Differential Occurrence of Cuticular Wax and Its Role In Leaf Tissues of Three Edible Aroids of Northeast India

Localization of cuticular wax (CW) on the leaf epidermis and its interaction with physiological mechanisms of three edible aroids, Alocasia, Colocasia, and Xanthosoma, were assessed. Scanning electron microscopy depicted the occurrence of CW in the leaf tissues, which was higher in Colocasia (10.61 mg dm-2) and Xanthosoma (11.36 mg dm-2) than in Alocasia (1.36 mg dm-2). Higher CW in Colocasia and Xanthosoma strengthened leaf epidermis and improved the physiological processes compared to Alocasia. CW acted as a protecting barrier against deleterious solar radiation in terms of sun protection factor (SPF). The glossy appearance of wax crystals in the Alocasia leaf cuticles resulted in higher SPF. The occurrence of CW was directly related to leaf chlorophyll stability, moisture retention ability, and cellular membrane integrity in the leaf tissues. Colocasia exhibited superhydrophobic properties with higher static contact angle (CA) >150o than hydrophobic Xanthosoma, and Alocasia with CA ranged between 99.0o to 128.7o. Colocasia CW highly influenced the qualitative and protective mechanisms of the leaf. Aroids are the cheapest sources of edible CW among the terrestrial plants, which could be used in food, agricultural and industrial applications.

Differential Occurrence of Epicuticular wax and its Role in Leaf Tissues of Three Edible Aroids Hails from North Eastern Hill Region of India

Localization of epicuticular wax (EW) content in leaf tissues and its interaction on leaf protective mechanisms of three edible aroids, Alocasia, Colocasia and Xanthosoma were assessed. Scanning electron microscopy depicted the occurrence of EW in leaf tissues which was higher in Colocasia (10.61 mg dm-2) and Xanthosoma (11.36 mg dm-2) than in Alocasia (1.36 mg dm-2). The result highlighted the interface of EW between the leaves and its internal and external environments. EW acted as a protecting barrier against deleterious solar radiation in term of sun protecting factor (SPF). Occurrence of EW also effectively managed leaf pigmentation, moisture retention, cellular membrane integrity against the invaders. Colocasia exhibited superhydrophobic properties with higher static contact angle (CA) >150o than hydrophobic Xanthosoma and Alocasia with CA ranged between 99.0o to 128.7o. Colocasia EW highly influenced the qualitative and protective mechanisms of leaf. Aroids are the cheapest sources of edible EW among the terrestrial plants could be used in food, agricultural and industrial applications.

Mitotic Studies and Genotoxic Assessment of Edible Nigerian Aroids to Selected Oilfield Chemicals

The genotoxic potentials of two water-based oilfield chemicals on edible aroids were investigated. Five accessions of Colocasia eculenta and three accessions of Xanthosoma maffafa were exposed to graded concentrations of sodium azide and potassium chromate; while the accessions without any chemical additive were used as controls. Results revealed that the peak periods of cell division were recorded between 12:00 noon to 4:00 pm in both the treated and control accessions. Metaphase cells increased after prophase cells and continued mostly between 10.00 am and 4.00 pm. Variations observed with the treatments included: shifts of metaphase peaks, high percentages of prophase cells, high intensity of cytoplasmic staining and induction of micronuclei among others. Sodium azide was observed to be a stronger genotoxic substance than potassium chromate. Accession NCe 001 had the highest survival rate while NCe 002 recorded the least rate of survival. Statistical evidence revealed that the difference in various mitotic stages and time of harvest between different accessions and treatments was significant at both 5% and 1%. The study provides useful information that would be used to promote cytogenetic researches as well as the exploitation and improvement of this neglected and underexploited economic plant.

Genetic variability of Colocasia esculenta (L.) Schott.

Studies on the nature and extent of variability of aqua edible aroids cultivars, Colocasia esculenta (L.) Schott. revealed significant differences and wide range of variations among the accessions and cultivars. Genotypic variances and coefficient of variation for most of the characters were remarkably higher than their corresponding variances due to environment which also indicate the existence of variation in genotypic origin. Plant height, petiole length, leaf length, each stolon weight, total stolon weight, stolon length and corm length expressed high heritability with moderate to high genetic advance signaled heritable in nature. Key words: Genetic variability; Heritability; Colocasia esculenta; Genetic advance DOI: http://dx.doi.org/10.3329/bjb.v40i2.9775 Bangladesh J. Bot. 40(2): 185-188, 2011 (December)