Nutrient source showed no significant effect on average fruit weight and number of fruits. There were significant differences (P< 0.05) between plants in plant height and width, leaf length and leaf width at different spacing. The tallest (25.6cm) and widest plants (94.3cm), with the broadest (4.5cm) and longest leaves (62.4cm) were produced at 1.5ft plant spacing. In contrast, 0.5ft plant spacing produced the shortest (22.7 cm) and narrowest plants (86.2cm), with the narrowest (3.99cm) and shortest leaves (59.7cm). This spacing, however, produced the most number of fruits (76) although with the lowest average fruit weight (950g). The lowest number of fruits (21) was recorded at 2ft. spacing. The highest mean fruit weight of 1384g was realized at the 1.5ft spacing. The highest overall yield (47.4 tons/ha) was recorded at a spacing of 1ft. Controlled studies are recommended for different agro-ecological regions where pineapple is grown in Uganda in addition to profitability analysis for recommended plant spacing (0.5ft and 1ft) and nutrient source (poultry manure).