NEW AZOTOBACTER TRANSFORMANTS TO IMPROVE GROWTH OF SQUASH PLANTS UNDER SALINITY STREESS.

Abstract

This study was carried out at the laboratory of genetic department and the farm of horticulture department Fac. of Agri. Minia University in two successive seasons on f 2003 and 2004. In this study some transformants of Azotobacter showed high tolerance against saline water (0.25, 0.50, 0.75, 1.oo, 1.25, 1.50, 1.75, and 2.00 g/ 100 ml w/v). Azotobacter transformants were obtained by incubating wild isolate of Azotobacter with an isolate of Bacillus spp., tolerant to 30% NaCl, for 2 or 24 hrs.These resulted transformants were tested in pot experiments under four levels of salinity and presence of squash plants as indicator. The results revealed that: 1- The wild type strain of Azotobacter was sensitive to 1.5-2.0% NaCl as recipient comparison to the Bacillus spp .which resistant to 30%NaCl as donor. 2- The transformants of Azotobacter were obtained after two hours incubation were less in their frequencies than those were obtained after 24 hours incubation with DNA of Bacillus sp. 3- Adding transformants of Azotobacter to salinity soil led to reduction in the symptoms of salinity on squash plants. 4- Different transformants varied in their effects, regards, plant growth characters under salinity conditions and T2 & T4 showed the best effect.