Variability of yield and yield components in "Egusi" melon

Egusi melon ( Citrullus lanatus (Thunb.) Mansf.) is an important food crop in Nigeria and other African countries. In a study carried out to estimate the components of variation in \u2032egusi\u2032 melon populations indicated high proportion of genetic variation in the yield attributes measured. Estimates of phenotypic coefficient of variation ranged between 3.6-52%, while genotypic coefficient of variation ranged between 3.21-51% for seed yield plant -1 , number of fruits plant -1 and fruit yield plant -1 . Heritability estimate was high in the yield attributes. On seed yield plant -1 , heritability ranged between 83-98%. Estimate of expected genetic advance in seed yield plant -1 ranged between 25.90-48.40%. Improvement could be made in seed yield through selection.Le melon \u201cEgusi\u201d ( Citrullus lanatus (Thunb.) Mansf.) est une important culture alimentaire au Nigeria et autres pays africains. Une \ue9tude port\ue9e sur l\u2019estimation des composants de variation des populations du melon \u201cEgusi\u201d avait indiqu\ue9 une proportion \ue9lev\ue9e de la variation g\ue9n\ue9tique dans les caract\ue9ristiques mesur\ue9es. Pour le rendement en grain et le nombre de fruits par plant, le coefficient de variation ph\ue9notypique et g\ue9notypique variait de 3.6-52% et de 3.21-51% respectivement. L\u2019estimation de l\u2019h\ue9ritabilit\ue9 \ue9tait \ue9lev\ue9e dans les param\ue8tres de rendement avec des valeurs d\u2019h\ue9ritabilit\ue9 variant entre 83et 98% pour le rendement en grain par plant. L\u2019estimation de l\u2019am\ue9lioration g\ue9n\ue9tique expect\ue9e du rendement en grain par plant variait entre 25.90-48.40%. L\u2019am\ue9lioration du rendement en grain pourrait \ueatre faite sur base de s\ue9lection

Selection of maize genotypes resistant to pink stem borer and sugarcane borer.

Maize is an important economic crop grown in Nigeria. Its production is dramatically affect by the pink stem borer—Sesamia calamistis (Hampson, Noctuidae) and sugarcane borer—Eldana saccharina (Walker, Pyralidae) that are endemic in Southeastern Nigeria. In areas of stress, existing genotypes may marginally do well due to their inherent capabilities. Therefore, it is possible to find useful genes in such areas of stress, since such genes have been responsible for the survival of host crops over the years. Evaluation study was conducted for a range of agronomic characteristics and resistance attributes for 209 local maize collections from Southeastern Nigeria along with three improved check varieties. Field trials were conducted at three locations in a total of four environments in 2001. Highly significant genotypic variances as were noted in all the traits, are indicative of the magnitude of variation that exists among the genotypes, thus providing the opportunity of selection for desirable traits. Furthermore, four traits, namely, leaf feeding, ear damage, stalk lodging and yield were used from across the environments to construct a rank summation index (RSI), which was used to rank the entries for resistance to stem borers. This RSI led to the identification of 11genotypes which represents the best 5% of the 212 genotypes in resistance ability. Genotype AMA TZBR-WC1 (from International Institute of Tropical Agriculture (IITA), Ibadan) had the best overall resistance levels, followed by genotypes SE NG-77 and SE NG-67 (from Umuahia North), SE NG-62 (from Ikwuano), SE NG-148 (from Ukwa West), SE NG-106 (from Bende), SE NG-119 (from Isiala Ngwa), SE NG-33 (from Ikwuano) and SE NG-65 (from Umuahia North)

Variability of yield and yield components in "Egusi" melon

Egusi melon ( Citrullus lanatus (Thunb.) Mansf.) is an important food crop in Nigeria and other African countries. In a study carried out to estimate the components of variation in ′egusi′ melon populations indicated high proportion of genetic variation in the yield attributes measured. Estimates of phenotypic coefficient of variation ranged between 3.6-52%, while genotypic coefficient of variation ranged between 3.21-51% for seed yield plant -1 , number of fruits plant -1 and fruit yield plant -1 . Heritability estimate was high in the yield attributes. On seed yield plant -1 , heritability ranged between 83-98%. Estimate of expected genetic advance in seed yield plant -1 ranged between 25.90-48.40%. Improvement could be made in seed yield through selection.Le melon “Egusi” ( Citrullus lanatus (Thunb.) Mansf.) est une important culture alimentaire au Nigeria et autres pays africains. Une étude portée sur l’estimation des composants de variation des populations du melon “Egusi” avait indiqué une proportion élevée de la variation génétique dans les caractéristiques mesurées. Pour le rendement en grain et le nombre de fruits par plant, le coefficient de variation phénotypique et génotypique variait de 3.6-52% et de 3.21-51% respectivement. L’estimation de l’héritabilité était élevée dans les paramètres de rendement avec des valeurs d’héritabilité variant entre 83et 98% pour le rendement en grain par plant. L’estimation de l’amélioration génétique expectée du rendement en grain par plant variait entre 25.90-48.40%. L’amélioration du rendement en grain pourrait être faite sur base de sélection

Implications of polyembryony on the growth and yield of fluted pumpkin (Telfairia occidentalis hook. f.)

Two experiments were conducted during the wet seasons of 2004 and 2005 to investigate the performance of polyembryonic lines with respect to growth and yield of fluted pumpkin. The results revealed three morphotypes of polyembryony, namely: twin (bi-embryony), triple (tri-embryony) and quadruple (tetra-embryony). In the first year (2004), the triple and quadruple embryo types had the highest (54.52%) and lowest (2.02%) frequencies of occurrence, respectively. In the second year (2005), the frequencies of the triple and quadruple embryo types were 60.99% and 4.78%, respectively. There was no clear trend across all the embryo types investigated with respect to the characters measured. However, generally, the triple and the single (mono-embryony) lines performed better than the twin and quadruple lines. The impressive performance of the single and triple embryo types over the twin and quadruple embryo types with respect to the weight of pods, in 2004 and 2005 suggests that these embryo types are good candidates multiplication and distribution to farmers using the micropropagation technique.Key words: Polyembryony, growth, yield, fluted pumpkin, Telfairia occidentalis

Ploidy and genome segregation in Musa breeding populations assessed by flow cytometry and randomly amplified polymorphic DNA markers

The majority of edible bananas (Musa L.) are triploid (2n = 3x = 33) cultivars known as dessert, plantain, or cooking bananas with predominant AAA, AAB, and ABB genomes, justifying the aim of breeding programs to develop improved hybrids of the different utilization classes in the triploid background. This usually involves crossing 3x landraces to 2x accessions that are donors of resistance genes, selecting 4x and 2x primary hybrids from the 3x-2x progenies, and crossing 4x-2x hybrids to produce secondary 3x hybrids. Ploidy and genome segregation routinely occurs during this process and constitutes a major hindrance for selection because this is not easily detectable at the morphological level. This study was carried out to assess the potential of early screening for discriminating ploidy and genome classes in 4x (AAAB)-2x (AA) breeding populations, based on flow cytometry and genome-specific RAPD analysis. Results indicate that progenies of 4x-2x crosses produced predominantly 3x progenies (94.1%). RAPD analysis identified seven genomic classes, dominated by AAA and AAB configurations segregating 1:1 (χ2 = 0.21, P = 0.05). Plant size and bunch weight increased with ploidy level, justifying ploidy-based grouping of progenies for homogenous field evaluation. Similarly, genome-based grouping within ploidy classes is recommended to allow proper evaluation of progenies according to targeted postharvest utilization. Thus, ploidy analysis by flow cytometry and genome determination by RAPD open prospects for enhancing breeding efficiency in the development of triploid bananas or plantains

Growth, yield and disease responses of 12 cassava genotypes evaluated for two cropping seasons in a derived savannah zone of southeastern Nigeria

Ten new cassava genotypes selected for high yield and tolerance to some biotic stresses were evaluated alongside the local best, Otupam and ‘TMS 30572\' (a widely cultivated hybrid genotype, as an improved check) for two cropping seasons with a view to obtaining suitable genotype(s) that could be recommended for release to farmers. The results revealed that only TMS-96/0304, TMS-96/1672 and NR-930255 had above 90% sprout survival at 12 months after planting. Severity of cassava mosaic disease (CMD), cassava anthracnose disease (CAD) and cassava bacterial blight (CBB) varied among genotypes, plant age, and the cropping year. Symptom expressions of CMD and CBB were generally higher on the local best, Otupam and NR-930255. The severity of cassava green mite was moderate and statistically similar on all the genotypes while severity of cassava mealybug was mild. Hybrids NR930255, TMS96/1672 and TMS96/0304 produced the highest number of tubers. These genotypes also significantly (P< 0.05) produced the highest harvested tuber yield per hectare: NR 930255 (31.0 t/ha), TMS 96/1672 (28.0 t/ha) and TMS 96/0304 (29.4 t/ha). The three genotypes had the least percent yield difference between the potential and the actual yield. Mean rank-sum for all traits measured suggested that the most adaptable genotypes to Nsukka agro-ecology after two years of evaluation were NR-930255, TMS 96/0304 and TMS96/1672, but the poor disease ratings for NR-930255 and TMS 96/0304 precluded their recommendation for release while TMS 96/1672 could be recommended for release to farmers