MSc.

A research project entitled “Response of papaya to organic manures, plant growth promoting microorganisms and mulching” was conducted in the Department of Pomology and Floriculture, College of Horticulture, Vellanikkara during 2008-2010. Major objectives were to study the response of organic manures, plant growth promoting microorganisms on growth, yield and quality of papaya, under humid tropical climate. Selection of ecofriendly mulch for papaya was also aimed as it saves water and reduces weed growth. Papaya variety CO 7 was used for the investigation. The study consisted of two field experiments, laid out in RBD with three replications in each experiment. Experiment I included 12 treatments which were combinations of organic manures and plant growth promoting microorganisms along with inorganic fertilizers. In Experiment II effect of different mulches on growth, yield and quality of papaya, soil moisture retention and weed growth was studied. There were seven treatments in experiment II which included six types of mulches.
The study revealed that application of RDF (240:240:480 g NPK/plant/year) + vermicompost (13 kg) + plant growth promoting microorganisms, viz; Trichoderma and Pseudomonas (5 g and 10 g/plant respectively) exhibited superiority in terms of vegetative and floral characters and recorded highest fruit yield (42.59 kg/plant). Application of RDF + poultry manure (10 kg/plant) + plant growth promoting microorganisms were also found superior with respect to growth and yield attributes. Quality of the fruits in terms of TSS, total sugars, acidity, overall acceptability and shelf life was highest in organic treatments where as fruit yield per plant was found lowest in these treatments.
Soil properties like pH, organic matter, available N, P and K were found to be improved by application of organic manures. Application of plant growth promoting microorganisms enhanced the microbial population (bacteria, fungi and actinomycetes) in the soil. Population of Trichoderma spp. and Pseudomonas fluorescens was also increased. Regarding the cost of cultivation, application of biovermi incurred highest cost per ha.
In Experiment II, plants mulched with biodegradable polythene and black polythene mulches showed positive response with regard to vegetative and floral characters and recorded highest fruit yield (40.99 and 40.76 kg/plant respectively). Quality attributes of the fruits were also found to improve in these treatments. The polythene mulches showed superiority in terms of soil moisture retention and it reduced the number of irrigation. Significant reduction in weed growth was also noticed in the plots mulched with polythene mulches. Soil nutrient status was improved and was superior in the treatments mulched with organic mulches. With respect to cost of cultivation also treatments T6 and T7 were superior.
Over all assessment indicated that application of RDF (240:240:480 g of NPK) + vermicompost (13 kg) + Trichoderma (5 g) + Pseudomonas (10 g) was highly beneficial for growth, yield and quality improvement in papaya. Similarly mulching with biodegradable polythene was proved to be good as it was effective in weed control, soil moisture retention, thereby improving the growth, yield and quality of papaya and it is also ecofriendly.