Exploitation of heterosis for yield and quality traits in cucumber (Cucumis sativus L.)

Introduction

Cucumber (Cucumis sativus L.) is an important warm-season vegetable crop belonging to the family Cucurbitaceae and is widely cultivated in tropical and subtropical regions owing to its high economic value, short crop duration and wider adaptability. India is considered one of the primary centres of origin (De Candolle, 1883) [5] and possesses considerable genetic diversity, providing ample scope for genetic improvement. The tender fruits are consumed fresh, cooked or processed into pickles and are valued for their high moisture, vitamins and mineral content. Cucumber exhibits considerable genetic variability and is highly amenable to hybrid breeding due to its monoecious flowering habit, large flowers, high fruit set and abundant seed production. The increasing demand for early, uniform and high-yielding hybrids has enhanced the importance of heterosis breeding in cucumber. However, productivity is often constrained by the cultivation of low-yielding cultivars, genetic impurities, variations in fruiting behaviour and susceptibility to pests and diseases. Hence, development of superior hybrids with desirable earliness, yield and quality remains an important objective of cucumber breeding programmes. Heterosis breeding is an effective approach for exploiting genetic variability and improving economically important traits. Hayes and Jones (1916) [7] were the first to report heterosis in cucumber. It refers to the superior performance of F₁ hybrids over their parents for one or more desirable traits. The magnitude of heterosis varies with parental combinations; therefore, evaluation of diverse parents and their hybrids is essential for identifying superior cross combinations. Estimation of heterosis over the better parent, commercial check and standard check provides useful information for identifying hybrids with commercial potential.

Therefore, the present investigation was undertaken to estimate heterosis for growth, earliness, yield and quality traits in cucumber using 28 F₁ hybrids, with the objective of identifying superior heterotic hybrids for commercial exploitation and future cucumber breeding programmes.

Materials and Methods

The present investigation was conducted during late kharif 2025 and summer 2026 at the Vegetable Unit, Department of Horticulture, College of Agriculture, University of Agricultural Sciences, Dharwad, Karnataka, India. Eight diverse parental lines, namely Swarna Sheetal (P₁), Himangi (P₂), Poinsette (P₃), Belagavi Local (P₄), Swarna Ageti (P₅), Dharwad Local (P₆), Arka Veera (P₇) and Nethra (P₈), were crossed in a half-diallel mating design excluding reciprocals to generate 28 F₁ hybrids. The experimental material comprising 28 F₁ hybrids, eight parents, one commercial check (Rayanna) and one standard check (Kashi Nutan) was evaluated during summer 2026 in a randomized block design with two replications. Each experimental unit consisted of a single row accommodating 10 plants at a spacing of 1.5 m x 0.75 m. All the recommended agronomic practices, including irrigation, weeding, fertilizer application and plant protection measures, were followed to raise a healthy crop (Anon., 2022) [2] . In each replication, five plants were randomly selected from each plot for recording observations on growth, yield and quality traits, namely vine length, number of primary branches, days to first female flower appearance, node number at which first female flower appears, sex ratio, days to first fruit harvest, fruit length, average fruit weight, number of fruits per vine, fruit yield per vine, total soluble solids and moisture content. The experimental data were subjected to analysis of variance following the procedure suggested by Singh and Chaudhary (1977) [11] . Heterosis was estimated over the better parent (heterobeltiosis), commercial check (Rayanna) and standard check (Kashi Nutan) according to the method described by Turner (1953) [12] . The significance of heterotic effects was tested following the procedure described by Wynne et al. (1970) [14] .

Results and Discussion

The results of analysis of variance revealed non-significant effects of replications for all the characters studied, indicating uniformity of the experimental conditions. Highly significant variations among genotypes for most of the traits suggested the presence of substantial genetic variability in the experimental material. Significant mean squares due to parents and hybrids for the majority of the characters reflected considerable variability among the parental lines and differential performance of their crosses. Further, significant parent vs. hybrid effects for several traits indicated the manifestation of heterotic effects resulting from the recombination of diverse parental genomes (Table 1). The mean performance of the parents, hybrids and checks for the characters studied is presented in Table 2. Such variability among the experimental material provided scope for the identification of superior heterotic combinations. Similar findings were also reported by Nimitha et al. (2018) [9] . Vigorous growth and earliness are important objectives in cucumber breeding, particularly for the development of high-yielding hybrids with early market availability. The estimates of heterobeltiosis, heterosis over the commercial check and standard check for growth traits are presented in Tables 3, 4 and 5, respectively. Significant positive heterobeltiosis for vine length at 90 DAS was expressed by 11 hybrids, with P₁ x P₃ (Swarna Sheetal x Poinsette) recording the highest significant heterobeltiosis (23.49%). For number of primary branches at 90 DAS, 10 hybrids showed significant positive heterobeltiosis, with P₁ x P₃ (Swarna Sheetal x Poinsette) recording the highest significant value (16.15%). Significant positive heterosis over the commercial check was observed in 14 hybrids for vine length and 13 hybrids for primary branches, while 18 hybrids showed significant positive heterosis over the standard check. P₁ x P₃ (Swarna Sheetal x Poinsette) recorded the highest significant heterosis over the commercial check for vine length (31.44%) and primary branches (25.83%), as well as over the standard check (40.88 and 32.45%, respectively). The superior performance of hybrids for both growth traits indicates a favourable parental combination for enhancing vegetative vigour and branching in cucumber. Similar findings were also reported by Umeh et al. (2021) [13] and Chinatu et al. (2024) [4] . Significant negative heterosis for days to first female flower appearance was expressed by 21, 19 and 12 hybrids over the better parent, commercial check and standard check, respectively. The hybrid P₃ x P₇ (Poinsette x Arka Veera) recorded the highest significant negative heterosis over the better parent (-31.24%), commercial check (-30.18%) and standard check (-24.88%). Similar findings were also reported in cucumber by Malav and Verma (2018) [8] . For node number at which first female flower appears, 15 hybrids showed significant negative heterosis over the better parent, while 7 hybrids each exhibited significant negative heterosis over the commercial and standard checks. P₂ x P₃ (Himangi x Poinsette) cross recorded the highest negative heterobeltiosis (-49.06%), whereas P₃ x P₇ (Poinsette x Arka Veera) recorded the highest negative heterosis over the commercial check (-43.48%) and standard check (-38.10%). For sex ratio, significant negative heterosis was observed in 12 hybrids over the better parent and 2 hybrids each over the commercial and standard checks. For days to first fruit harvest, significant negative heterosis was observed in 16, 19 and 5 hybrids over the better parent, commercial check and standard check, respectively. P₃ x P₇ (Poinsette x Arka Veera) exhibited the highest significant negative heterosis over the better parent (-19.41%), commercial check (-23.10%) and standard check (-13.15%). Such desirable negative heterosis for flowering and earliness traits may reflect favourable genetic interactions between the parental lines, particularly in the cross P₃ x P₇, resulting in earlier flowering and fruit harvest. Similar observations of significant negative heterosis for flowering and earliness traits in cucumber were also reported by Sahoo and Singh (2020) [10] in cucumber. Yield and its component traits are important determinants of productivity and market value in cucumber. For number of fruits per vine, significant positive heterosis was observed in 8 hybrids over the better parent, 16 hybrids over the commercial check and 9 hybrids over the standard check. P₁ x P₆ (Swarna Sheetal x Dharwad Local) hybrid showed the maximum heterobeltiosis (21.35%), whereas P₃ x P₇ (Poinsette x Arka Veera) showed the greatest advantage over the commercial (52.94%) and standard (44.44%) checks. For fruit length, 5 hybrids expressed significant positive heterobeltiosis, with P₄ x P₅ (Belagavi Local x Swarna Ageti) showing the maximum heterobeltiosis (15.55%); P₁ x P₃ (Swarna Sheetal x Poinsette) was superior to the commercial and standard checks by 21.24 and 30.05%, respectively. In average fruit weight, significant positive heterosis was expressed by 9 hybrids over the better parent, 5 hybrids over the commercial check and 2 hybrids over the standard check. The maximum heterobeltiosis was observed in P₂ x P₄ (Himangi x Belagavi Local) (12.04%), while P₃ x P₇ (Poinsette x Arka Veera) exceeded the commercial and standard checks by 13.26 and 10.87%, respectively. For the major economic trait, fruit yield per vine, 9 hybrids showed significant positive heterobeltiosis, while 13 hybrids were superior to both the commercial and standard checks. P₁ x P₃ (Swarna Sheetal x Poinsette) expressed the maximum heterobeltiosis (32.37%), whereas P₃ x P₇ (Poinsette x Arka Veera) showed the greatest superiority over the commercial (51.18%) and standard (48.83%) checks. The superior yield of P₃ x P₇ (Poinsette x Arka Veera) may be associated with its favourable performance for number of fruits per vine and average fruit weight, suggesting a complementary contribution of yield components towards enhanced productivity. Similar positive heterotic responses for yield and its component traits in cucumber have been reported by Abd Rabou (2020) [1] , Chinatu et al. (2024) [4] and Dhall et al. (2025) [6] . For total soluble solids (TSS), significant positive heterosis was observed in several hybrids, with P₃ x P₈ (Poinsette x Nethra) showing the maximum significant heterobeltiosis (20.54%), while P₁ x P₅ (Swarna Sheetal x Swarna Ageti) exhibited the highest significant heterosis over both the commercial and standard checks. For moisture content, P₃ x P₄ (Poinsette x Belagavi Local) expressed the highest heterobeltiosis (1.25%), whereas P₇ x P₈ (Arka Veera x Nethra) showed the greatest positive heterosis over the commercial (2.85%) and standard (3.61%) checks. The desirable heterotic response for TSS and moisture content suggests the possibility of improving fruit quality through exploitation of heterosis. Similar findings for heterosis for quality traits in cucumber were also reported by Umeh et al. (2021) [13] and Bisht et al. (2023) [3] . * -Significant at 5% level of probability , ** -Significant at 1% level of probability, VL-90DAS-Vine length at 90 days after sowing, NPB-90DAS-Number of primary branches at 90 days after sowing, DFFA-Days to first female appearance, NFFA-Node at which first female appears, DFHA-Days to first fruit harvest, NFPV-Number of fruits per vine, FL-Fruit length, AFW-Average fruit weight, FYPV-Fruit yield per vine, TSS-Total soluble solids and MC-Moisture content

Conclusion

The study identified P₃ x P₇ (Poinsette x Arka Veera) as the most promising hybrid, combining desirable earliness with superior yield performance, particularly for number of fruits per vine, average fruit weight and fruit yield per vine. The hybrid P₁ x P₃ (Swarna Sheetal x Poinsette) also exhibited superior performance for growth traits, fruit length and fruit yield, while P₁ x P₅ (Swarna Sheetal x Swarna Ageti) and P₇ x P₈ (Arka Veera x Nethra) were promising for TSS and moisture content, respectively. The superior performance of these hybrids may be attributed to favourable genetic interactions between the parental lines, resulting in desirable heterosis for important economic traits. Hence, P₃ x P₇ (Poinsette x Arka Veera) may be further evaluated under multi-location trials and considered for commercial exploitation in cucumber hybrid breeding programmes.

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