Abstract
A study was conducted at the nursery and silviclture laboratory in forestry Department for the period from the 1st of February until the end of November 2007 . This study aimed to achieve chromosomal polyploidy in Robinia pseudoacacia L. by soacking their seeds in different Colchicine solution concentrations and different periods.The treated seeds were sown in plastic bag polly ethelen containing sandy loam soil bag were placed in shaded woody shelter .other seed lots treated with colchicine were placed in incubator after sowing them in petri – dishes to count seed germination percentages followed by chromosome counts in root apicses as following :
Colchicine concentration effect : The experiment shows chromosomal tetraploidy 48 chromosome = 4n when seeds soacked in colchicine solution with concentration 1000 mlg / l . the value recorded was 34.68 % at a same time that the mean of this ratio when soacking seed in solution colchicine 500 mlg / l was 5.55 % . also soacking seeds in a solution of 2000 mlg / l induced a triploid plants 36 chromosome = 3n with ratio of 32.79 % . But other remaining treatments chromosome number had their original diploid number 24 chromosome = 2n . In characteristics studied concentration of colchicine 2000 mlg / l caused a reduction in seeds germination percentage 28.20 % in comparison with control 0.00 mlg / l . also 1000 mlg / l solution of colchicine reduced the mean value for traits : leaf shape factor and stomata number / mm2 as follows 18.81 . 55.31 % respectively . while this concentration 1000 mlg / l resulted in increasing the mean values of shoot length 30.43 % .shoot diameter 38.26 % . stomata length 49.63 % and stomata width 56.30 % when compared with values of control treatment 0.00 mlg / l colchicine .
Soacking periods effects :Period of 24 hr. soacking in solution gave significant effect in most traits studied while a reduction of means was recorded for germination ratio .
leaflet shape ratio and stomata number .
Interaction effect of colchicine concentration & soacking Periods :
Soacking seeds in colchicine solution 2000 mlg / l for period of 24 hr. resulted in a reduction of the means of seeds germination ratio 31.23 % . when soacking those seeds in 1000 mlg / l colchicine for 24 hr. increcases the values of shoot length . shoot diameter . stomata length and stomata width traits. this significant increases was 31.31 . 35.17 . 43.57 and 54.90 % respectively also this interactions causes reduction in values of leaf let factor ratio 31.25 % . and stomata numbers / mm2 53.84 % in comparison with control treatment 0.00 mlg / l colchicine .
