National Research Centre for Groundnut, Junagadh (Gujarat).
The arrangement of vegetative and reproductive nodes were examined on basal, primary and secondary branches of 75 accessions each of Virginia bunch and Virginia runner forms of cultivated peanut (Arachis hypogaea L. ssp. hypogaea Krap. et. Rig. var. hypogaea Krap. et. Greg.). The main axis was devoid of flowers (inflorescences) on all the plants of both the forms. The nodesequence, ingeneral, started with vegetative nodes on primary branches and reproductive nodes on secondary branches in both the forms. There was predominant occurrence of one to five reproductive nodes on secondary branches of both the forms. A few accessions had a continuous sequence of three to five reproductive nodes on secondary branches. On primary branches of Virginia bunchcollection, three alternate irregular pairs of node sequences starting with vegetative nodes were recorded in 43.1% plants followed by four pairs in 25.9% plants, whereas in Virginia runner, four pairs (37.%) followed by three pairs (27.7%) were frequent. On the other hand, one pair starting with reproductive nodes on secondaries was predominant in 74.8% and 68.5% plants, respectively. The regular sequence of two vegetative alternating with two reproductive nodes was found on primaries of only 17.2% and 13.1% plants of Virginia bunch and Virginia runner, respectively. The alternate irregulars equences with all possible combinations numbering 111 on primary branches and 62 on secondaries were found in both the populations and thus, sequences with predominant occurrence could not be spotted. The wide variation for this trait in the sampled population, besides overlapping variation within and between the two forms confirmed that node sequence was controlled by polygenes. This trait may not be suitable for identification of Virginia genotypes in the primary gene pool of cultivated peanuts and also in differentiation between the two forms. The role of node sequence in breeding Virginias was also discussed.
