Genotypic variation in auxin-induced rooting response of detached tomato leaves: an innovative approach for indirect evaluation of yielding ability in tomato (Solanum lycopersicum L.)

In this study, the extent of genetic variation in auxin-induced rooting response of detached tomato leaves has been assessed and correlated with yielding ability. Fully expanded, healthy and disease-free compound leaves were excised and treated with 500 ppm aqueous indole butyric acid solution for 45 sec, then washed thoroughly with tap water and kept in beakers filled with distilled water. The leaves were examined randomly for the number of roots induced, length of the longest root, fresh root weight and frequency of rooted leaves to determine variation in auxin response of the genotypes. Auxin-treated detached leaves of 22 tomato genotypes showed wide variation in their root traits. The genotypic coefficient of variation for the number of roots, root length, fresh root weight and frequency of rooted leaf cuttings was 45.43, 11.72, 38.45 and 31.66 respectively. Auxin sensitivity index (ASI) of the genotypes ranged from 0.0 to 3.0. A significant positive correlation (0.647) was observed between ASI and fruit yield. This study reveals that genetic variation in the auxin-induced rooting response of detached tomato leaves could be used as an indicator for screening high-yielding tomato genotypes. This innovative approach is simple, rapid and inexpensive.