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Tamil Nadu Agricultural University (2013)

Studies on physiological biochemical and molecular basis of drought tolerance in tomato lycopersicon esculentum mill

Sivakumar R.

Titre : Studies on physiological biochemical and molecular basis of drought tolerance in tomato lycopersicon esculentum mill

Auteur : Sivakumar R.

Université de soutenance : Tamil Nadu Agricultural University

Grade : Doctor of Philosophy (PhD) in Crop Physiology 2013

Résumé
The investigation was aimed at to screen the tomato genotypes for drought tolerance and to elucidate informations on morphological, physiological and biochemical mechanisms of drought tolerance. A study was also carried out to assess the effect of PGR’s on alleviating the drought stress effects in tomato genotypes. To achieve these objectives, a series of experiments in laboratory, pot culture and field conditions were carried out with tomato genotypes. In the laboratory experiment, screening of thirty two genotypes were made at two critical PEG concentrations of -0.2 MPa and -0.35 MPa. The results of the investigation revealed that at higher concentration of the PEG, the germination percentage, seedling growth and vigour index decreased drastically. All the thirty two genotypes displayed their differential responses to two levels of PEG concentrations. Among the genotypes, LE 118, LE 57, LE 27, LE 14, LE 18 and LE 13 showed high degree of tolerance with high germination percentage, low reduction in vigour index and high stress tolerance index. Therefore, these genotypes were grouped as tolerance to imposed water deficit stress. The genotypes LE 1, LE 5, LE 3, LE 20, LE 85, LE 100 and PKM 1were considered as susceptible, they were unable to germinate at higher level of PEG. The remaining genotypes showed a moderate performance, out of which LE 23, LE 114, LE 125, CO 3, TNAU THCO 3 and COTH 2 were selected for further evaluation along with the tolerant and susceptible genotypes under pot culture conditions.In the pot culture experiment, the selected eighteen genotypes viz, LE 1, LE 3, LE 5, LE 13, LE 14, LE 18, LE 20, LE 23, LE 27, LE 57, LE 100, LE 114, LE 118, LE 125, CO 3, PKM 1, TNAU THCO 3 and COTH 2 were subjected to two irrigation levels (100% FC and 50% FC). The results revealed that irrigation at 50% FC showed greater inhibitory effect on overall growth of all the genotypes. However, LE 27, LE 57, LE 114 and LE 118 were grouped as the tolerant genotypes and LE 1, LE 3, LE 5 and LE 125 were sensitive lines based on their yield performance under 50 per cent FC. Maintenance of optimum leaf area with high SPAD value, soluble protein and proline contents along with high TDMP and expression of antioxidant enzymes like catalase and superoxide dismutase were observed to be the physiological basis for tolerance to drought.

Présentation et version intégrale (Shodhganga)

Page publiée le 18 avril 2021