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The present investigation aimed to assess the nature and magnitude of genetic divergence available in the Hybridization Block (E1) and National Hybridization Garden (E2) of ICAR-Sugarcane Breeding Institute, Coimbatore and to select the suitable diverse genotypes as parents for further utilization. Principal component and hierarchical cluster analyses were carried out in sixty eight genotypes with nine traits. In E1, the first three principal components explained about 73.45 per cent of the total variability and remaining six components accounted 26.55 per cent of variability. The PC 1 explained a maximum variability of 44.85 per cent followed by PC 2 and PC3. In E2, the first three principal components explained about 76.71 per cent of the total variability among the genotypes and the remaining six components described 23.29 per cent towards the total diversity. Nineteen clones viz., Co 0314, Co 8371, Co 85019, Co 86010, Co 94008, Co 98010, Co 11015, Co 12014, Co 14002, CoSnk 05103, CoV 89101, CoV 92103, CoC 671, CoT 8201 Co 1148, CoH 119, SP 80-185, ISH 100 and ISH 2 were found promising in both the environments indicating their potential to perform under varied ecological situations. Twenty clones in E1 and 38 clones in E2 can be further exploited as trait specific donors and the traits cane height, cane diameter, cane weight should be given more emphasis for further selection.

Perfect synchronization between the parental lines of Sahyadri rice hybrid viz., IR 58025A (A-line), IR 58025B (B-line) and KJTR-3 (R-line) were determined by using three methods viz., Growth duration difference, (GDD) Leaf number difference (LND) and Effective accumulated temperature (EAT). The seeding interval between A x B line was 2.66 days and between A x R was 11.89 days. The B line flowered 2.66 days before A line and R line flowered 11.89 days after A line. The Effective Accumulated temperatures (EAT) for attaining 50% flowering of A, B, & R line were 2265.91ºC, 2189.61 ºC and 2596.29 ºC respectively. The difference of EAT between A and B lines was 76.30 ºC and between A and R lines was 330.38ºC. Parental lines viz., A, B, and R lines flowered after 13.60, 12.60 and 16.70 leaves respectively. The leaf number difference between A and B lines was 1.0 leaf and between A & R line 3.2 leaves. The perfect synchronization of flowering between A and B lines can be achieved by sowing A line 3 days before second date of seeding of B line, sowing of B line after emergence of 1.0 leaf of A line and when A line reaches its EAT to 76.30 ºC. Similarly, the synchronization of flowering between A and R line can be achieved by sowing A line 12 days after second date of seeding of R line, after emergence of 3.2 leaves of R line and when R line reaches its EAT to 330.38ºC. This phenology model can be exploited for perfect synchronization of flowering in commercial seed production of A x B line and A x R line of Sahyadri rice hybrid.

Maize is the Queen of Cereals and has proven its utility as food, feed, fodder, fuel and raw materials for many industries. In order to meet the ever increasing demand of maize, the hybrid seed production plays an important role. The hybrid performance is based on its parental inbred potential and longevity. Accelerated ageing test is an efficient method to measure the seed vigour and to predict seed longevity. Single cross maize hybrids viz., CoH(M) 6, CoH(M) 8 and their parental lines viz., UMI 1200 (female parent of CoH(M) 6), UMI 1201 (female parent of CoH(M) 8) and UMI 1230 (common male parent of CoH(M) 6 and CoH(M) 8) were subjected to accelerated ageing test at 40 ± ْ 1 C and 100 per cent relative humidity for a period of 10 days. The results of the study revealed that the hybrid seeds of CoH(M) 6 maintained their viability for a longer period up to four days when compared to CoH(M) 8 which maintaining its viability up to third day of accelerated ageing as per Indian Minimum Seed Certification Standard (90 per cent germination). All the inbreds lost their viability after the first day of accelerated ageing and the rate of deterioration was higher in UMI 1230. The other parameters like seedling length (cm), dry matter production (g/10 seedlings) and vigour index decreased upon ageing and electrical conductivity (dsm-1) increased with increase in accelerated ageing periods.

Quantitative assessment of genetic divergence in 47 pigeonpea genotypes (22 B-lines and 25 R-lines) with respect to seed yield and yield components clustered them into 10 different groups. Among the ten clusters, cluster I was the largest comprising of 35 genotypes, representing collections from Andhra Pradesh, Karnataka and Bihar, while the clusters IV, V, VI, VII, VIII and X comprised of one genotype each. The distribution pattern of genotypes into different clusters revealed no parallelism between genetic and geographic diversity. An analysis of inter-cluster D2 values revealed higher divergence between cluster VIII and cluster IX, followed by cluster IX and X indicated that hybridization between parents selected from these clusters may result in maximum heterosis. Further, the results on cluster means revealed that there was no cluster with at least one genotype with all the desirable traits, indicating the need for judicious combination of all the targeted traits required hybridization between the selected genotypes from divergent clusters. In addition, number of seeds per pod, 100 seed weight, plant height, days to maturity and seed yield per plant together contributed for about 81.31 per cent of the total divergence and hence these traits to be emphasized during selection.

Quantitative assessment of genetic divergence in 47 pigeonpea genotypes (22 B-lines and 25 R-lines) with respect to seed yield and yield components clustered them into 10 different groups. Among the ten clusters, cluster I was the largest comprising of 35 genotypes, representing collections from Andhra Pradesh, Karnataka and Bihar, while the clusters IV, V, VI, VII, VIII and X comprised of one genotype each. The distribution pattern of genotypes into different clusters revealed no parallelism between genetic and geographic diversity. An analysis of inter-cluster D2 values revealed higher divergence between cluster VIII and cluster IX, followed by cluster IX and X indicated that hybridization between parents selected from these clusters may result in maximum heterosis. Further, the results on cluster means revealed that there was no cluster with at least one genotype with all the desirable traits, indicating the need for judicious combination of all the targeted traits required hybridization between the selected genotypes from divergent clusters. In addition, number of seeds per pod, 100 seed weight, plant height, days to maturity and seed yield per plant together contributed for about 81.31 per cent of the total divergence and hence these traits to be emphasized during selection. [ABSTRACT FROM AUTHOR]