Abstract
Seven week old pigeonpea (Cajanus cajan L.) plants grown in sand culture were detopped (stem excised just above the sand surface) at the 6th, 10th,14th, and 18th h of the day and sampled after every 4 hours up to a total period of 12 hours. Irrespective of the time of detopping, acetylene reduction activity of nodules showed a sharp decrease within 4 hours of the treatment. Detopping at the 10th and 14th hours resulted in a 90 % decrease in the nitrogenase activity over the control. However, the same treatments resulted in only a 10–15 % decrease in nodule soluble carbohydrates, reducing sugars and starch content. Nodule respiration, however, showed a decline almost parallel to nitrogen fixation (correlation coefficient = 0.9) upon detopping. In a short term experiment, decapitation and stem girdling reduced the ARA by 50 and 66 % of the control within 1 hour, respectively. It, therefore, appears from the present investigation that certain unknown mechanism operates which puts a constraint on utilization of carbohydrates for nodule respiration which supports nitrogen fixation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
