GROWTH RESPONSES OF Parthenium hysterophorus L. GROWING UNDER SALT STRESS

The present study conducted during 2009-10 prescribed the potential of varyingly devised osmotic constrains on germination and growth as well as mycorrhizal association of Parthenium hysterophorus, an alien and highly invasive weed species. The effects of differential salinity concentrations of three selected salts viz. NaCl, KCl, and MgSO4 were evaluated on germination and growth of P. hysterophorus in lab as well as field trials at Institute of Agricultural Sciences, University of the Punjab, Lahore. The different concentrations of test salts for lab experiments were 10, 20, 30, 40 mM, and for field experiments were 500, 750, 1000, 1250 mM. The control treatment with simple water irrigation was marked as 0 (zero). The parthenium plants were allowed to grow in silty loam textured soils in pots. Twenty five days old seedlings were allowed to establish in the pots. Saline sprays with test salts were carried out one week after transplantation. In the results, different salts had different mechanisms of affecting the plants. Average decline of 86% was observed in germination of parthenium against maximum concentrations. In both of the lab and field experiments, shoot and root fresh weights were severely affected in comparison to the dry weights. Mycorrhizal colonization was higher in the control treatments against all the saline conditions. Significant decline in chlorophyll content was evidenced in case of KCl. The salinity threshold of P. hysterophorus was estimated up to 0.75 M, growth was strongly decreased and growth was significantly reduced at higher salinity regimes.