IN VITRO SELECTION OF SOMACLONES OF SUGARCANE UNDER DROUGHT STRESS CONDITION AND THEIR EVALUATION IN FIELD CONDITION

Abstract

In vitro selection was conducted to select for drought tolerant somaclones in sugarcane variety Isd 28. Unexpanded spindle leaf sheath was used as explants. MS medium supplemented with 2, 4-D (3 mg l-1) and coconut water (10 %), BAP (2 mg l-1) with Kn (1 mg l -1), NAA (5 mg l-1) were used for callus induction, shoot regeneration and root formation respectively. To develop of drought tolerant sugarcane somaclones in vitro medium was stressed with different concentrations of PEG such as 5, 7.5 and 10 % along with control (without PEG). Callus growth was vigorous at control as well as at lower concentration of PEG. The frequency of callus induction decreased with the increase of PEG concentration. Shoot and root production capacity also decreased with the increase of PEG concentration. Most callus became reddish black and died within 40-45 d on the medium supplemented with 10 % PEG. Shoot and root formation observed on medium supplemented with 5 % PEG. Twenty somaclones were studied for drought tolerance. Biochemical parameters such as total chlorophyll, chlorophyll a, chlorophyll b, chlorophyll a:b ratio and CSI showed positive correlation as well as morphological parameters such as leaf number and leaf area showed negative correlation to drought tolerance in somaclones and parents. Tolerance level was measured based on greenness of leaves as well as data recorded on biochemical and morphological parameters. Close association with biochemical and morphological parameters was observed for drought tolerant reaction. Less variation on Brix per cent was observed among somaclones and their parents. Somaclones Isd 28Sc-3, Isd 28Sc-8,Isd 28Sc-11, Isd 28Sc-17 and Isd 28Sc-18 of parent variety Isd 28 were observed as highly tolerant somaclones.