Physiological Response Of Trifoliate Orange (Poncirus Trifoliata L.) Under Drought

Abscises acid (ABA) is a sort of hormone discovered and identified in 1960s, which plays great role in the development of plant and also makes substantial contribution to drought, chilling and salt tolerance. As well, ABA has been regarded as a drought transduction signal. To date, lots of researches have been conducted home and abroad, mainly on biosynthesis, transportation pathway, transduction pathway and regulating inducible gene expression under stress. Although great achievements have been gained, the report about ABA' role in Pontius Trifoliate (drought-tolerant) is rare.One part of the experiment was to treat the PT seedlings under drought for 6h then rewater for 6h, later measured their morphological and stomatic as well as physiological and biochemical changes. In order to uncover exogenous ABA's effect on Pontius Trifoliate (PT) and to provide basic understandings on ABA's role in drought tolerance, PT seedlings are treated in 100uM ABA solution for 5 days then transferred to a 25°C biochemical chamber for 6 hours.Here are the main results:1. Under drought stress, PT's leaves showed the sign of wilting, especially the young ones; after 6h's stress, the stomata closed a bit, but fully closed after relater; the content of chlorophyll plummeted, while increased gradually after relater.2. Under drought stress, the membrane permeability of the leaves from PT increased, the activity of two protective enzymes (SOD, POD) strengthened or maintained in a stable state, content of MDA boosted, Pro and soluble carbohydrate accumulated more.3. Exogenous ABA secured the stability of Pro and soluble carbohydrate in PT, prevented the decline of the activity of SOD, POD or maintained their activity; regulated the metabolism efficiently and suppressed the growth of MDA; thus, eased the stress and enhanced the tolerance of plants.4. Exogenous ABA enhanced the drought tolerance by stabilizing Pro and soluble carbohydrate, slowing the degeneration of SOD and POD, balancing metabolism, suppressing the accumulation of MDA.