Heterosis breeding exploiting gynoecy in cucumber (Cucumis sativus L)

Abstract

The present study ‘Heterosis breeding exploiting gynoecy in cucumber (Cucumis sativus L.)' was carried out at Department of Olericulture, College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during February-May 2012 and November 2012 to March 2013 to study the combining ability of gynoecious line with selected monoecious lines in cucumber and to investigate the scope of heterosis breeding exploiting gynoecious line. Twelve monoecious cucumber genotypes were collected from different parts of the country and was crossed in a topcross manner with a stable gynoecious inbred introduced from USA (EC 709119) as female parent. Observations on important 15 quantitative characters and 10 qualitative characters were recorded in five randomly selected plants. The F1 hybrids along with their parents were evaluated to obtain information on combining ability and heterosis. In this experiment, maleness was successfully induced in the gynoecious line (EC 709119) by spraying silver thiosulphate @ 200 ppm. The male flowers produced were uniform and normal as monoecious cultivars with high pollen fertility. Inspite of the temperate origin, the gynoecious character was stable throughout the life span. The data were subjected to combining ability analysis according to top cross method. Significant GCA effects were observed for all the characters except days to first male flower anthesis. Among 12 parents, CS-123 was observed as the good general combiner for fruit yield per vine, length of main vine, branches per plant, number of harvests, duration of the crop, fruits per plant and number of seeds per fruit. Heterosis values were estimated over mid, better and standard parents. Significant heterosis was observed for all the characters studied except average fruit weight. Almost all the hybrids produced significantly higher number of fruits per plant which contributed to increase in total yield. For vegetative characters and yield contributing characters like vine length, number of branches, number of fruits and number of harvests, EC 709119 x CS-123 was proved to be the best cross. The next best crosses with respect to quantitative characters were EC 709119 x IC 410638, EC 709119 x IC 410617 and EC 709119 x IC 538155). The performance of these hybrids with respect to qualitative characters viz, free from bitterness and crispness was also good. Hence, these hybrids can be advanced for testing under different agroclimatic conditions for commercial exploitation of hybrid vigour.