Evaluation of tomato (Solanum lycopersicum L.) hybrids under walk-in net tunnel: morphological characterization and correlation analysis

Introduction

Tomato (Solanum lycopersicum L.; 2n = 2x = 24) is an important vegetable crop with high dietary, processing and economic value. The crop is sensitive to environmental conditions during flowering and fruit set, making protected cultivation relevant where temperature, rainfall and pest pressure constrain open-field production. Walk-in net tunnels provide a comparatively low-cost protected environment that can modify the crop microclimate and reduce insect pressure. The performance of a hybrid, however, remains dependent on its genotype × environment interaction; consequently, characterization of available hybrids under the target production environment is useful for varietal identity, seed purity and subsequent evaluation. The PPV&FRA DUS framework provides standardized descriptors for establishing varietal distinctness, uniformity and stability. Morphological characterization is particularly useful because qualitative traits such as stem pigmentation, leaf serration, fruit green shoulder, fruit shape and stigma configuration can act as diagnostic markers. Reddy et al. (2017) [1] demonstrated that combinations of morphological characters could distinguish tomato hybrids and their parental lines, with several markers remaining stable over two seasons. More recent tomato characterization studies likewise emphasize the value of qualitative descriptors for varietal identification and DUS testing (Sushma et [3,4,5,2] . Limited information is available on the performance and adaptability of tomato hybrids under walk-in net tunnel conditions in Chhattisgarh. Most studies have focused on open-field or other protected conditions. Therefore, there is a need to evaluate different hybrids for growth, yield and quality, characterize them using DUS traits, and identify suitable high-yielding hybrids for commercial cultivation under walk-in net tunnels.

Materials and Methods

Experimental site and plant material

The experiment was conducted at the Centre of Excellence on Protected Cultivation and Precision Farming Unit, in walk-in net tunnel, Department of Vegetable Science, College of Agriculture, IGKV, Raipur, Chhattisgarh, during rabi 2025-26. Thirteen tomato hybrids were evaluated: Kashi Abhiman, Arka Rakshak, Arka Vishesh, Arka Apeksha, Arka Abhed, Arka Samrat, Arka Aditya, Abhilash, Uma, Pari, Saaho, Baaho and NS-962. The experiment was laid out in Randomized block design with three replications, a plot size of 4.80 m 2 and spacing of 120×60×60 cm. Seedlings were transplanted on 30 October 2025. All the cultural practices and application of nutrients were applied as per recommendation through drip system.

Morphological characterization

Characterization was undertaken with descriptor states corresponding to the tomato DUS framework. The characterization table contained 46 descriptor traits like seedling, plant, stem, leaf, inflorescence, flower and fruit characters. Observations were recorded at the appropriate crop stages and the predominant descriptor state was assigned to each hybrid. Quantitative observations used in the correlation analysis were based on ten tagged plants per plot for growth traits and standardized observations for flowering, fruiting and yield traits.

Correlation analysis

The correlation matrix supplied separately for this paper was used without alteration. Pearson product-moment correlation coefficients (r) were examined between measured growth/flowering/fruiting traits and fruit yield per hectare. The significance notation already present in the supplied matrix was retained (* and **). The pattern of significance is consistent with analysis based on 39 observations (13 hybrids × 3 replications); therefore, the coefficients are interpreted as statistical associations and not as evidence of causation. Correlation analysis in tomato has previously been used to identify yield-associated characters such as fruit weight, fruits per plant, branches and flowers per cluster (Reddy et al., 2019) [6]

Results and Discussion

DUS characterization of tomato hybrids

The 46 descriptor traits were recorded to differentiate the hybrids across several descriptor states, although a number of traits were monomorphic in the material. All thirteen hybrids were indeterminate and possessed stem pubescence, while flower colour was uniformly yellow, anther colour yellow, stigma non-exserted, style pubescence present, and mature fruit colour red. Conversely, polymorphism was evident for seedling hypocotyl anthocyanin coloration, leaf green in-tensity, stem anthocyanin strength, internode length, leaf and leaflet dimensions, leaflet serration, leaf structure and attitude, inflorescence type, stigma lobing, calyx size, peduncle abscission layer, fruit green intensity, green shoulder, fruit size, fruit shape, ribbing, peduncle-end depression, blossom scar, blossom-end shape, locule number, firmness, maturity time and TSS. Such combinations are useful as morphological fingerprints rather than as indicators of agronomic superiority. Arka Abhed was the only hybrid recorded without anthocyanin coloration of the hypocotyl, whereas the remaining twelve showed presence. Leaf green intensity separated Arka Samrat, Uma and Saaho as medium from the ten dark-green hybrids. Stem anthocyanin coloration separated weak and medium classes, with Arka Vishesh, Arka Samrat, Arka Aditya, Uma, Pari, Saaho and NS-962 in the weak class and Kashi Abhiman, Arka Rakshak, Arka Apeksha, Arka Abhed, Abhilash and Baaho in the medium class. Leaflet serration also differentiated less-serrated and highly serrated groups. These patterns agree with the broader usefulness of stem pigmentation, leaf serration, stem pubescence, fruit shoulder and fruit-shape characters reported for tomato identification (Reddy et al., 2017) [1] . Fruit descriptors provided especially visible differentiation. Four hybrids (Kashi Abhiman, Arka Rakshak, Arka Vishesh and Arka Apeksha) lacked a green shoulder before maturity, whereas the other nine showed it. Fruit longitudinal shape ranged from ovoid and heartshaped to obovoid, circular, slightly flattened and flattened. Arka Rakshak was heart-shaped, Arka Vishesh and Arka Apeksha were obovoid, and Kashi Abhiman was ovoid. The descriptor table also separated stigma lobing, blossom-end shape and ribbing, demonstrating that a combination of traits is more informative than any single descriptor. This is consistent with published tomato DUS work in which combinations of morphological markers were effective in differentiating closely related materials (Reddy et al., 2017; Uppuluri et al., 2023) [1,4] . fruit set, FS%80 DAT-Fruit set % at 80 DAT, FS%95 DAT-Fruit set % at 95 DAT, NFPC 80 DAT-Number of fruits per cluster at 80 DAT, NFPC 95 DAT-Number of fruits per cluster at 95 DAT, NFP-Number of fruits per plant, CL-Calyx length (cm), FL-Flower length (cm), TFBB-Thickness of flower bunch base (mm), LFB-Length of flower bunch (cm), TY-Total yield (t/ha) TNFP-Total number of fruits per plant, Wt. 10 fruits-Weight of 10 fruits (g), FW/P-Fruit weight per plant (kg), FL-Fruit length (cm), FW-Fruit width (cm), FV-Fruit volume (cm 3 ), PT-Pericarp thickness (mm), NOL-Number of locules, SCCS-Size of core in cross section (cm), DFP-Days to 1 st picking, NSPF-Number of seeds per fruit, TW-Test weight (g), MY-Marketable yield (q/ha), UMY-Unmarketable yield (q/ha), TY-Total yield (t/ha)

Conclusion

The thirteen tomato hybrids displayed clear variation for a substantial set of PPV&FRA-aligned morphological descriptors under walk-in net tunnel conditions, particularly for stem anthocyanin pigmentation, leaf structure and serration, inflorescence type, stigma lobing, fruit green shoulder, fruit size and shape, blossom-end characters, locule number, firmness and TSS classes. Several descriptors were monomorphic across the material, and these common states should be considered together with the polymorphic characters when documenting varietal identity. The correlation analysis showed strong positive associations of fruit yield with fruits per plant, fruit-set percentage at 80 DAT, fruits per cluster and selected early vegetative traits. These findings support the use of standardized morphological characterization alongside quantitative association analysis for documenting released tomato hybrids, but they should not be interpreted as proof of causation or as a substitute for formal DUS testing or multi-environment validation.

Acknowledgement

AcknowledgementsThe authors acknowledge the Department of Vegetable Science and Centre of Excellence on Protected Cultivation and Precision Farming unit, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh, India for providing the necessary facilities for this study.

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