OPTIMAL CONDITIONS FOR MAXIMUM MITOTIC INDEX IN ONION ROOT TIPS: INFLUENCE OF HARVESTING TIME AND ROOT AGE IN LABORATORY SETTINGS

Abstract

Utilizing the actively growing root tips of onions and sprouting lentils has become a standard practice in science laboratories for elucidating the various stages of mitotic cell division. Though the technique is widespread with well-established protocols, we noted inconsistencies in the distribution of cell division stages during morning and afternoon sample preparation done for lab practical sessions. This led us to investigate whether specific factors, such as the time of day or the age of the root, influence theprevalence of different mitotic stages. In this study, we sought to standardize the harvesting time, and age of onion root tips to obtain a maximum mitotic index. The roots were stained and meticulously observed three times a day from day 1 to 9 since root induction. Concurrently, root growth parameters were also recorded. There was no notable distinction in the mitotic index across days for both red onions and shallots. We noted a substantial presence of mitotic stages on day 6 in red onions. Frequency of mitotic stages were comparatively higher in the morning than afternoon and evening. Our findings indicate that the best time for observing peak mitotic stages is during the mornings of days 5 through 7.