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The objectives of this study were to assess and identify new source of phenotypic variability among F3 and BC1F2 tomato populations, and apply genotype by yield*trait (GYT) biplots for population and line selection based on multiple traits. Four diverse cultivated parents (‘CLN2498D’ [D] and ‘CLN2417H’ [H] from Ethiopia; ‘UC Dan INDIA’ [U] and ‘Tima’ [T] from Nigeria), and wild parent ‘LA2093’ [W] were used to generate 276 potential breeding lines. The lines were categorized into eight populations (‘pop_1_W/H1’, ‘pop_2_W/H2’, ‘pop_3_W/D1’, ‘pop_4_W/D2’, ‘pop_5_W/T1’, ‘pop_6_W/T2’, ‘pop_7_W/U1’, and ‘pop_8_W/U2’), and evaluated twice in the field using 19 × 15 alpha-lattice design with two replicates. Significant differences were observed among lines and populations for all yield enhancing traits. ‘Pop_1_W/H1’, ‘pop_4_W/D2’ and ‘pop_6_W/T2’ expressed the highest genetic divergence for plant height, number of leaves, total flower and fruit number, and fruit weight. GYT biplots revealed that all yield*trait interactions had a positive correlation with each other. F3 populations, ‘pop_5_W/T1’ and ‘pop_1_W/H1’ exhibited the best performance for majority of the yield*trait combinations. Hierarchical clustering on principal components (HCPC) revealed overlapping lines (70.58% of Cluster D lines) and (54.05% of Cluster U lines) from the two F3 populations. In BC1F2 population, 32.35% of the 34 original lines of Cluster D and 48.48% of Cluster T lines overlapped between Clusters D and T, while 18.18% of Cluster T lines and 8.82% of Cluster H lines were transgressive between Clusters T and H. Transgressive segregants ‘0210U1’, ‘0211U1’, and ‘0171T1’ of selfed population using multivariate analysis were believed to represent potential sources of novel genetic variation for future tomato breeding.

High humidity is a major constraint to increased tomato fruit production in a cool tropical monsoon climate. However, the genetic variation observed in Solanum pimpinellifolium makes it a good gene donor for breeding tomato cultivars capable of thriving under high humidity. The objective of this study was to estimate heterosis, heritability for higher yield, and to assess the adaptability of the genotypes to humid conditions. Genotypes were raised from five morphologically divergent parents, viz., wild parent (W)–“LA2093,” “CLN2498D” (D), “CLN2417H” (H), “Tima” (T), and “UC Dan INDIA” (U). The F1s were generated by biparental mating design using “LA2093” as a common pollen donor that was selfed to produce F2s and backcrossed to both parents to obtain BC1s and BC2s. The trial was laid out in a randomized complete block design with three replicates. Data were collected on selected yield-influencing traits and analyzed. “D × W” and “U × W” hybrids showed significant positive better parent heterosis for fruit weight per plant (30.4% and 35.5%) and total fruit yield (48.6% and 26.9%), respectively. The additive variance was higher than dominance variance for all the traits, including total fruit yield in all hybrids viz., “H × W,” “D × W,” “T × W,” and “U × W.” High narrow sense heritability estimate of ≥60% was observed in “D × W” and “U × W” hybrids for the majority of the floral and fruit traits including total fruit yield. This makes the improvement of “D × W” and “U × W” hybrids by direct selection advantageous. Hence, the adoption of selection for the affected traits in subsequent tomato breeding programs would enhance fruit yield and adaptability to humid environments.

The objective of this work was to evaluate four parental lines of cucumber which included: ‘Zeina’ (Zna), ‘Beit Alpha’ (BA), ‘Straight 8’ (Strght 8) and ‘Calypso’ (Capso) and six F1s generated by diallel cross, using randomized complete block design with three replications to study heterosis and combining ability for yield and yield component traits. Estimated heterosis showed that cross ‘Zna × Capso’ had the highest Better Parent (BP) heterosis in total fruit yield/ha while ‘BA × Capso’ had the highest Mid Parent (MP) heterosis in the same trait. Significant general (GCA) and specific (SCA) combining ability variances were obtained in all the traits implying that both the additive and non-additive gene effects operated in the genetic expression of the traits. Relative magnitude of GCA and SCA variances indicated preponderance of additive gene action for all the traits. ‘Beit Alpha’ and ‘Straight 8’ are best general combiners while ‘BA × Capso’ and ‘Capso × Strght 8’ were the best specific combiners for total fruit yield. Keywords: Cucumber, Hybrid vigour, Half diallel crosses, GCA, SCA