Standardisation of operational procedures for pro-tray seedling production of vegetables

Abstract

Healthy seedlings are the most important prerequisite for any vegetable crop to reach its full output potential. As a result, large-scale seedling production is becoming a profession and a commercial activity. Farmers used to generate seedlings at a reasonable cost in nursery beds in the past. However, due to some drawbacks like poor germination, higher pest and disease incidence, poor field establishment etc. in traditional nurseries, many progressive farmers and agriculture entrepreneurs have turned their attention to the commercial production of quality seedlings utilising seedling trays or pro-trays. In this background, the present study entitled ‘Standardisation of operational procedures for pro-tray seedling production of vegetables’ was undertaken with the objective of standardising best growing media, pre-sowing seed invigoration, and evaluating the effect of biofertilizer on pro-tray seedling production of vegetables. The present study was carried out at the Department of Vegetable Science, College of Agriculture, Vellanikkara as three experiments during 2020-21. All three experiments were conducted in a Completely Randomized Design with three replications. In the first experiment seeds of tomato var. Anagha, chilli var. Anugraha, cucumber var. Heera, and okra var. Salkeerthi collected from the Department of Vegetable Science were sown in seventeen different media that were initially analysed for various physicochemical properties. The growth parameters of the seedlings raised in the poly house were assessed at the stage of commercial sale of each crop i.e., 15 days after sowing (DAS) in cucumber and okra and 30 DAS in chilli and tomato. The results showed that T13 (cocopeat: vermiculite: perlite - 1:1:1) and T17 recorded comparatively minimum bulk density, maximum water holding capacity and porosity which are desirable physical properties for good seedling growth. T17 (coir pith compost: vermiculite: perlite - 3:1:1) was found to be the best soil-less media for all four crops based on growth parameters and cost analysis. Among soil containing media T6 having soil and dried powdered cow dung in equal proportion and T10 having soil, cocopeat and dried cow dung exhibited a higher benefit cost ratio and was found to be on par with T17 for most of the growth parameters. Farmers do not have easy access to vermiculite and perlite, and they are costly. In this context, soil, cocopeat and dried powdered cow dung in equal proportion is found to be an alternate media comprising locally available inputs and affordable by the farmers. The best media from the first experiment was chosen for further trials. The second trial comprised of nine different seed treatments including various concentrations of KNO3 and Pseudomonas. Pre-sowing seed invigoration with 0.5% KNO3 in combination with 1% Pseudomonas was found to be highly effective in improving germination and growth parameters viz., germination percentage, plant height, root length, vigour index Ⅰ & Ⅱ and chlorophyll content of seedlings of tomato, chilli, cucumber and okra. This combination has the dual advantage of providing potassium and nitrogen to the seedlings and imparting resistance from diseases especially damping off. So, these treatments can be effectively utilized for producing healthy and vigorous vegetable seedlings. The third experiment included nine treatments in which different biofertilizers viz., PGPR Mix-1, Pseudomonas fluorescense, Trichoderma asperellum and arbuscular mycorrhizal fungi were inoculated in the media individually and in combination. Evaluation of the effect of biofertilizers showed that higher growth parameters like plant height, root length, leaf area, collar girth, vigour index Ⅰ and vigour index Ⅱ are comparatively higher in the treatment containing PGPR, AMF and along with either Pseudomonas or Trichoderma. In the above three experiments the best treatments were identified by ranking based on an index derived from principal component analysis. The characters viz., number of leaves, leaf area, collar girth, vigour index Ⅰ & Ⅱ and total chlorophyll content was used for performing PCA. The loadings of principal component having Eigen value more than one was taken as weightage. Using weightage, an index was derived and the treatments having higher index was ranked higher. The best media obtained include cocopeat: vermiculite: perlite (3:1:1) and soil: cocopeat: cow dung (1:1:1). A combination of 0.5% KNO3 and 1% Pseudomonas was the best seed invigoration treatment. Among different biofertilizers evaluated the combination of AMF, PGPR Mix-1 and Pseudomonas was found to be the best. Based on the insights of the above three trials, standard operational protocol for seedling production of tomato, chilli, cucumber and okra is generated for use by farmers.