Effect of plant spacing and inorganic fertilizer rate on tomato seed production

Abstract

Tomato (Solanum Lycopersicum ) is rated as high market value horticultural crop in Kenya with a ready market both domestically and regionally. Moreover, tomato is among horticultural crops with great potential for improving food security and income generation among rural and urban resource poor community. Tomato seed production is becoming a major source of income for small scale farmers in Kenya. However, its productivity is low due to several factors such as, lack of use of fertilizers, poor plant stand, use of unimproved cultivars and pest and disease infestation. Nutrient management and maintenance of optimum number of plants per unit area are considered as important management tools for enhancing tomato seed production. Therefore this study was conducted to identify the optimum level of NPK (17:17:17) fertilizer and plant population that promote seed production in tomato. Field experiments using tomato cultivar Riogrande VF were conducted in October, 2015 and March, 2016 cropping seasons. The treatments consisted of three spacing; 60 cm×25 cm, 60 cm×45 cm and 60 cm×60 cm and four levels of NPK (17:17:17) fertilizers applied at : 0 kgha-1, 200 kgha-1, 300 kgha-1 and 400 kgha-1. The experimental design was complete randomized block design fitted with a split plot arrangements. The main plots were plant spacing and the subplots were fertilizer levels. Data were collected on plant height, number of leaves, number of branches, number of fruits per cluster, number of seeds per fruit, weight of 1000 seeds and seed yield per hectare. The results revealed that combination of plant spacing and NPK (17:17:17) application significantly (P≤0.05) influenced growth and seed yield of tomato. A combination of 60 cm×60 cm spacing with 400 kgha-1 NPK (17:17:17) fertilizer resulted in the highest number of leaves (55 per plant), number of branches (13 per plant), weight of seeds per fruit (9.3 g ) and seed yield per hectare (86.3 Kgha-1). This was followed by a combination of 60 cm×60 cm spacing supplied with 300 kg ha-1 NPK (17:17:17), and 60 cm×45 cm sp acing supplied with 400 kgha-1 NPK (17:17:17). A combination of 60cm×25cm spacing and 400 kgha-1 NPK (17:17:17) fertilizer resulted in the tallest plants with low seed yield compared to all other treatments. Therefore in order to realize high seed yield in tomato, a spacing of 60 cm × 60 cm with application of 400 kg ha-1 NPK (17:17:17) fertilizer should be adopted. A closer spacing of 60cm× 25cm results in taller plant that could be a disadvantage in seed production due to the possibility of lodging. In addition, this spacing resulted in the use of high quantity of seeds at planting that eventually produce low seed yield per unit area, hence increasing the cost of production.