Water relations of wheat influenced by exogenous application of growth substances under moisture stress. Hafiz Muhammad Akram*, Abdus Sattar, Hafiz Saeed-ur-Rehman and Abbas Ali

Water potential is amongst the most useful parameters for the measurement of the degree of water stress in plants. With the objective of mitigating adverse effects of moisture stress on water potential, osmotic potential and pressure potential of wheat variety Inquilab-91, a greenhouse experiment was conducted using two moisture levels viz., normal moisture supply and moisture stress at crown root stage. The moisture levels were randomized in main plots and growth substances including distilled water, Ethephon @ 400 mg l-1, Paclobutrazol @300 mg l-1, SADH @ 2000 mg l-1 and Triadimefon @ 200 mg l-1 were kept in sub-plots. Whereas, stages of growth substances application, i.e., pre-sowing seed treatment and foliar spray at crown root development, heading and grain filling were randomized in sub-plots. Water stress at crown root development stage was imposed simply by withholding irrigation. Moisture stress significantly lowered water potential and pressure potential and enhanced osmotic potential while growth substances application ameliorated all the traits under study; however, stages of application showed a varied response in this regard. Ethephon application @ 400 mg l-1 had pronounced effect with higher water potential (-1.584 MPa), osmotic potential (-1.781 MPa) and turgor potential (0.217 MPa) values. Amongst the stages of growth substances application, pre-sowing seed soaking in different growth substances was found to be the most effective in maintaining plant water balance. Interaction of moisture levels, growth substances treatments and stages of their application was highly significant. Thus, Ethephon application @ 400 mg l-1 as pre-sowing seed treatment under moisture stress conditions depicted the highest values of water potential (-2.080 MPa), osmotic potential (-2.268 MPa) and turgor potential (0.186 MPa).