Genetic evolution of morphological, physiological and biochemical traits tomato (Lycopersicon esculentum Mill.)

Abstract

Seven high yielding cultivars from each growth habit, viz., indeterminate (ID), semideterminate (SD) and determinate(D), randomly representing releases from USA and India since 1952 to date, were grown along with two accessions of Lycopersicon cerasiforme, and one accession of L.pimpinellifolium. The cultivated varieties were superior to the related wild species for yield, average fruit weight, locule number, and fruits per plant. All major yield components were observed to be independent of growth habit. Physiological parameters were monitored at 4 stages of crop growth. The differences between the growth habits were distinct 60 days after sowing. Leaf size was observed to be smaller in the wild types. Both leaf dry weight and leaf area (5th leaf) were correlated with fruit size, indicating that increased leaf size may have evolved with large fruits. Stem dry weight was highest in wild genotypes followed by ID, SD and cultivars. Harvest index (HI) was observed to be 65 to 70% in the determinate cultivars. SD had HI of 55% followed by ID with around 50% and wild types with 48%. The recent varieties thus are more efficient in mobilizing available resources towards economic yield. Total biomass was highest in the wild types followed by ID, SD and types. The wild genotypes were superior in TSS., ascorbic acid, acidity and also sugar: acid ratio. A progressive decline in these traits was observed from ID to D cultivars indicating that yield increase may have been at the expense of quality. Lycopene content was observed to be independent of growth habit.