Growth analysis studies in onion (Allium cepa L)

An investigation on growth analysis was conducted with ten varieties/lines of onion at the experimental plot, Division of  Vegetable Crops, Indian  Agricultural research institute, New Delhi to study the growth patterns at 45, 60, 75, 90 and 105 days after transplanting (DA T).  There was a wide variation among genotypes for all the growth parameters during the growth stages. The most decisive period for onion plant to fix the bulb weight, bulb diameter and ultimately the yield is the period between 45 and 90 DAT. Net assimilation rate (NAR), relative growth rate (RGR) and leaf area ratio (LAR) were high in earlier days therefore more attention is needed at 45 and 60 DA T. Breeding for physiological traits should be taken care and the early rapid growth during 45 to 75 DA Twill be helpful to increase the production and productivity of onion.  Yield contributing characters like bulb weight, bulb diameter (horizontal and vertical), plant height, leaf area and total chlorophyll content are the most dependable characters and could be effectively used in breeding for improvement in yield in onion.