Corm Length Research Articles

Estimates of Genetic Components for Yield and Related Traits in Cocoyam

In the present investigation attempts were made to estimate genetic parameters for yield and its components in 315 genotypes of cocoyam collected from thirteen aroid growing districts. Plant height, petiole length, petiole breadth, leaf number, leaf length, leaf breadth, LAI, Inflorescence length, peduncle length, spathe length, spathe breadth, corm length, corm breadth, cormel number, cormel length, cormel breadth, corm weight, cormel weight, total fresh weight, total dry weight, yield per plant were taken in this study. Presence of significant differences together with wide ranges of variation indicates wide range of variability existed among the genotypes of cocoyam. Genotypic variances and coefficient of variation for most of the characters were remarkably higher than their corresponding environmental variances, which also indicate the existence of variation in genotypic level. Plant height, petiole length, leaf length, leaf breadth for cocoyam expressed high heritability with moderate to high genetic advance signalled heritable in nature. High heritability with high genetic advance in percentage of mean was also observed for plant height, petiole length, DOI: http://dx.doi.org/10.3329/agric.v10i2.13150 The Agriculturists 2012; 10(2) 127-132

Genetic variability of <i>Colocasia esculenta</i> (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)

Morphological variation and reproductive characteristics of wild giant taro (Alocasia macrorrhizos, Araceae) populations in Vanuatu

This investigation was aimed at understanding the morphological variation and reproductive biology of wild populations of giant taro (Alocasia macrorrhizos) in Vanuatu. It is an aroid species, which grows in vigorous, relatively small and dense populations, consisting of phenotypically uniform or very similar individuals. The most variable traits observed in wild populations are number of inflorescences, number of infructescences per plant, and corm length. These traits are highly variable even within genetically uniform populations and are highly influenced by age differences between plants. Flowering is frequent and most of the plants are highly fertile. However, sexual reproduction is rare due to self‐incompatibility (between plants genetically homogeneous within the same population) and the absence of efficient pollinators. Self‐incompatibility can be partly overcome by repeated self‐pollination. Thermogenesis was studied on a large sample of inflorescences and little variation concerning the thermogenic potential was observed. Our results showed that, despite optimal flowering conditions (concerning pollen fertility, stigma receptivity, and thermogenic potential), propagation of wild Alocasia macrorrhizos populations in Vanuatu was mainly vegetative. Giant taro plants might have been carried beyond the range of their most effective pollinators. Other factors were considered: the presence of numerous earwigs (Labidura truncata) insects within inflorescences, which could have a competing effect with the usual pollinators of giant taro, and the long distances between genetically homogeneous populations.

Heritability of the Main Agronomic Traits of Taro

The increase of production of an important root crop such as taro [Colocasia esculenta (L.) Schott, Araceae] implies the development of new varieties through an efficient breeding scheme. The breeding of new taro cultivars is a complex process which requires experience, adequate genetic resources, and reliable data about inheritance of crucial agronomic traits. To obtain these data, 2‐yr heritability taro trials were conducted in Vanuatu with 42 full‐sib families of variable sizes. In the first clonal generation (C1), a fully randomized complete block design was planted with plots of 16 datum plants. During the second clonal generation (C2), parents were included with their offspring in two alpha incomplete block designs with elementary plots of 12 and 4 datum plants, respectively. Both family and narrow‐sense heritabilities were higher for the number of suckers and dry matter content than for corm weight or its components (corm length and width). A high percentage of valuable hybrids were observed among a small number of families. These results, combined with the moderately high family heritability values for several traits, recommend the creation of a small number of large full‐sib families when working with a narrow genetic base and the creation of numerous small full‐sib families when dealing with a broad genetic base.

Accession Characterization and Genetic Variability Studies in <i>Colocasia esculenta</i> L. Schott

Accessions of Colocasia esculenta L. Schott. cultivars collected from thirteen aroid growing districts were studied for determining their genetic variability under the agromorphological purviews. Plant height, petiole length, petiole breadth, leaf number, leaf length, leaf breadth, LAI, inflorescence length, peduncle length, spathe length, spathe breadth, corm length, corm breadth, cormel number, cormel length, cormel breadth, corm weight, cormel weight, total fresh weight, total dry weight, yield per plant were taken in this study for nature and extent of variability analysis of edible cultivars of Colocasia esculenta L. Schott. Presence of significant differences together with wide ranges of variation in most cultivars indicates wide range of variability existed among the accession as well as local cultivars of this edible aroid. Genotypic variances and coefficient of variation for most of the characters were remarkably higher than their corresponding environmental variances which also indicate the existence of variation in genotypic origin. Key words: Characterization; Mukhikachu; Variability; Corm; Cormel; Colocasia esculenta. DOI: http://dx.doi.org/10.3329/bjsir.v46i2.8191 Bangladesh J. Sci. Ind. Res. 46(2), 235-242, 2011

Studies on Direct and Indirect Effects of Different Plant Characters on Yield of Taro (<i>Colocasia esculenta</i> L. Schott) Var. Antiquorum

Thirty accessions of taro (Colocasia esculenta L) varieties were evaluated to estimate the direct and indirect effects of different plant characters, namely, plant height, petiole length, petiole breadth, leaf number, leaf length, leaf breadth, LAI, inflorescence length, peduncle length, corm length, corm breadth, cormel number, cormel length, cormel breadth, corm weight, cormel weight on yield per plant. Plant height, petiole length, corm breadth, cormel number, cormel length exhibited direct effect on yield per plant at the genotypic level. Cormel weight and cormel breadth had the highest direct effect on yield per plant at the phenotypic level. The residual effect was 0.3043 at the genotypic level and that at phenotypic level was 0.4874. Keywords: Colocasia esculenta; direct effect; indirect effect; yield of taro DOI: http://dx.doi.org/10.3329/agric.v9i1-2.9483 The Agriculturists 2011; 9(1&2): 89-98