No abstract

The present investigation was undertaken to study the effect of non particulate gamma radiation and EMS mutagens on linseed varieties viz., Baner, Him Alsi-2 and Surbhi. Many significant effects of EMS concentration and gamma rays dosages on seed germination were observed. The percent germination was reduced from 84, 86 and 80 to 65, 58 and 59 percent with 60 kR (kilo Roentgen) for cultivars Baner, Him Alsi-2 and Surbhi respectively. LD 50 concentration of gamma rays varies in different varieties viz., 96.63 kR (Baner), 72.94 kR (Him Alsi-2-and 53.22 kR (Surbhi). The percent germination was reduced from 87, 94 and 79 to 49, 50 and 10 percent with 0.8 percent EMS for cultivars Baner, Him Alsi-2 and Surbhi respectively. Also, lethality (LD 50 ) of EMS between varieties varies i.e., Baner (0.86%), Him Alsi-2 (0.72%) and Surbhi (0.35%) showing that lethality depends upon the characteristics of seed. Variable effects were observed in field condition for seed germination and survival in all the varieties indicating that these mutagens can be used in improvement of particular characteristics of crop by following proper selection methods.

Early blight of potato caused by species of Alternaria is one of the most important diseases of potato worldwide. The occurrence of A. solani and A. alternata varies from region to region. The samples were collected from Himachal Pradesh, Uttar Pradesh and Madhya Pradesh states of India during 2009 and 2010. The identity of all the isolates was confirmed as A. alternata by morphological characters and sequencing. PCR amplification using universal primers ITS 4 and ITS 5 resulted in an amplicon of 594 bp which showed high similarity with reference ITS sequences of A. alternata in GenBank. Analysis of sequences revealed presence of partial sequence of ITS 1 and ITS 2 and complete sequence of 5.8S rRNA gene. All the isolates of A. alternata showed 100% similarity among themselves (except ALT 43) and with other A. alternata isolates in the GenBank. Three major clusters each were obtained when isolates were genotyped for RAPD and for AFLP markers. Pathogenicity was proved by detached leaf inoculation method and all the isolates were found pathogenic with varying degree of aggressiveness. Isolates were grouped into four groups on the basis of aggressiveness. No correlation was observed between aggressiveness and the clusters made on the basis of genotyping.

Background: Seed yield is a very important trait for selection but shows low heritability and hence is difficult to improve. Since the productivity of linseed (Linum usitatissimum L.) in India as well as Himachal Pradesh is low in comparison to other major linseed growing countries and states, improvement in cultivars for grain yield is a must. Therefore, the present study was aimed for studying the character associations in linseed genotypes for seed yield over locations. Method: The experiment was conducted during rabi 2019-2020. The experimental material for the present investigation comprised of 52 linseed genotypes grown over three locations in Himachal Pradesh i.e. Linseed Experimental Farm, CSK HPKV, Palampur (1290 m amsl), Shivalik Agricultural Research and Extension Centre, Kangra (700 m amsl) and Hill Agricultural Research and Extension Centre, Dhaulakuan (468 m amsl). Randomized block design with three replications was used. Phenotypic and genotypic correlation coefficients were worked out as per the procedure outlined by Burton and De Vane (1953) and Johnson et al. (1955). Direct and indirect effects of component traits on grain yield were worked out using correlation coefficient of various traits as suggested by Wright (1921) and elaborated by Dewey and Lu (1959). Result: Correlation studies indicated highly significant positive correlation for seed yield with 1000 seed weight (0.965**) followed by harvest index (0.801**), secondary branches (0.585**) and a significant correlation with biological yield (0.269**). Seed yield exhibited a non-significant positive correlation with seeds per capsule. However, a negative significant correlation was observed for seed yield with days to 50 per cent flowering and number of primary branches. The path coefficient analysis indicated that 1000 seed weight exhibited maximum positive direct effect with seed yield (0.741) while others had a low direct effect. The significant positive correlation of number of secondary branches and harvest index with seed yield was mainly due to indirect effect via 1000 seed weight indicating that 1000 seed weight is the most important trait for the improvement of grain yield in linseed as per the present study.