EXPLOITATION OF GYNOECY IN CUCUMBER {Cucumis sativus L.)
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Date
1999-03-06
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MAHATMA PHULE KRISHI VIDYAPEETH, RAHURI - 413 722, DIST. AHMEDNAGAR, (M.S.) INDIA
Abstract
An investigation was undertaken with a view to study the parthenocarpy mechanism in Poona Khira tropical gynoecious line of cucumber, heterosis over better parent, supenority over top parent, combining ability of tropical gynoecious lines, specific combining ability of tropical gynoecious hybrids, magnitude of gene action for earhness and yield attributes and incidence of powdery mildew, downy mildew and virus diseases under natural epiphytotic conditions during Kharif91, Rabi 97 and Summer 98 seasons, to study the per se performance of selected hybrids during off-seasons under plastic greenhouse as well as in open field PKG-1-2, PKG-1-11, PKG-1-12 and PKG-1-15 (yellow fruited) and PKG-1-21, PKG-1-23 and PKG-1-24 (green fruited) lines were found to be 100 per cent parthenocarpic and homozygous for gynoecy. These lines performed better for horticultural characters in plastic greenhouse during Khanf '1998. Abstract Contd .. CD. Badgujar An appreciable amount of heterosis over better parent was observed for earhness and yield in most of hybrids. Five hybrids showed simultaneous significant heterosis for three or more characters comprising earliness and yield. These hybnds were H-13 (# 304 x Narayangaon local), H-27 (#319 x CH-2), H- 210 (# 319 x Khira-90), H-312 (# 338 x EC-173934) and H-42 (PKG lme x Himangi). In three seasons study, 13 hybnds including above top five heterotic hybrids have surpassed the top parent for three or more characters comprising earliness and yield It was evident that, among the 4 gynoecious females, # 319 combined well for more than 6 characters and # 338, PKG line and # 304 (only dunng Summer) for three or more than three earliness and yield attributing characters. Among the males Poona Khira, Sel. 75-1-10, CH-2, Himangi, Khira- 90, Raibaraili Sel. and EC-173934 exhibited high g.c.a. effects for five or more than five characters contnbutmg earliness and yield. The hybrids namely H-13, H- 210 and H-211 (for Khairfu kab^Smnmer seasons); H-15, H-26, H-27, H-36, H-312 and H-411 (for Rabi and Summer) and H-42, H-48 (for Summer) emerged as the best specific combiners. The results for gene action (all three seasons) indicated preponderance of non additive genetic variances and were more important than additive genetic variances for most of the earliness and yield attributes. The off-seasons per se performance of selected hybnds grown under plastic greenhouse and in open field indicated that, under plastic greenhouse, H- 27, H-210 and H-211 for December, however, H-13, H-312 and H-211 for April month; while m open field condition; H-13, H-312 and H-211 for December, H- 27, H-211 and H-22 for April month were found promising for earliness and yield components The incidence of powdery mildew was not recorded in parents as well as hybrids during all seasons studied. The incidence to downy mildew in parents ranged from 62.50 to 100, 30 to 70 and 20 to 60 per cent^ respectively during Kharrf 1997, Rabi 1997 and Summer 1998, respectively. The corresponding per cent disease mtensity was 17.17 to 51.98, 9.18 to 23.09 and 2.42 to 9.50 per cent,respectively In hybrids, incidence to downy mildew ranged from 60 to 100; 30 to 80 and 20 to 66.66 per cent during Kharrf 1997, Rabi 1997 and Summer 1998, respectively. The corresponding disease mtensity ranged from 21.80 to 53.34, 7.07 to 27 99 and 1.61 to 9.23 per cent, respectively. Plant infection to virus disease was not noticed in Rabi 1997. During Kharrf, Raibaraili Sel. recorded 40 per cent plant infection and H-17 and H-37 in the range of 20 to 40 per cent. In Summer, 1998; per cent plant infection to virus (CMV) was ranged from 10 to 24 in parents, however, it was 10 to 75 per cent m hybrids. The corresponding coefficient of infection were 2.5 to 40 and 2.5 to 52 per cent respectively. Considering the overall performance, it is evident that the hybrids H- 13, H-27, H-210, H-312 and H-42 had high potential for earliness and yield contributing characters for 3 seasons. Further, the hybrids H-26, H-211, H-36, H- 41 and H-411 also had high potential m respect of earliness and yield for two seasons. The prospectus of heterosis breeding were found to be promising for days to anthesis of first female flower, node of first female flower, fruits per plant, weight per fruit, total and early yield per plant and vine length. For remaining characters,the improvement could be brought b^ conventional selection procedure.
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