Correlation and path coefficient analysis for cob yield and its component traits in baby corn (Zea mays L.)

Introduction

Maize (Zea mays L.) is one of the most important cereal crops owing to its wide adaptability, high productivity and diverse uses as food, feed, fodder and industrial raw material and cultivated on more than 200 million hectares and contributing nearly 1.24 billion tonnes to global food production in 2023-2024 (FAOSTAT, 2024). The rising demand for vegetables from both human and livestock populations has increased the need for enhanced production of baby corn. Among the diversified forms of maize, baby corn, harvested at an immature stage before fertilization, has emerged as a high-value vegetable crop due to its short duration, multiple pickings and increasing market demand. Under improved agronomic practices, baby corn yields range from 7 to 10 t ha⁻¹, making it suitable for intensive cropping systems and higher farm profitability. Cob yield in baby corn is a complex quantitative trait governed by several interrelated morphological and phenological characters. Correlation analysis provides insight into the magnitude and direction of associations between yield and its component traits, while path coefficient analysis partitions these associations into direct and indirect effects, enabling identification of characters with true causal influence on yield. Therefore, the present study was undertaken to assess phenotypic and genotypic correlations and path coefficients among yield and yield-related traits in baby corn across multiple environments, with the objective of identifying key characters for improving cob yield per plant.

Materials and Methods

The present investigation was undertaken to study phenotypic and genotypic correlations and path coefficients among yield and yield-related traits in baby corn (Zea mays L.) across three environments. The experimental material consisted of 105 genotypes, comprising 75 F₁ hybrids, 28 parents and two checks (DMR-1142 and DMR-1144). The parental lines included CM-104, CM-115, CM-119, CM-201, BML-5016, BML-5118-3, BML-5160, BML-5161, BML-5219, BML-5222, BML-5342, QPM-57-1, BML-5063-1, BML-5204-3, BML-5121, BML-5212, BML-5347-2, QPM-33, QPM-63-1, BML-5204-5-2-1, BML-5207, BML-5204-1-8, QPM-49, QPM-69-2 and QPM-62, while BML-6, BML-13 and CM-131 were used as testers. The parents were crossed in a Line × Tester design to generate 75 hybrids. The experiment was conducted during the kharif season at three locations: College Farm, Rajendranagar; RARS, Jagityal; and ARS, Kampasagar, Telangana. The trials were laid out in a Randomized Block Design with three replications at each location. Each genotype was grown in a single 4 m row with a spacing of 60 × 20 cm. Observations were recorded for all traits following standard procedures. Correlation coefficients were estimated to determine associations among traits, and path coefficient analysis was performed to partition correlations into direct and indirect effects on cob yield per plant. Analyses were carried out for individual environments and pooled over locations.

Table 1: List of the maize inbred lines & crosses used in the study

Parent & Crosses Phenotypic and genotypic correlation coefficients among yield and its component traits were estimated across Rajendranagar, Jagtial, Kampasagar and in pooled analysis. In general, genotypic correlations were higher than phenotypic correlations, indicating strong inherent genetic associations, though their phenotypic expression was reduced due to environmental influence. Days to 50% tasseling showed a strong positive phenotypic correlation with days to 50% silking at all locations (0.9291to -0.9484) and in pooled analysis (0.9317). However, it exhibited significant negative phenotypic correlations with cob yield per plant at Rajendranagar (-0.2062), Jagityal (-0.2419), Kampasagar (-0.1137) and pooled analysis (-0.1927), suggesting the adverse effect of delayed flowering on yield. Days to 50% silking also recorded significant negative correlations with cob yield per plant across locations (-0.1179 to -0.2549) and in pooled analysis (-0.2010). Plant height exhibited significant positive phenotypic correlations with ear height, baby corn length, cob weight, number of cobs per plant and cob yield per plant at all locations, with a strong association with cob yield per plant in pooled analysis (0.6361). Ear height was similarly positively correlated with cob yield per plant across environments (0.5329-0.6765) and in pooled analysis (0.5927). Baby corn length showed a significant positive phenotypic correlation with cob yield per plant at Rajendranagar (0.6525), Jagtial (0.7716), Kampasagar (0.4969) and pooled analysis (0.5954), mainly through its strong association with cob weight. Baby corn girth exhibited mostly non-significant correlations with cob yield per plant across locations. Cob weight showed a highly significant positive phenotypic correlation with cob yield per plant at Rajendranagar (0.6899), Jagityal (0.8420), Kampasagar (0.7405) and pooled analysis (0.7661). Number of cobs per plant recorded the highest positive association with cob yield per plant across all locations (0.6489-0.8996) and in pooled analysis (0.8207), indicating its primary role in yield determination. Overall, cob yield per plant was positively associated with number of cobs per plant, cob weight, baby corn length, plant height and ear height, and negatively associated with days to 50% tasseling and silking. Path coefficient analysis revealed that days to 50% tasseling exerted a negative direct effect on cob yield per plant across locations and in pooled analysis (-0.0428), confirming the detrimental effect of delayed flowering. Although days to 50% silking exhibited a small positive direct effect (0.0510), its overall association with yield was negative due to strong negative indirect effects through tasseling and number of cobs per plant. Plant height and ear height showed low to moderate direct effects on cob yield per plant; however, their positive correlations with yield were mainly due to substantial indirect effects via cob weight and number of cobs per plant. Baby corn length exhibited a consistent positive direct effect on cob yield per plant, particularly in pooled analysis (0.0611), along with strong indirect effects through cob weight. Cob weight exerted a high and consistent positive direct effect on cob yield per plant across locations (0.4658-0.7279) and in pooled analysis (0.5295), establishing it as a major yield determinant. Number of cobs per plant recorded the highest positive direct effect on cob yield per plant at Rajendranagar (0.7817), Jagityal (0.6297) and in pooled analysis (0.6603), while at Kampasagar it ranked second after cob weight (0.6743). The residual effects were low at Rajendranagar (0.1983), Jagityal (0.1016), Kampasagar (0.0836) and in pooled analysis (0.0183), indicating that the traits included adequately explained the variation in cob yield per plant. Correlation and path coefficient analyses indicated that number of cobs per plant and cob weight were the most important traits contributing directly to cob yield per plant, followed by baby corn length. Negative direct effects of flowering traits highlight the importance of earliness. Hence, selection for genotypes with higher number of cobs per plant, heavier cobs, longer baby corn and early flowering would be most effective for improving cob yield in baby corn.

Acknowledgement

AcknowledgementWe wholeheartedly acknowledge the support in terms of fund and guidance given by faculty at College of Agriculture, Rajendranagar, Hyderabad. Regional Agricultural Research Station Jagtial, Karimnagar and Agricultural Research Station, Kampasagar, Nalgonda

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