http://www.erepo.iihr.ernet.in/handle/123456789/336 2013-05-15T21:47:20Z http://www.erepo.iihr.ernet.in/handle/123456789/404 Title: Isolation of resistance source for combined diseases viz., purple blotch, basal rot and white rot in onion (Allium cepa L.) by saprophytic and gametophytic screening Authors: Ambresh Abstract: Onion is an important vegetable crop grown in India and throughout the world. Purple blotch caused by Alternaria porri is one among serious fungal diseases that affect onion, causing heavy yield loss ranging from 2.5 to 87.8 per cent. So there is need to develop hybrids with male sterility background for resistant to purple blotch disease coupled with higher yield. Twenty eight crosses resulting from a L x T design comprising of four lines and seven testers were studied to know the combining ability and magnitude of heterosis. Combining ability analysis revealed that L3 showed good general combiner for most of the characters. The tester T4 and T5 were identified as good general combiner for yield and yield attributing characters. Among the 28 crosses, L2 x T4 was identified as best specific combiner as it showed high sca effect and per se performance, were as cross L3 x T5 exhibited high per se performance for total and marketable bulb yield. For heterosis out of 28 crosses, L2 x T4 and L3 x T5 were the most heterotic and could be exploited for commercial cultivation. The cross L2 x T4 (-42.62%) had exhibited highest magnitude of heterosis over commercial check for purple blotch disease resistance in desired direction. L2 x T1 (-7.78%) exhibited significant stranded heterosis for days to maturity. L3 x T1 (36.84%) showed significant mid parent heterosis for ten bulb weight. The cross L3 x T5 exhibited highest magnitude of heterosis over commercial check for total bulb yield tonnes per hectare (27.44%) and for marketable bulb yield per hectare (28.65%), L2 x T2 (-33.33%) exhibited significant heterosis over standard check for unmarketable bulb yield per hectare. 2002-01-01T00:00:00Z http://www.erepo.iihr.ernet.in/handle/123456789/403 Title: Studies on heat tolerance in garden pea (Pisum satvum L.) Authors: Oinam Kumar Singh Abstract: Twelve garden pea lines viz., UN-5-29(P), IHR575, UN-5-29(S), RPN-34, IHR-544, RPD-9-1 (P), UN-57(G),RPD-9-1(S) (early lines), IHR-476, Bonneville, FC-1-32-1-1-40 and IHR-570 (mid season lines) were evaluated for growth and yield parameters during rabi and summer seasons and the relative performance of the lines at high temperature, its effect on yield and yield components and the role of chemical constituents in offering heat tolerance were studied. High temperature was found to affect the growth and consequently the yield during the summer season. All the growth and yield parameters decreased drastically when the growing temperature reached 35 °C at maximum and 17 °C at minimum. At this temperature shelling percentage increased in the case of early lines but decreased in the mid season lines. Number of days taken for 1st flowering was reduced in the early lines whereas it increased in the mid season lines at high temperatures. Chemical constituents such as starch, protein and sugar also decreased during summer to the extent of 2.02 to 48.09%. Both positive as well as negative significant correlations were found among many of the characters during summer than rabi. In general, there was genotypic variation in heat tolerance in garden pea lines. Lines with long duration had less tolerance to heat as compared to short duration lines. Chemical constituents of the plants were also altered by temperature with wide variations among the lines. Among the lines tested, IHR-544 and IHR-575 were found to be the most heat tolerant lines and were most suitable for cultivation during the summer season. 1991-01-01T00:00:00Z http://www.erepo.iihr.ernet.in/handle/123456789/402 Title: Variability, heritability, correlations and path analysis in carrot (Daucus carota L.) Authors: B N, Nagaraja Abstract: Thirty nine genotypes of carrot representing the collections from diverse geographic area of the world were studies for variability, heritability, correlations and path analysis. Significant differences were observed for all the 17 characters studies. The PVC and GCV values were larger for specific leaf area, specific leaf dry weight, fresh weight of leaves, dry weight of leaves, fresh weight of roots, carotene content, percent forked roots and undersized roots. However, these PVC and GCV values were lower for rest of the traits. High heritability values associated with high genetic advance was observed for carotene content, root yield, fresh leaf weight, dry leaf weight, fresh weight of roots and specific leaf area, which indicated that selection for these characters will be effective. Rest of the characters had moderate or low heritability. The genotypes IHR 3, IHR 75, IHR 128 and IHR 205 exhibited deep orange colour of roots and these had high carotene content. Root yield was positively correlated with root length, root diameter, top length, fresh weight of roots, number of leave, fresh weight of leaves, dry weight of leaves, specific leaf of area and carotene content. Path analysis studies revealed that among the components characters, diameter of root exerted maximum positive effect on root yield both directly and also indirectly through traits like top length, specific leaf area and number of leaves. 1988-01-01T00:00:00Z http://www.erepo.iihr.ernet.in/handle/123456789/401 Title: Genetic analysis for chilli veinal mottle virus resistance in chilli (Capsicum annuum L.) Authors: M S, Adarsha Abstract: Though India is the largest producer of chilli in the world covering an area of 8.922 lakh ha, its production (9.213 lakh t) and productivity (1030 kg/ha dry yield) are considerably low. Among the factors that limit its production, viruses play an important role. Around 21 viruses are reported to be affecting chilli in India, of which chilli veinal mottle virus (ChiVMV) and cucumber mosaic virus (CMV) transmitted mechanically and aphids in non-persistent manner are very important. In India cultivars with good amount of potyvirus resistance coupled with high yielding potential are lacking in chilli. A few varieties viz., Pant C-1, Tiwari, Punjab Lal are developed for virus resistance, their acceptability in the country is limited. Therefore, a few experiments were conducted to confirm resistance to ChiVMV in the improved lines at IIHR, to study genetics of resistance to ChiVMV resistance; and to study heterosis, combining ability and gene action of the hybrids developed using promising ChiVMV resistant lines. Segregation patterns for disease reaction in F1, F2 and backcross generations along with their corresponding parents suggested monogenic recessive condition for ChiVMV resistance. Heterosis study indicated the superiority of some out standing hybrids over better parent. Combining ability studies indicated that both gca and sca effects were important for all the characters studied, however the gca variance was lesser than the sca variance expressing the non-additivity preponderance. Parents with high mean performance and significantly desired effects along with F1s having significantly desired sca effects have been pooled. The gene action study illustrated that the characters viz., number of secondary branches per primary branch, average fruit weight, stalk length, fruit width and ChiVMV resistance were under control of both additive and non-additive effects. Epistasis was operating in few traits viz., early flowering, plant height, plant spread, fruit width and seed ratio per fruit. Fruit length was under the control of additive gene action. 2004-01-01T00:00:00Z