Tomatoes are commonly grown in India under supportless ground culture. Growers prefer around 7 harvests to even out price fluctuations and because the smaller loads of each harvest are more easily transported. Looking for the most productive ideotype to suit such conditions, data were recorded on 16 vegetative and reproductive traits on 226 lines of tomato grouped into indeterminates (83 lines), semi-determinates (42 lines) and determinates (101 lines) following the classification of Lapushner et al. (1976).
A comparison of means, variances and frequency distribution on the basis of 't', 'F' and chi-square tests of contingency showed the 3 groups to be dissimilar. The frequency distribution of 9 characters was observed to be dependent on the 3 growth habit classes. Indeterminates differed from the other 2 groups for 9 traits including yield per plant, plant height, and soluble solids. This group showed higher variability for most characters. Semi-determinates were observed to have higher mean values over determinates for 4 of the traits (yield per plant, plant height, fruit set and flesh thickness).
Further, the character associations and their pathways to yield, were not similar in the 3 groups suggesting differences in source and sink strengths and their interrelationships. This would imply the gene action for growth habit to be more complex than previously thought.
Since the yields of semi-determinates, spread over 5-6 harvests, were on par with indeterminates and higher than determinates they appear to be the ideal growth habit for handpick harvests, their reduced plant height making them agronomically more suited for supportless ground culture. Efforts are now directed to transfer desirable processing as well as fresh market characteristics into a semi-determinate background.
Literature cited:
Lapushner, D., R. Frankel, R. Guttman and L. Guttman. 1973. Genetic variation in a large population of tomato varieties. 1. Analysis of distribution of single traits. Euphytica 22:484-494.