TAHA SARHAN1, OMAR KHALEDA ABDULLAH2
1University of Duhok, College of Agriculture, Horticulture, Iraq
2University of Mosul, College of Agriculture and Forestry, Iraq
The present study was carried out at the research field of the Agriculture Research station, Zakho, Duhok Governorate during 2005 and 2006 growing season. A factorial randomised complete block design was selected for the experiment which contained 24 treatments with three replicates to test the effect of Azotobacter inoculation, dry bread yeast suspension and different levels of urea on the growth of potato (Solanum tuberosum) cv. Desiree. Duncan multiple test at 0.05 level was used to detect differences among means. The experiment counted three factors: un-inoculation and inoculation with Azotobacter, four levels of dry bread yeast suspension (0, 2, 4 and 6gml-1 and utilisation of nitrogen mineral fertilisation (urea) at rates of (0, 25, and 50kgdonum-1; 1 donum equals 2500 m2).
The results showed that the vegetative growth was significantly increased in terms of plant height, areal stem number, leave area, total chlorophyll content of leaves and dry matter percentage as a result of Azotobacter inoculation, bread yeast suspension, and the application of urea as compared to the control during both growing seasons.
The dual interaction between Azotobacter inoculation and bread yeast suspension, Azotobacter with urea, and yeast suspension with urea improved the vegetative growth of potato during both growing seasons.
Inoculating potato plants with Azotobacter in combination either with a suspension of bread yeast at a rate of 6gml-1 or fertilising them with 50kg urea donum-1, appeared to be the most effective treatments in improving the vegetative growth traits of potato.
Keywords: Azotobacter, bread yeast, potato