Date of Award

12-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Agricultural Education

First Advisor

Dr. Abdul laleel Cheruth

Second Advisor

Dr. Mhammad Salem AI-Yafei

Third Advisor

Dr. Shyam S. Kurup

Abstract

Economically important vegetable crop lettuce (Lactuca sativa L.) of family Asteraceae was selected for the present investigation. It is being cultivated in UAE due to its commercial importance. In lettuce cultivation, major problem is the requirement of large quantity of irrigation water. The present study was aimed to reduce the water consumption of lettuce cultivation, for that, a varied irrigation regime was used with the application of abscisic acid (ABA). The parameters studied were growth, photosynthetic pigments, biochemical constituents, antioxidant potential and antioxidant enzymes activities in lettuce plants under drought stress and its response to ABA under stress. Drought stress decreased the morphological parameters like root, shoot length, total leaf number, fresh and dry weight in lettuce. The growth parameters increased in ABA treatments under drought stress. The pigment contents of the lettuce leaves also showed the same trend. But drought stress caused an increase in the biochemical constituents like proline and amino acid contents when compared with control. All these parameters also increased under individual ABA treatments and treatments under drought stress. ABA treatments to the unstressed plants caused an increase in these parameters. The non-enzymatic antioxidant molecules like ascorbate and ἁ-tocopherol showed significant increase under drought condition in lettuce. ABA slightly reduced these contents. The antioxidant enzymes like superoxide dismutase, catalase and peroxidase showed significant increase under drought condition and ABA caused significant enhancement in these antioxidant enzymes under drought stress and also in unstressed conditions, thereby protecting the plants from the deleterious effects of drought stress. From the results of this investigation, it can be concluded that ABA at 10 µg/l can be used as a potential tool to minimize the drought stress effects in lettuce cultivation.

Included in

Apiculture Commons

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