Characterization of Growth and Maturity Period in Gossypium arboreum by the Plastochron Index

Growth characterization of four field grown cotton genotypes was done using the plastochron index. The crop was in juvenile phase up to PI 15.48 for which 45 days were required. It required additional developmental age of PI 8.10 for expressions of flowering after completion of juvenility, whereas 4.54 more PI were required for period between flowering to its maturity. The crop exhibited simultaneous expression of vegetative as well as reproductive growth. This concurrent period was 127 days, there was a gap of 77 days from 1^st boll maturity to overall maturity. During this period the developmental age was advanced by 9.82 PI. The overall maturity was achieved within 185 days during which total plastochron development was 40.95 PI. Thus, period for juvenility and the length of period for 1^st maturity to overall maturity appeared to be responsible for major variation in maturity period of cotton. These two components can be employed for screening the genotypes for maturity period in cotton.