An investigation to optimize the protocol for application of colchicine for enhancing the doubled haploid production in maize was done. 106 maize genotypes were used as maternal parents, whereas, pollen source involved tropically adopted haploid inducer (TAIL P1 and TAIL hybrid). After the elimination of chromosomes of inducer lines, haploid seeds were obtained from the crosses. Haploid seedlings were treated with three different doses, such as 0.04, 0.06 and 0.08 per cent of colchicines for different durations (8, 12 and 15 hours). The response of various colchicine concentrations applied for different time durations revealed significant differences at P ≤ 0.05 for various parameters viz., per cent plants survivability, stalk colour, the fertility of tassel, silk present/absent, pollen viability, seed set and per cent doubled haploid formation. In maize, colchicine doses of 0.04 per cent for 12 hours and 0.06 per cent for 8 hours, respectively were established as optimum for enhanced doubled haploid production. But among these two, 0.04 per cent for 12 hours was observed to be best dose for doubled haploid production in maize.

Twenty five CIMMYT inbreds were crossed with four elite tropical maize testers. Results exhibited that one inbred line tester can select the top best lines from a large number of CIMMYT lines and two testers gave more reliable results than one tester did. However, when line × environment interaction was significant, selected lines by one tester in one environment were not necessarily same as those selected at another environment indicating thereby that different testers should be used for selecting best inbreds at different environments. This study also showed that inbred lines from different maize heterotic groups did not show any significant differences in identifying best CIMMYT germplasm.

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.

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Experimental material consisted of 25 lines, 2 testers and their 50 crosses along with standard checks viz., Palam Sankar Makka-2 and PSCL 4640 were evaluated using Randomized Block Design with two replication during Kharif 2020. Genotype mean square was significant for days to 50% tasseling, days to 50% silking, days to 75% brown husk, ear height (cm), plant height (cm), ear length (cm), ear circumference (cm), kernel rows/cob, kernels/row, 1000-kernel weight (g), shelling (%) and grain yield (q/ha) which indicated the presence of sufficient genetic variability in the material studied. Also the ratio of GCA variance to SCA variance was less than unity for all traits indicated preponderance of non-additive gene action. Among lines, KI-3 exhibited higher grain yield followed by KI-7 and CML 140. These lines also exhibited highest significant GCA effect for grain yield and were identified as promising parents.