Abdul Vahab, MBindukala, A RKAU2020-11-122020-11-122000171675https://krishikosh.egranth.ac.in/handle/1/5810154953MScThe present investigation on "Standardisation of population density in watermelon [Citrullus lanatus (Thimb.) mansf.]" was conducted at the Instructional Farm, College of Agriculture, Vellayani, Thiruvananthapuram during February - May, 1999 .. Three watermelon varieties viz., Sugar Baby, Arka Manik and MHW -6 were tried under six population densities to find out their direct and indirect effects on vegetative yield and quality attributes in watermelon. Majority of the characters were significantly influenced by the direct as well as interaction effects of the population density and varieties. Among the varieties, Arka Manik was earlier for male and female flower opening and for days' to first harvest. However, the node to first female flower was in Sugar Baby which also had more female flowers planr". The population density significantly influenced majority of the vegetative characters. Lower to moderate population density had shorter crop duration, branches planr ' and vine length. Different density levels significantly influenced the yield characters. Total fruits planr ', Total fruits plor ', Marketable fruits planr", 2 Marketable fruits plor ' ,Marketable yield plant"! were maximum in plants grown at highest density of 10000 plants ha". The variety Sugar Baby was first in all these yield characters. Sugar Baby also had the highest values for diameter, flesh thickness, rind thickness, fruit girth and seeds fruir '. The hybrid MHW-6 had maximum average fruit weight, fruit length and 100 seed weight. Among the quality parameters, Sugar Baby had maximum values for total sugars and reducing sugars whereas, Arka Manik recorded the highest values for total soluble solids, non-reducing sugars and iron content. The plants at moderate spacings recorded highest values for the quality characters. Majority of the characters were influenced by the interaction of population densities and varieties also. Sugar Baby at a moderate population density of 3333 plants ha! had maximum branches plant"! .. The number of fruits plor ' was highest in Sugar Baby at the highest population of 10000 plants ha:". This treatment combination also had maximum marketable yield plor ' registering maximum yield of 55 t ha! and maximum income of Rs. 165000 with the highest bene:{it cost ratio of 3.00 : 1.00.EnglishThesis