Evaluation of Growth and Development of Cassava Plantlets Cultured in vitro Affected by Different Nitrogen Levels

Abstract

The objective of this experiment was to evaluate the cassava plantlet culture system as a tool to obtain the plantlets under the environmental control that will be further used for studying the nutrient uptake genes and genes that may involve. Three cassava varieties (Manihot esculenta Crantz) namely Huaybong 80 (HB80), Kasetsart 50 (KU50) and Rayong 1 (R1) were cultured in MS (Murashige and Skoog, 1962) medium with 5 varied levels of ammoniumnitrate (NH₄NO₃) (0, 10.3, 20.6, 30.9 and 41.2 mM, respectively). Growth and development of plantlet were monitored at 30, 35, 40, 45, 50 and 55 days after culture. Chlorophyll content, fresh weight, dry weight of root, leaf, stem and total fresh and dry weight were measured. The TDW of each variety was maximum at 45 days after culture with 41.2 mM NH₄NO₃ added to the culture medium. HB80 showed greater growth and development in overall when compared to those of KU50 and R1. The TDW of HB80 was statistically higher than those of KU50 and R1 by 9.64% and 1.98% respectively. This was the consequence of greater leaf number, leaf length, stem length, root number and root length of HB80 than the other two. Moreover, the chlorophyll content of HB80 was significantly highest among 3 tested varieties. When compared among the N treatments, it was found that the media containing 41.2 mM NH₄NO₃ (N4) resulted on better growth and development in cassava plantlets in every stages of harvest. The plantlet culture system can be adopted for further use for studying the gene expression affected by different levels of nutrient applications.