An impairment of urea induced root development of paddy (Oryza sativa): an adverse effect of cold acclimation.

Root growth and development is affected by different ways although the mechanism is not clarified. To identify the factors involved in impaired growth, we used pot experiment for cultivation of rice (Oryza sativa) and examined the effects of cold acclimation on urea induced root number, root length and shoot length. The root numbers and root length were severely impaired whenever exposed to cold for 48h and 72h of the treatment while mild effect was observed after 24h duration when compared to the control. Acclimation of cold in presence of urea also reduces the root numbers and root length effectively however, enhanced values were found after 24h of the treatment. To clarify whether, plant growth is affected by these two effectors; we examined the effects of cold and urea exposure on shoot length and were found to be impaired for prolonged time while the stimulatory effects on shoot length had been found after 24h of the treatment. Our findings demonstrate that prolonged cold acclimation causes the adverse effects on the development of urea induced plant and root growth, however short term acclimation may not impair the urea induced growth of roots.