Molecular marker screening of tomato, (solanum lycopersicum L.) Germplasm for root-knot nematodes (Meloidogyne species) resistance

Tomato is one of the crops in which genetic resistance has specially been effective against root-knot nematodes. In this study, molecular screening was done on some tomato germplasm to detect markers for the gene that confers resistance (Mi) with specific primer (Mi23/F//Mi23/R). The cultivars; VFNT, FLA 505-BL 1172, 2641A, “Adwoa Deede” and Terminator FI showed the marker for the homozygous resistant genotypes (Mi/Mi). The cultivars, Tima and 2644A showed both markers, corresponding to heterozygous resistant genotypes (Mi/mi). Twenty one (21) of the cultivars did not show any of the markers presumably due to non-specificity at the primer-binding sites. Five (5) heterozygous individuals were determined out of 6 resistant cultivars following the Hardy-Weinberg principle in population genetics.Keywords: Germplasm, Meloidogyne incognita, molecular marker, resistance, Solanum lycopersicum

Estimation of heritability and genetic gain in height growth in Ceiba pentandra

Ceiba pentandra (L.) has been selected for plantation establishment in Ghana under the National Forest Plantation Development Programme of Ghana (NFPDP). This has led to a rise in demand for its seedlings for large scale commercial plantation establishments with seed of C. pentandra being collected from the wild and used to raise seedlings to meet the demands of the programme. The primary purpose of most of these plantations is timber with height growth as one of the key economic traits. However, there is relatively inefficient information available on the heritability and genetic gain in height growth in C. pentandra based on which selection and subsequent breeding could be made. This poses a major challenge to the production of new cultivars for the forestry industry of Ghana. The current study looked at the estimation of narrow sense heritability (h2) and genetic gain in height growth in C. pentandra using 37 accessions from Ghana. Narrow sense heritability was 0.56 and genetic gain in height ranged from -52.82 to 37.30 cm/yr. Twenty-two (22) accessions (59.46%) had mean height increment above the overall mean performance and were recommended for conservation as seed trees. The results were discussed in relation with the conservation of C. pentandra genetic resources and the potential of accessions for high genetic gains.Key words: Ceiba pentandra, narrow sense heritability, genetic gain, height growth, stem dieback disease

Genotype by environment interaction and stability of extra-early maize hybrids (Zea Mays L.) for yield evaluated under irrigation.

Maize (Zea mays L.) is the most important cereal crop produced in Ghana. However the change in environmental conditions, the expansion of maize to new agro-ecologies coupled with inadequate maize varieties available for the different environments affects yield improvement programmes in Ghana. Hence, the study is to investigate the influence of genotype by environment interaction on the maize hybrids and to identify stable and high yielding hybrids with superior agronomic for famers use in the country. The objectives of the study was to investigate the influence of genotype by environment interaction on the maize hybrids and to identify stable and high yielding hybrids with superior agronomic performance for famers use in Ghana. Thus, fifteen extra-early maize hybrids and three locally released checks were evaluated in a randomized complete block design with three replications in two locations in Ghana. The experiment was carried out at KNUST and Akomadan which represent the forest and forest transition zones of Ghana. Nine of the hybrids out of the fifteen hybrids evaluated produce above the average yield and the effect of genotype, location and genotype by location interaction was significant for grain yield. The GGE biplot used in this study revealed that TZEEI-1 x TZEEI-21, TZEEI-6 x TZEEI-21, TZEEI-15 x TZEEI-1 and TZEEI-29 x TZEEI-21 were high yielding and stable hybrids because they were closer to the ideal. The GGE biplot also identified Akomadan as the most ideal testing environment for these hybrids under irrigation

Evaluation of tomato genotypes for resistance to root-knot nematodes

Tomato ( Solanum lycopersicum ) is one of the most popular vegetable crops worldwide, owing to its high nutritive value and diversified use. Tomato production in Ghana is threatened by plant parasitic nematodes, especially the root knot nematodes ( Meloidogyne spp.), which are responsible for huge economic yield losses. The losses, however, can be averted through use of resistant varieties. A study was conducted to evaluate tomato genotypes reaction to root-knot nematodes. Five inoculum levels, 100, 500, 1000, 1500 and 2000 root-knot nematode eggs per 1.6 litres of soil per pot were inoculated on tomato seedlings. A total of 33 genotypes were screened for resistance to Meloidogyne spp. Nine tomato genotypes were collected from Burkina Faso, eight from Vietnam, seven from the United States of America, three genotypes from South Africa, and six from local agro-dealers and farmers in Ghana. The genotypes were screened in pots and the field for host resistance to Meloidogyne spp. The 1500 eggs per plant inoculation level resulted in the highest number of eggs, juveniles and fresh root weight. Among the 33 genotypes screened, Tomato Mongal T-11 and Tomato Beef Master were found to be highly resistant to Meloidogyne spp. and also recorded the lowest reproductive factors of 0.71 and 0.53, respectively.La tomate ( Solanum lycopersicum ) est une des plus populaires l\ue9gumes au monde suite \ue0 sa valeur plus nutritive et utilisation diversifi\ue9e. Par ailleurs, sa production est limit\ue9e par des n\ue9matodes parasites des plantes, sp\ue9cialement les galles racinaires ( Meloidogyne spp.) et sont responsables de lourdes pertes \ue9conomiques. Ces pertes, par ailleurs, peuvent \ueatre \ue9vit\ue9es par l\u2019utilisation des vari\ue9t\ue9s r\ue9sistantes. Une \ue9tude \ue9tait conduite pour \ue9valuer la r\ue9action des g\ue9notypes de tomates aux galles racinaires des n\ue9matodes. Cinq niveaux d\u2019inoculum \ue0 savoir 100, 500, 1000, 1500 et 2000 galles d\u2019oeufs de n\ue9matodes par 1.6 litres de sol par pot \ue9taient inocul\ue9s sur les plantules de tomates. Un total de 33 g\ue9notypes \ue9taient r\ue9sistants au Meloidogyne spp. Neuf g\ue9notypes de tomates \ue9taient collect\ue9s du Burkina Faso, huit du Vietnam, sept des Etats Unis d\u2019Am\ue9rique, trois g\ue9notypes d\u2019Afrique du Sud et six provenant des vendeurs et fermiers locaux du Ghana. Les g\ue9notypes \ue9taient test\ue9s en pots et en champ pour r\ue9sistance de l\u2019 h\uf4te au Meloidogyne spp. Les 1500 oeufs par niveau d\u2019inoculation de plants ont induit un nombre le plus \ue9lev\ue9 d\u2019oeufs, raciness juveniles et le poids des racines fra\ueeches. Parmi les 33 g\ue9notypes test\ue9s, Tomato Mongal T-11 et Tomato Beef Master ont \ue9t\ue9 trouv\ue9s les plus r\ue9sistantes au Meloidogyne spp. et avaient aussi enregistr\ue9 les facteurs les moins reproductifs de 0.71 and 0.53, repectivement

Phenotype and molecular characteriacion of released sweetpotato varieties and pathogen-tested putative ramets in Ghana.

Officially released varieties in Ghana are all selections from exotic introductions. Following release, no effort was made to maintain pathogen-tested foundation seed stocks. Pathogen-tested plants of 4 released varieties were introduced to Ghana and compared with released varieties to confirm a) that they were the same varieties and b) to evaluate whether pathogen-tested planting material of these varieties could be used to increase yield and quality. Planting material of cultivars and introduced pathogen-tested materials of the same genotypes were field multiplied at Fumesua, Ghana, before planting in replicated trials at 2 locations during the 2011 growing season. Standard morphological descriptors and molecular markers were used to assess equality of genotypes, while yield and virus symptoms during growth were used to determine benefits of using pathogen-tested planting material. Morphologically, Otoo and Sauti were more similar to their putative ramets than Faara and Okumkom. Mogamba, the putative ramet of Otoo, recorded the highest yield among the pathogentested clones at the two locations, while also expressing low virus symptoms. Otoo also had the highest yield and lowest virus ratings among the released varieties. Tanzania a pathogen tested ramet of Sauti had the worst virus score across locations. TIS 3017 (CIP 440064), the pathogen-tested putative ramet of Faara did not yield well though it did not express severe virus symptoms

Evaluation of Maize Top Cross Hybrids for Grain Yield and Associated Traits in Three Agro-Ecological Zones in Ghana

Maize (Zea mays L.) is an important food crop in Ghana, but its productivity in farmers‟ fields throughout the country is generally low. The low grain yields can be attributed partly to the use of traditional low-yielding open-pollinated varieties. In an attempt to increase maize productivity, 39 top cross hybrids were developed using 21 inbred lines and 3 open-pollinated varieties. The trial was set up in a randomized complete block design with two replications in three locations in southern Ghana. The overall objective of the study was to investigate traits which influence yields in top cross hybrids and to ascertain the yield potential of the hybrids in three agro-ecological zones in Ghana. The Genotypes were evaluated to determine agronomic performances and correlations between yield and yield component traits were calculated to assess the degrees of associations. Highly significant variations (

Occurrence of cowpea viruses in the forst and savannah agro-ecological zones of Ghana

Cowpea ( Vigna unguiculata (L.) Walp) is a major grain legume in Sub Saharan Africa whose production is heavily affected by viral diseases. A disease survey and antigen-coated plate enzyme-linked immunosorbent assay (ACP-ELISA) were used to determine the incidence, severity and occurrence of viruses infecting cowpea in some major growing areas in the Ashanti and Brong Ahafo regions of Ghana. The survey revealed the highest virus incidence (81.6%) and severity (3.01) in Ejura, and the least incidence (46.7%) and severity (2.38) in Nkoranza. The ACP-ELISA results indicated that Blackeye cowpea mosaic virus (BICMV) was the most prevalent virus, with occurrence ranging from 32% in Mampong to 60% in Atebubu. Cucumber mosaic virus (CMV) was the least detected, occurring only in samples from Nkoranza (4%). Cowpea mild mottle virus (CPMMV), Cowpea mottle virus (CPMoV), Southern bean mosaic virus (SBMV), Cowpea aphid borne mosaic virus (CABMV) and Cowpea yellow mottle virus (CYMV) were also detected in the samples. The prevalence of these viruses suggest the need for continuous monitoring of cowpea fields in the country to ensure effective disease management.Le ni\ue9b\ue9 ( Vigna unguiculata (L.) Walp) est une l\ue9gumineuse \ue0 grains majeure en Afrique SubSaharienne dont la production est fortement affect\ue9e par les maladies virales. Une enqu\ueate sur la maladie et un test d\u2019immunosorbant enzymatique sur plaque rev\ueatue d\u2019antig\ue8ne (ACP-ELISA) ont \ue9t\ue9 utilis\ue9s pour d\ue9terminer l\u2019incidence, la gravit\ue9 et la fr\ue9quence des virus infectant le ni\ue9b\ue9 dans certaines grandes zones de culture des r\ue9gions d\u2019Ashanti et de Brong Ahafo au Ghana. L\u2019enqu\ueate a r\ue9v\ue9l\ue9 l\u2019incidence du virus (81,6%) et la gravit\ue9 (3,01) les plus \ue9lev\ue9es \ue0 Ejura, et la moindre incidence (46,7%) et la gravit\ue9 (2,38) \ue0 Nkoranza. Les r\ue9sultats ACP-ELISA ont indiqu\ue9 que le virus de la mosa\uefque du ni\ue9b\ue9 aux yeux noirs (BICMV) \ue9tait le virus le plus r\ue9pandu, avec une occurrence allant de 32% \ue0 Mampong \ue0 60% \ue0 Atebubu. Le virus de la mosa\uefque du concombre (CMV) a \ue9t\ue9 le moins d\ue9tect\ue9, et il ne s\u2019est que\ua0pr\ue9sent\ue9 dans des \ue9chantillons de Nkoranza (4%). Le virus de la marbrure l\ue9g\ue8re du ni\ue9b\ue9 (CPMMV), le virus de la marbrure du ni\ue9b\ue9 (CPMoV), le virus de la mosa\uefque du haricot m\ue9ridional (SBMV), le virus de la mosa\uefque du puceron du ni\ue9b\ue9 (CABMV) et le virus de la marbrure jaune du ni\ue9b\ue9 (CYMV) ont \ue9galement \ue9t\ue9 d\ue9tect\ue9s dans les \ue9chantillons. La pr\ue9valence de ces virus sugg\ue8re la n\ue9cessit\ue9 d\u2019une surveillance continue des champs de ni\ue9b\ue9 dans le pays pour assurer une gestion efficace de la maladie

GENETIC ANALYSIS OF YIELD AND YIELD COMPONENTS IN Oryza sativa x Oryza sativa CROSS

The number one goal of most rice improvement programmes around the world is breeding for high potential to take care of the increasing consumption of rice. The objective of this experiment was to study the inheritance of yield and yield components and to estimate the heritabilities of important quantitative traits in rice (Oryza sativa L.). Six generations viz., P1, P2, F1, F2, BCP1 and BCP2 of a cross between IET6279 and IR70445-146-3-3 were used for the study. Generation mean analysis suggested that additive effects had a major role for the expression of plant height, number of panicles, number of spikelets per panicle, percentage spikelets fertility per plant and grain yield per plant, which further suggested that phenotypic selection was possible at an early stage. Both additive and non-additive gene actions were important for the expression of number of fertile spikelets per panicle and 100-grain weight. Therefore, selection for these characters would be fruitful, if delayed till epistasis effects are reduced to a minimum. High broad sense heritability estimates were observed for characters viz. plant height and 100-grain weight, suggesting that the characters under study are less influenced by environment in their expression. Thus, selection based on phenotypic value of these characters would be reliable and effective. Low estimates of broad sense heritability were observed for number of panicles per plant, number of spikelets per panicle, number of fertile spikelets per panicle, percentage spikelets fertility per plant and grain yield per plant, indicating that influence of the environment was high for these characters. Therefore, superior genotypes selection based on phenotypic performance for these characters may not effective.La majorit\ue9 des objectifs des programmes d\u2019am\ue9lioration du riz dans le monde est relative \ue0 la s\ue9lection pour le d\ue9sire croissant de la consommation du riz. L\u2019objectif de cette exp\ue9rimentation \ue9tait d\u2019\ue9tudier l\u2019h\ue9ritage du rendement et des composantes du rendement et d\u2019estimer les h\ue9ritabilit\ue9s des traits importants sur le riz (Oryza sativa L.). Six g\ue9n\ue9rations viz, P1, P2, F1, F2, BCP1 et BCP2 du croisement entre IET6279 et IR70445-146-3-3 \ue9taient utilis\ue9s pour cette \ue9tude. L\u2019analyse de la moyenne des g\ue9n\ue9rations a sugg\ue9r\ue9 que les effets additifs ont un r\uf4le majeur pour l\u2019expression de la taille de la plante, le nombre de panicules, le nombre d\u2019\ue9pillets par panicule, le pourcentage de fertilit\ue9 d\u2019\ue9pillets par plant et le rendement en grain par plant qui davantage ont sugg\ue9r\ue9 que la s\ue9lection ph\ue9notypique \ue9tait possible \ue0 une \ue9tape pr\ue9coce. Les actions de g\ue8nes de type additifs et non-additifs \ue9taient importantes pour l\u2019expression du nombre d\u2019\ue9pillets fertiles par panicule et le poids de 100-grains. Toutefois, la s\ue9lection pour ces caract\ue8res serait utile\ua0; si elle est retard\ue9e jusqu\u2019\ue0 ce que les effets d\u2019\ue9pistasis soit r\ue9duits au minimum. La valeur \ue9lev\ue9e de la grande h\ue9ritabilit\ue9 \ue9tait observ\ue9e pour les caract\ue8res viz. La taille de la plante et le poids de 100 grains, sugg\ue9raient que les caract\ue8res sous investigation sont moins influenc\ue9s par l\u2019environnement dans leur expression. Donc, la s\ue9lection bas\ue9e sur les valeurs ph\ue9notypiques de ces caract\ue8res serait plus efficace. De faibles valeurs estim\ue9es de la grande h\ue9ritabilit\ue9 \ue9taient observ\ue9es pour le nombre panicules par plant, nombre d\u2019\ue9pillets par panicule, nombre d\u2019\ue9pillets fertiles par panicule, le pourcentage d\u2019\ue9pillets fertiles par plant et le rendement en grain par plant, indiquant que l\u2019influence de l\u2019environnement \ue9tait \ue9lev\ue9e pour ces caract\ue8res. Toutefois, la s\ue9lection sup\ue9rieure des g\ue9notypes bas\ue9e sur la performance ph\ue9notypique pour ces caract\ue8res pourrait \ueatre non efficiente

HYBRIDISATION BETWEEN CHERRY TOMATO (SMALL FRY) AND PETOMECH FOR SHORTENED FRUIT MATURATION, SIZE AND EARLINESS

Tomato ( Lycopersicon esculentum var. cerasiforme ) is among the most important vegetable crops grown world wide providing good nutritional requirements and boost incomes, especially in sub-Saharan Africa. The objective of this study was to determin the heritability of shortened fruit maturation (SFM) period in a hybrid from a cross between cherry (Small fry) tomato and Petomech. A field experiment was carried out at the Crops Research Institute (CRI), Kwadaso. A cross was made between Petomech and Small fry. Fruit maturation period (FMP) (days from anthesis to the breaker stage of fruit Colour) was 42 days for Small fry and 52 days for Petomech. Parental, F1, F2, and backcross generations differed in FMP, yield, estimates of broad- and narrow-sense SFM heritabilities of 61.4 and 38.8%, respectively, on a single-plant basis. A test for midparent heterosis also showed significance (P<0.05). Genetic control of SFM was quantitative in nature, and highly dominant. The F1 and F2 generations had FMP of 47.2 and 49.5 days, respectively. F1, F2, and backcross generations all differed in number of fruits per plant, giving broad- and narrow-sense heritabilities of 69.73 and 55.67%, respectively. With a mean per fruit weight of 150.1 g Petomech recorded the highest fruit weight, while Small Fry recorded the lightest fruit weight of 81.4 g. Estimated broad-and narrow sense heritability for fruit weight was 71.76 and 41.68%, respectively. There was a significant difference between Small Fry and Petomech, as well as the BC1 and BC2 in terms of fruit size. The highest heterotic effect was found in number of fruits per plant (27.6%) over mid-parent. The highest yield was recorded by Petomech (18.9 t ha-1), while Small Fry recorded the lowest value of (14.3 t ha-1).La tomate ( Lycopersicon esculentum var. cerasiforme ) est l\u2019une des plus importantes cultures maraich\ue8res de par le monde, contribuant \ue0 satisfaire les besoins nutritionels de l\u2019homme et g\ue9n\ue9rant des revenus aux producteurs, en Afrique au sud du Sahara en particulier. L\u2019objectif de cette \ue9tude \ue9tait de determiner l\u2019h\ue9ritabilit\ue9 du court cycle de maturation (SFM) dans un hybride obtenu du croisement entre la tomate cerise et Petomech. Une experimentation en plein champ a \ue9t\ue9 conduite \ue0 l\u2019institut de recherch\ue9 sur les cultures (CRI) \ue0 Kwadaso. Un croisement a \ue9t\ue9 r\ue9alis\ue9 entre Petomech et la petite tomate cerise. La p\ue9riode de maturation des fruits (FMP) \ue9tait de 42 jours pour la tomate cerise et 52 jours pour Petomech. Les parents, les F1, les F2, et les g\ue9n\ue9rations diff\ue9raient de par leur FMP, leur rendements, les valeurs d\u2019 h\ue9ritabilit\ue9s au sens large et au sens strict de leurs SFM. Ces valeurs \ue9taient respectivement de 61.4 et 38.8%, et ceci sur la base de plante unique. Le test d\u2019h\ue9t\ue9rosis par rapport \ue0 la moyenne des parents \ue9tait aussi significatif (P<0.05). le control g\ue9n\ue9tique de SFM \ue9tait de nature quantitative, et largement dominant. Les g\ue9n\ue9rations F1 et F2 avaient respectivement une FMP de 47.2 et 49.5 jours. Les g\ue9n\ue9rations F1, F2 et backcross diff\ue9raient de par leur nombre de fruits par plante, donnant ainsi des valeurs d\u2019h\ue9ritabilit\ue9s au sens large et au sens strict de 69.73 et 55.67%, respectivement. Petomech a exhib\ue9 les fruits les plus lourds (150.1 g), tandis que la tomate cerise a exhib\ue9 les fruits les plus l\ue9gers (81.4 g). Les valeurs estim\ue9es d\u2019h\ue9ritabilit\ue9 au sens large et au sens strict \ue9taient respectivement de 71.76 et 41.68% pour le poids du fruit. Une difference significative a \ue9t\ue9 observ\ue9e entre les deux parents, ainsi que les g\ue9n\ue9rations backcross BC1 et BC2 , en ce qui concerne la taille des fruits. L\u2019effet h\ue9t\ue9rotique le plus \ue9lev\ue9 \ue9tait observ\ue9 au niveau du nombre de fruits par plante (27.6%) par rapport \ue0 la moyenne des parents. Le rendement le plus \ue9lev\ue9 \ue9tait enregistr\ue9 chez Petomech (18.9 t ha-1), tandis que la tomate cerise avait le plus petit rendement (14.3 t ha-1)

Assessment of Genotype by Environment interactions and Grain Yield Performance of Extra-Early Maize (Zea Mays L.) Hybrids

Maize (Zea mays L.) is one of the most important cereal crops of Ghana in terms of production and consumption. Currently, it is produced in all the agro-ecological zones of the country. In Ghana, Genotype by Environment interactions (GxE) effects on maize grain yield is usually significant due to the diverse environmental conditions at growing sites. A proper understanding of the effects of GxE on variety evaluation and cultivar recommendations is vital. The study was conducted in 2011 at three locations in Ghana to (i) determine the presence of GxE of 100 extra-early maize genotypes and (ii) To use the GGE biplot methodology to determine grain yield performance and stability of the genotypes evaluated across three environments. The effects of genotype and environment were significant (P < 0.01) for grain yield. However, GxE was not significant for the same trait. TZEEI 8 x TZEEI 51, TZEEI 5 x TZEEI 53, TZEEI 21 x TZEEI 39, TZEEI 27 x TZEEI 36 and TZEEI 4 x TZEEI 6 were identified as high yielding and most stable hybrids. Therefore, these hybrids have the potential for production across the test locations as well as others within the same agro-ecological zones. On the contrary, DODZI, TZEEI 23 x TZEEI 6, TZEEI 19 x TZEEI 24, TZEEI 11 x TZEEI 24 and TZEEI 20 x TZEEI 39 were not only low yielding but also among the least stable genotypes. Keywords: Zea mays, single-cross, stability, multiple environments, Gx