INHERITANCE OF QUANTITATIVE AND QUALITATIVE TRAITS AND DOWNY MILDEW RESISTANCE IN CAULIFLOWER (Brassica oleracea L. var. botrytis)

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Date
2017
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CSKHPKV, Palampur
Abstract
ABSTRACT The present investigation entitled “Inheritance of quantitative and qualitative traits and downy mildew resistance in cauliflower (Brassica oleracea L. var. botrytis)” was carried out at the Experimental Farm of the Department of Vegetable Science and Floriculture, CSK HPKV Palampur to gather information on the gene effects for some quantitative and qualitative traits, to study the genetics of downy mildew resistance and its association with various traits, to study the extent of heterosis and to identify the heterotic combinations. The experimental material comprising of P1, P2, F1, F2, BC1, BC2 generations of six crosses developed by utilizing the four diverse parents viz., DPCaY-3, Palam Uphar, DPCaY-8 and DPCaY-6 were evaluated in Randomized Block Design along with standard check in three replications during rabi 2015-2016. Data were recorded on days to curd initiation, days to marketable curd maturity, plant frame (cm), plant height (cm), gross curd weight (g), marketable yield per plant (g), net curd weight (g), curd depth (cm), curd diameter (cm), curd size index (cm2), curd compactness (degree), stalk length (cm), number of leaves per plant, leaf size index (cm2), per cent marketable curds (%), harvest index (%), dry matter content (%), total soluble solids (oBrix), vitamin C (mg/100g), total sugars (%) and total phenols (mg/g). Complementary type of epistasis was recorded in most of the cross combinations for yield and its contributing traits, which indicates the importance of heterosis breeding for the improvement of yield in cauliflower. The nature and magnitude of gene effect varied with different crosses for most of the quantitative as well as qualitative traits. So, specific breeding strategy has to be adopted for a particular cross to get improvement in a particular trait. Single dominant gene was observed to govern downy mildew resistance in cauliflower. Correlation matrix revealed that plant disease index exhibited significant and positive correlation with total sugars, days to curd initiation, days to marketable curd maturity, stalk length and number of leaves per plant, whereas this association was significant and negative with vitamin C, total phenols, marketable yield per plant, net curd weight, gross curd weight, harvest index, curd diameter, curd size index, per cent marketable curds, curd depth and curd compactness. Gross curd weight, marketable yield per plant, net curd weight, curd depth, curd diameter, curd size index, curd compactness, per cent marketable curds, harvest index, vitamin C and total phenols in resistant genotypes were higher than susceptible ones. DPCaY-3 × DPCaY-6, Palam Uphar × DPCaY-6 and DPCaY-3 × DPCaY-8 were found to be the most promising heterotic combination for most of the economic traits and also showed resistance to downy mildew. On the basis of visual observations, plants producing white colour, non-ricey curds and were categorized as Type No.3 of plant type i.e. plants having long erect leaves with or without self-blanching habit and medium size curds.
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