Histological Responses of Two Wheat Species to Azospirillum Inoculation under Dryland Farming

In this experiment the effect of inoculation with Azospirillum on the flag leaf and spike rachis anatomical features and also on grain yield and grain weight was investigated for the first time in bread and durum wheats during 2015-2016 growing season under semi-arid condition. The crop yield increased due to the inoculation with Azospirillum with a maximum yield increase of about 8.0 per cent for bread wheat. Azospirillum led to an increase in grain weight per spike. Yield increase due to Azospirillum inoculation was higher for bread wheat than durum wheat. The two wheat species exhibited differences in flag leaf and spike axis anatomic features. Although Azospirillum inoculation decreased the number of flag leaf stomata by 11.5% irrespective of the wheat type, stomatal length of the inoculated plants increased by about 3.6 and 11.5% for bread wheat and durum wheat, respectively. Azospirillum inoculation significantly enhanced the area and length of xylem and phloem vessels by about 12.5 and 12.39% and 14.42 and 33.33%, respectively. Area of the bundle sheath and mesophyll layers of inoculated plants was increased by 20 and 31.5%, respectively. Azospirillum inoculation enhanced the area of upper and lower epidermis of the bread wheat much more than the durum wheat. Anatomic changes due to Azospirillum was not limited to the flag leaf but also extended to the spike rachis and, therefore the inoculated plants had higher area of vascular bundle, xylem vessel and phloem vessel. Overall,the effect of Azospirillum on anatomical features and grain yield of wheat was slightly species specific and it was more pronounced in the bread wheat as compared to the durum wheat.