Cardinal temperatures for germination in Wild orach (Atriplex dimorphostegia), Saltwort (Salola crassa) and Seepweed (Suaeda aegyptiaca) and effect of temperature on their germination characteristics

Different cardinal temperatures for germination has caused asynchronous appearance of weeds in fieldand so different appropriate management practices to control them, to avoid their invasion. So, in order to study the cardinal temperatures of germination in Atriplex dimorphostegia, Salsola crassa and Suaeda aegyptiaca seeds and effect of different temperatures on their germination characteristics, an experiment was carried out at research laboratory of Faculty of Agriculture in University of Birjand in 2013. The study was conducted based on completely randomized design with 8 levels of temperature (5, 10, 15, 20, 25, 30, 35, and 40○C) and 4 replications. The results of quadratic and dental models showed that cardinal temperatures of germination including base, optimum and maximum temperatures for Atriplex dimorphostegia were 5.57, 26.37, 47.07○C, for Salsola crassa were 3.48, 21.57 and 39.66○C and for Suaeda aegyptiaca were 6.96, 28.81 and 44.52 ○Crespectively. Effect of temperature on all indices of germination in all three weeds were significant (P<0.01) Reduction of percentage and rate of germination at the least temperature compare to the most temperatures in which germination was occurred, were 39.40% and 33.99 %, in Atriplex dimorphostegia and 86& and 66.29% in Salsola crassa and 87.04%, and 94.31% in Suaeda aegyptiaca respectively. The most germination uniformity was occurred at 20○C, 15-20 ○C and 20-40○Cin Atriplex dimorphostegia, Salsula crassaand Suaeda aegyptiaca respectively. Difference between minimum and maximum of Seedling shoot and root length, and Seedling fresh and dry weight were 94.52, 91, 85 and 98.57 percent in Atriplex dimorphostegia, 63.09, 70.12, 71.52, 53.85percent in Salsola crassa and 86.33, 93.99, 96.67 and 99.33 percent in Suaeda eagyptiaca r. The highest seedling vigor index was occurred at 20 ○C in Atriplex dimorphostegia and Salsola crassa and at 10 ○C  in Suaeda aegyptiaca.