Performance of commercial vegetable crops under naturally ventilated protected cultivation structure in saline environments

Abstract

The most of vegetables are low gestation period and high income generating crops. Many vegetables are now grown under protected structures in off-season to fetch remunerative prices. However, meager information is available regarding the performance of vegetable crops under salinity in protected cultivation. Therefore, a study has been started with three vegetable crops; capsicum (var. Indra), hot chilli (var. Kranti) and tomato (var. Cibelia) to evaluate the effects of saline irrigation on their productivity, profitability and sustainability under a low cost, naturally ventilated polyhouse structure. There were six saline water treatments including the best available water (BAW). Capsicum and chilli were transplanted on 04 August 2015 and tomato on 26 August 2015. After the initial establishment period of 15 days, saline water treatments were initiated. The vegetables were grown on 15 cm high raised beds at 45 cm x 30 cm spacing. Saline water was applied using drip system under gravity flow. The recommended dose of water soluble fertilizers was mixed with the irrigation water. Results of the first year study showed good response of crops even under high salinity treatments. The highest fruit yield (63 t ha-1) of capsicum was obtained with BAW. Only slight reduction in capsicum yield was noted with increasing salinity in irrigation water; capsicum yield was 62.2 t ha-1 at ECiw 6 dS m-1 and 58.2 t ha-1 at 8 dS m-1. Similarly, the highest fruit yield (48.5 t ha-1) in chilli was obtained under ECiw of 6 dS m-1 followed by ECiw 10 dS m-1 (45.7 t ha-1) and ECiw 4 dS m-1 (45.2 t ha-1). The highest fruit yield (116.2 t ha-1) of tomato was obtained at ECiw of 6 dS m-1 followed by ECiw 10 dS m-1 (111.0 t ha-1) and ECiw 4 dS m-1 (111.0 t ha-1). Harvesting in all the three crops was staggered over months (capsicum 15 pickings; chilli 13 pickings; and tomato 28 pickings) indicating that high and consistent fruit yields can be obtained with the use of saline water under improved management practices. Studies are underway to assess the impacts of continued irrigation with saline water on soil properties and practices such as leaching with the harvested rainwater to overcome the rootzone salinity.