MSc

Brinjal, known as eggplant or guinea squash (Solanum melongena L.), belongs to the Solanaceae family. The fruit from the genus Solanum is also called “The King of vegetables”. It is an important solanaceous crop cultivated worldwide and is native to the Hindustan-China center, where it still grows in the wild. The brinjal crop is highly vulnerable to several pests and diseases. Among these, the production and productivity of the crop are severely affected by brinjal shoot and fruit borer (BSFB; Leucinodes orbonalis G.) reducing its market value. The loss caused by the pest may reach up to 70 - 92 per cent. The inadequacy of reliable biological control for the management of BSFB leaves farmers to resort to insecticides. This underscores the critical necessity for extensive research and the development of varieties resistant to shoot and fruit borer. Such resistant varieties have the potential to emerge as the most environment friendly, cost-effective, and sustainable method for pest control. In this context, the present study entitled “Screening early segregating generations of brinjal (Solanum melongena L.) for resistance against shoot and fruit borer” was conducted to investigate and select the superior lines with resistance to shoot and fruit borer from early segregating generations. Segregating generations of two crosses i.e., Ponni × Vengeri (F3 and F4 generations) and Ponni × IC624241 (F2 generation) were evaluated along with the parents and check varieties.
Segregation with wide variation was observed in all the generations viz—F2, F3, and F4 of the respective crosses. Regarding fruit colour, both the segregating generations of Ponni (green) × Vengeri (purple-green) showed wide variation in the colouring pattern. The segregating generations had both oblong and long-shaped fruits similar to parental types i.e., Ponni (oblong) and Vengeri (long). Besides, elongated fruits were also observed in both generations. All the fruits in the F2 generation of Ponni × IC624241, exhibited green colour similar to the parent Ponni whereas, the fruit shape was round as in IC624241.
Range, mean, variance, genotypic coefficient of variance (GCV) (%), phenotypic coefficient of variance (PCV) (%), heritability (H2), genetic advance (GA), genetic advance as percentage over mean (%) (GAM), skewness, kurtosis, and correlation between growth and yield traits were estimated in F2, F3, and F4 generations of the respective crosses. PCV was higher than GCV for all the traits in all the generations. The observed variability across all studied populations remained consistently high for various traits. This variability persisted in the subsequent generations, as indicated by the range, GCV, PCV, H2, GA, GAM, skewness, and kurtosis. This suggests that a single seed descent (SSD) method was employed throughout the generations without any selection process.
For pedigree selection BSFB scoring according to Mishra et al., (1988) at the fruiting and shooting stage was performed and all the lines were categorized as susceptible to highly susceptible in accordance with their scale. The selection criteria for identifying the best-performing lines were based on percentage of fruit infestation, marketable yield, fruit yield per plant, and percentage of shoot infestation. Based on the selection criteria lines 1.2.18, 1.2.10, and 1.3.10 were identified from the F3 generation of the cross between Ponni × Vengeri and were forwarded as F4 lines. In the F2 generation of the cross between Ponni × IC624241, five F2 plants showed 50 per cent of fruit resistance but, due to susceptibility to bacterial wilt and low population size, further studies were not conducted.
Correlation data from F3 (Ponni × Vengeri) and F2 (Ponni × IC624241) generation of the crosses revealed a positive association between the number of flowers, number of shoots, fruits per plant, and length of fruit with shoot and fruit infestation. However, in the F4 generation of Ponni × Vengeri the length and diameter of the fruit showed a negative correlation with the shoot and fruit infestation by BSFB. Fruit yield per plant was positively associated with the number of flowers, shoots, fruits, length of fruit, and average fruit weight in all the studied populations. The diameter of the fruit also showed a positive association with yield in the F2 (Ponni × IC624241) and F4 (Ponni × Vengeri) populations of the crosses.
Superior lines selected through the pedigree method in terms of marketable yield and resistance to BSFB were identified from the F3 forwarded F4 generation of Ponni × Vengeri, the lines were 1.2.18.8, 1.2.10.7, and 1.3.10.7 (in descending order of their performance). The superior lines with resistance for fruit infestation from F4 generation developed through SSD were 1.3.11.2 (0 %), 1.4.13.2 (50 %), and 1.10.16.4 (0 %). The identified lines from the F4 generation of cross Ponni × Vengeri may be forwarded further to develop resistant varieties and other studies.