1 Assistant Professor (e mail: rss_33044@hotmail.com), 2 Research Assosiate (e mail: drvipin_81@rediff.com), 3 Professor (e mail: raina_jn@yahoo.com), Department of Soil Science and Water Management, 4 Associate Professor (e mail: rameshkbhardwaj @rediff.com), Department of Vegetable Science Capsicum is one of the most important nutritious and highly remunerative vegetable crops grown for its fruits. Nowadays, different coloured hybrids are available but yellow and red fetch higher price in the market. It is not possible to obtain higher yields of good quality fruits (green or coloured) under open conditions and therefore protected cultivation offers good scope for year round and also off season production of coloured capsicum. In protected cultivation, pruning and plant density are very important for optimization of plant number per unit area. Plant density and arrangement have a pronounced influence on development, growth and marketable yield of many vegetable crops. Trellising/pruning the plants facilitate easy operations and also permit closer planting and get higher yields of larger sized fruits. The need for having appropriate plant densities in order to boost-up the production per unit area by utilizing the available space and nutrient applied is also very important in protected cultivation. There are many studies on plant density for different types of pepper (Cebula 1995, Jolliffe and Gaye 1995). Plant density and arrangement have a pronounced influence on plant development, growth and marketable yield of Indian Journal of Agricultural Sciences 84 (6): 742–5, June 2014/Article Growth, yield and economics of greenhouse grown coloured capsicum as influenced by trellis system and plant spacing R S SPEHIA 1 , VIPIN SHARMA 2 , J N RAINA 3 and R K BHARDWAJ 4 Dr Y S Parmar University of Horticulture and Forestry, Nauni, Himachal Pradesh 173 230 Received: 25 May 2012; Revised accepted: 20 March 2014 ABSTRACT The experiment was laid out in split plot design and the treatments comprised V trellis with two stems (T 1 ), V trellis with four stems (T 2 ) and Spanish trellis (T 3 ) as main plot along with three plant spacing levels, viz. S 1 (40 cm × 40 cm), S 2 (60 cm × 40 cm) and S 3 (60 cm × 60 cm) as sub plot treatments. Results of the study showed that plant height was significantly affected by trellis, spacing and their interactions. Number of fruits/plant was highest under Spanish trellis and wider spacing (S 3 ). Fruit weight, yield/plant and yield/square meter were observed to be significantly higher under V trellis with two and four stems as compared to Spanish trellis. Plant spacing also influenced these parameters significantly and although fruit weight and yield/plant were higher in wider spacing treatment (S 3 ), yield per square meter was significantly higher in close spacing (S 1 ). Economic analysis indicated that V trellis with four stems at 40 cm×40 cm spacing is optimum for more income per rupee invested for greenhouse cultivation of coloured capsicum. Key words: Benefit cost ratio, Capsicum, Fruit weight, Spacing, Trellis, Yield per plant, Yield per square meter 74 many vegetable crops (Stoffela and Bryan 1988). A number of studies have indicated a linear increase in fruit yield when plant density is increased (Motsenbocker 1996, Stoffela and Bryan 1988, Decoteau and Graham 1994) and the increase in yield with higher plant density was a result of increased number of fruits per unit area. Although, some information on plant density of capsicum in open field condition is available, studies on greenhouse production are limited. The optimization of plant and shoot spacing in greenhouse production of bell pepper was investigated by Cebula (1995), plants were trained to two shoots and the spacing of plants was 80 cm × 30 cm. As the area under protected cultivation is growing at considerable pace, farmers are still groping in dark about the proper training/ pruning practice for getting maximum benefits under greenhouses. The present study was therefore carried out to determine the optimum plant density and trellis system for capsicum grown in greenhouses. MATERIALS AND METHODS The studies were carried out in the polyhouse at the Experimental Farm, Department of Soil Science and Water Management, Dr Y S Parmar University of Horticulture and Forestry, Nauni, Himachal Pradesh. The farm lies at 30 o 50’30" N latitude and 77 o 08’30"E longitude and located at an elevation of 1150 m AMSL. The growing media was prepared by mixing farmyard manure in the soil @ 50 kg/ m 2 and exhibited slightly acidic reaction, low salt