Grain yield and oil content of sesame are usually low, depending on genetic
variability and association of relevant characters with grain yield and oil
content. Hence, the objectives of this research were estimating the genetic
variability and association among characters. Eighty one sesame genotypes were
tested in 9x9 simple lattice design at Kebabo Tsegede wereda Western Tigray,
Ethiopia in 2010/11 cropping season. Analysis of variance revealed that there
was highly significant (p<0.01) difference among the 81 genotypes for all
the 15 characters studied. High genotypic and Phenotypic Coefficient of Variation
(PCV) was recorded for harvest index, seed yield/ha, height to first capsule,
biomass/ha, number of capsules/ha, number of primary branches/ha, number of
seeds per capsule and plant height. Height to first capsule had the highest
heritability value. High heritability coupled with high expected genetic advance
as percent of mean was observed for number of primary branches per plant, height
to first capsule and harvest index. This indicates that these characters can
be improved through selection. Harvest index showed positive significant phenotypic
and genotypic correlation with grain yield. Genotypically, path coefficient
analysis based on grain yield as a dependent variable revealed that capsule
filling period by days to 50% flowering and biological yield exerted positive
direct effect on seed yield. Therefore, a greater emphasis should be laid on
these characters in perspective of breeding programs.

Drought and Striga are some of the key constraints to cowpea production. These
are further aggravated by the ever changing global climate and the concomitant
effects such as erratic rainfall pattern. This research was conducted to identify
lines that are tolerant to drought and resistant to Striga in one of
the major cowpea belt in West Africa. Twenty two genotypes of cowpea obtained
from the Cowpea Breeding Programme of the Institute for Agricultural Research
(IAR), Ahmadu Bello University Zaria, Nigeria were evaluated in 2 different
dates; beginning of the rainy season representing optimum moisture (7th August)
and the end of the rainy season representing drought conditions (7th September)
for two years (2008 and 2009). IAR-07-1050 was found to be resistant to Striga
although susceptible to drought (DRI = -0.32). Others genotypes were infested
by Striga. Two genotypes, IT98K-412-13 and IT93K-452-1 with DRI = 1.79
and 1.88, respectively were drought tolerant genotypes. IT99K-529-1, Biu Local,
Kanannado, IT99K-216-24-2, Sa Babba Sata, IT96D-610 and IT97K-819-118 showed
some level of tolerance as indicated by several selection indices including
DRI. These indices were very suitable for the identification of drought tolerance
in cowpea. DRI and DSI are particularly useful in the classification of genotypes
in terms of drought tolerance irrespective of their yield potential. This is
highly desirable for the identification of gene sources for further improvement
of cowpea for drought tolerance or in combination with other traits.

Acacia raddiana (L.) Willd. is an African leguminous multipurpose tree species belonging to subfamily Mimosoideae, subgenus Acacia, highly valued for pods, leaves and gum production. This study estimated the genetic diversity within and among Moroccans populations of the species in the Agdz, N’Koub, Tazarine, Mceissi, Tata, Tissint, Foum Zguid, Gluemim, Msceid and Assa provenances based on 9 quantitative traits which included; Pod Length (LP) (cm), Pod Width (WP) (mm), Pod Weight (WtP) (g), Seed Weight per Pod (WtS P-1) (g), Empty Pod Weight (WtEpP) (g), Seed Number per Pod (SN P-1), Infected Seed Number per Pod (InSN P-1) and 100-seed weight (100-Wt) (g) and shapes of pods throughout two seasons. In the both seasons provenances N’Koub, Tazarine and Tissint present the best means for the majority of traits studied, indicating geographical structuring of the genetic variability but it remained much reduced. Analysis of traits in various forms has shown that purely morphological criteria are inadequate for the selection of the Acacia raddiana trees which had a range of quantitative characters. The various traits are not regularly correlated with pods quality; they appear strictly in a variety of combinations and relations with environmental conditions. In view of this, any attempt for selection based on morpho-metrics traits of the polymorphic species must fail.

Black pod and Canker caused by Phytopthora palmivora and Phytophthora megakarya and Cocoa Swollen Shoot Virus Disease (CSSVD) caused by cocoa swollen shoot virus are important diseases of cocoa in Ghana. Host plant resistance has been considered the most effective method of controlling these diseases. This study was initiated to determine whether multiple forms of resistance to these diseases could be identified in hybrids of cocoa. Thirty six crosses of 6x6 diallel mating design of cocoa were screened for resistance to black pod (P. palmivora and P. megakarya), CSSVD (severe New Juaben CSSV Strain 1A and Nsaba CSSV strain) and Phytophthora canker (P. palmivora and P. megakarya) under a controlled environment. Of the thirty six crosses, 12, 6 and 7 were resistant to black pod, cocoa swollen shoot virus disease and Phytophthora canker, respectively. No cross was found to have combined resistance to the three diseases. This indicates that selection and breeding of cocoa genotypes for multiple disease resistance based on phenotypic data alone could be difficult. Marker assisted selection using tightly linked gene-specific molecular markers will play a larger role in future studies and could be an asset in working with quantitative resistance systems. Cocoa hybrids Alpha B36xPa7/808, Pa7/808xPound 7 and Alpha B36xT65/326 which possess high levels of resistance to more than one disease were identified through this study and would be useful in cocoa multiple disease resistance breeding programmes.

The study was designed to characterize the genetic diversity in a set of rice genotypes with different adaptation to saline soil using microsatellite markers (SSR markers). For this analysis a total of 50 SSR primers across the 12 chromosomes were taken up out of these 50 primers, 37 primers were polymorphic. The average number of alleles per locus was 5.69, indicating greater magnitude of diversity among the plant materials. The average PIC value 0.732 conformed the markers used were highly informative. The cluster analysis grouped the 27 genotypes into nine clusters. Cluster I consisted of nine varieties and all are indica type. Cluster II consisted of three varieties all are salt tolerance. Cluster III consisted of two rice varieties these are tolerant to drought. Cluster IV consisted of seven varieties, which are high yielding varieties. Cluster V consisted of CR1009, which is high yielding variety. Cluster VI consisted of Pokkali and CSR23 both are highly tolerant to salinity. Cluster VII, VIII and IX are mono-clusters consisted of CSR27, CSR10 and Jeeragasamba. The maximum similarity value of 0.786 was observed between the varieties of IR36 and IR64 indicated that these were more closely related. The minimum similarity value of 0.237 was observed between the genotypes IR36 and CSR10 indicated that these two varieties were highly divergent. The varieties possessing high genetic distance value could be utilized for the development of high yielding varieties than the highly closed varieties.

Variability in crop traits creates options for breeders to develop improved cultivars. Many landraces of long cayenne pepper exist in Nigeria but none is recommended for cultivation. Collection, screening and conservation of landraces are therefore vital for the crop improvement. An experiment was carried out at the National Horticultural Research Institute, Ibadan, Nigeria, Latitude 7°22' N Longitude 3°58' E from April 2008 to March 2009 to investigate the extent of variation in reproductive pattern, reproduce-ability and morphology of flowers, fruits and seeds so as to determine markers suitable for pepper improvement. Seeds of long cayenne pepper collected from 25 locations in Southwestern Nigeria were extracted from the fruits, air-dried, bulked and packaged as accession from each location. Six week old seedlings of the pepper were transplanted into 3.6x2.4 m seed beds that were 1 m apart. The plants were spaced 60x60 cm. Plants of the first trial were rainfed; and of the second, were irrigated twice a week when rain stopped. Observations were on flower, fruit and seed traits. Data collected were subjected to analysis of variance combined, across the two trials and means significant were separated by Least Significant Difference. A wide diversity existed within the pepper species on flowering and fruiting pattern. Fruit wall thickness and pedicel length were suggested as morphological markers, number of fruit/plant and seed/fruit; not 1000-seed weight were suitable as markers to select variants for pepper improvement. Any of fruit length, fruit width and days to flowering and fruiting was efficient only when employed together with other markers. Time of cultivation had significant effect on days to first and 50% flowering and fruiting, fruit pedicel length, fruit/plant and fruit weight/plant; but not on fruit length, width and fruit wall thickness; number of seed/plant and 1000 seed weight.

Cultivar discrimination of parental inbred lines is essential for genetic purity of F1 hybrid seed products. It is also essential for the purpose of maintenance of agronomic performance, variety registration, issuance of breeders’ rights, proper labeling of seed products and protection of investments in plant breeding. Digital imaging analysis had been identified as a fast and reliable method for variety discrimination and was applied in this study. With the aid of a digital imaging software (Veho™), 10 seed morpho-metric traits were digitally measured and/or calculated from captured images of 17 inbred lines drawn from the Striga-resistant tropical maize population. The seed metric data were subjected to Pearson’s correlation analysis, the Principal Component Analysis (PCA) and the Single Linkage Cluster Analysis (SLCA). All the parameters showed positive correlation except embryo angle, seed shape factor and circularity index. Seed area, length, perimeter and flatness index contributed the largest variability within the population (eigenvectors = 0.332, 0.328, 0.323 and 0.318), respectively, suggesting their potential usage for cultivar discrimination by digital imaging of maize seeds. Dendrogram constructed from the SLCA showed four major clusters of the inbred population. The clusters constitute a classification tool for future evaluation of genetic purity of test inbred and F1 hybrid samples within Striga resistant maize population. Results of this study demonstrated applicability of digital imaging for analysis of seed genetic quality and will ultimately improve the hybrid seed sector in Nigeria.

Combining ability for maturity traits was studied in pearl millet. Ten parents selected through a field screening technique for their different response to supra-optimal temperature tolerance were crossed in a diallel manner. Forty-five F1 hybrids along with their 10 parents were tested for their performance under supra-optimal temperature exposure at seedling stage with an objective to understand the nature of gene action and to identify parents for breeding programme. The experiment was conducted in three different environments created through different dates of sowing from May to July. The Griffings method of diallel analysis was used to obtain the genetic estimates. Variances due to general combining ability and specific combining ability for all the characters studied, viz., Seedling Thermo-tolerance Index (STI), Seed to Seedling Thermo-tolerance Index (SSTI), panicle emergence, effective tillers, plant height, ear length, ear weight, dry fodder yield, grain yield/plant and total biological yield/plant were highly significant in all the three environments (two stress and one normal) and on pooled basis indicating the importance of both additive and non-additive gene actions. The genotype CVJ-2-5-3-1-3 was identified as the best general combiner for STI as well as maturity traits, while, the genotype (77/371xBSECT CP-1) exhibited highest GCA effects for SSTI in both the stress environments. The genotype (77/371xBSECT CP-1) had high GCA effects for STI and SSTI as well as panicle emergence for earliness. Broad sense heritability (h2bs) was quite high for all the characters studied. However, the estimates of additive genetic variance and narrow sense heritability for STI and SSTI also indicated good chances of effective selection. Preponderance of non-additive (dominance component) was recorded for all the characters suggested the success of hybrid breeding by making use of the expected heterosis. Heat tolerance indices STI and SSTI were not showing any perceptible correlation with either of the maturity traits suggested that pearl millet has great resilience and recovery after stress period during seedling stage.

The present study was conducted to evaluate 45 hybrid rice along with currently available six semi-dwarf, early to mid-early duration and high yielding indicas (Govind, Manhar, Pant Dhan 4, Sarjoo 52, Pant Dhan 12 and Narendra 359) along with four tropical japonicas cultivars (BSI10, BSI16, B4116 and B4122) having wide compatibility gene(s), in relation to analyze gene action and heterosis for grain yield and associated traits. The experiment was conducted in randomized complete design and data collected on various traits were analyzed for heterosis and combining ability. Both additive and non-additive gene action were found to control the expression of all characters. The ratio of General Combining Ability (GCA) to Specific Combining Ability (SCA) variances exhibited greater relevance of non-additive gene action governing yield and its associated traits. Parent B4122 and Sarjoo 52 were found to be the best general combiner for maximum characters, including grain yield plant-1. The crosses B4116xSarjoo 52, BSI10xPant Dhan 12, BSI10xNarendra 359, B4122xManhar and B4122xGovind recorded the highest SCA effects for yield plant-1. Heterosis over mid-parent, better parent and standard variety ranged between -54.17 to 169.70, -58.31 to 150.32 and -64.55 to 146.15%, respectively. The trends of magnitude of heterosis for grain yield and plant height were I/J>I/I>J/J and for days to 50% flowering I/J>J/J> I/I hybrids. The crosses B4116xSarjoo 52, BSI10xPant Dhan 12 and BSI10xNarendra 359 were identified as the best hybrids on the basis of per se performance, high heterosis and combining ability effects. Most of the heterotic cross combinations identified in this study involved indica and tropical japonica lines having wide compatibility gene as their parents. Interspecific hybrids exhibited high heterobeltiosis and economic heterosis.

Introgression lines (IL) from crosses between elite cultivars and wild species are an important resource for mapping quantitative trait loci (QTLs) for yield. In this study, 25 KMR3-O. rufipogon ILs, from an advanced back cross population, were selected for high grain yield in field trials and characterized in detail for yield and related traits from seed to seed. The aim was to dissect the basis of high yield in the entire life cycle to identify common features in high yielding ILs. This study indicated that each IL has a different strategy or a combination of different yield traits to attain high yield. High yield in these ILs was associated with early flowering, high number of tillers, panicles, grains, seed weight per panicle and seed density. Seed germination rate, leaf SPAD chlorophyll meter value, plant height, panicle length and 100 seed weight did not have much impact on yield. Highest significant positive correlation was observed between number of tillers and number of productive tillers (0.98) as expected. A highest significant negative correlation was observed between seed density and seed compactness (-0.95). The new negative correlation between seed germination rate and leaf SPAD chlorophyll meter value in the top 10 ILs was supported by a non significant negative correlation (-0.17) in BC3F4 IL population and deserves further study. Restricting to a specific ideotype in selection may be counterproductive in rice breeding. These ILs are being used in rice improvement and to identify favorable genes from O. rufipogon for increasing yield.

The choice of an efficient breeding procedure depends to a large extent on knowledge of the genetic system controlling the character to be selected. To obtain information on the nature of gene action in West African okra, six generations of parents, first and second filial generations, back crosses 1 and 2 (P1, P2, F1, F2, BC1 and BC2) derived using Generation Mean Analysis (GMA) from crosses involving fourteen selected genotypes were evaluated. The experiments were conducted at the Teaching and Research farm of the University of Agriculture, Abeokuta (7°29N, 3°30E) during the growing seasons of 2008 and 2009. The data suggest that genes influencing some of the characters are dispersed among the parental lines and those interactions are predominantly of the duplicate kind. Additive gene effects were higher than dominance gene effects for most of the traits that were evaluated. Seed yield per plant for cross NGAE-96-0062-2 X CEN 015 was controlled by complementary gene action. Days to flowering, number of pods per plant, number of seeds per pod, matured plant height and seed weight per plant for the NGAE-96-0063 X CEN 015 cross was controlled by duplicate epistatic gene actions. The presence of significant amount of all types of gene action, additive, dominance and epistasis for most of the traits has indicated that methods designed to utilize all of them such as recurrent selection and reciprocal recurrent selection has to be adopted in the breeding programme.

The Nigerian vegetable cowpea accessions differ in phenology with respect to their reactions to day-length. Some are Day Neutral (DN) while others are Short Day (SD) plants. Field experiments were therefore carried out to investigate possible influence of maternal effects on the inheritance of flowering time in cowpea. The distribution of the progenies with respect to days to flowering showed combine effect of both maternal and nuclear influence on the inheritance of flowering time in cowpea. The parental lines, F1, F2 and backcross populations differed significantly (p<0.05) in days to flowering and other yield traits assessed. Days to first and 50% flowering for SD accessions were delayed significantly (p<0.05) compared to DN accessions. The result of the principal component analysis revealed that the most effective characters for distinguishing the parents and progenies included days to first and 50% flowering, No. of peduncles plant-1, No. of flowers plant-1, No. of pods plant-1 and grain yield. The scatter plot and cluster means of the first two principal axes grouped the cowpea accessions into two main clusters. Cluster I comprised of early flowering (<45 days) DN cowpea accessions that were relatively poor in the yield traits assessed. Conversely, the cowpea accessions in cluster II were late flowering (>45 days) SD but prolific in grain and other yield attributes. The hybrids arising from these two groups of cowpea flowered irrespective of day-length, implying continuous podding and all-year-round harvest.

Female telfairia produce succulent and fleshy leafy vegetables with higher nutritional values than male type and therefore preferred at groceries. There is difficulty in identifying this female telfairia at seed and seedling stages. This research identified effect of seed position and fruit origin on the vigor performance and sex ratio of Telfairia occidentalis. Three seed positions of anterior, middle and posterior sections of fruits sourced from four origins of growth were studied in the nursery and field plots at the teaching and research farm of Ladoke Akintola University of Technology, Ogbomoso, Nigeria. Vigor index and percentage emergence were highest for seedlings from the anterior portions with fruits sourced from Imo and Ibadan origins. Genotypic Coefficient of Variation (GCV) and Heritability estimate in the broad sense (HB) for branching, foliage, vine length and diameter traits were also high for plants developed from anterior seed positions and therefore can be reliably selected. More female plants were sighted to have developed from the anterior positions with 3:1 and 2:1 female to male proportions for fruits sourced from Imo and Ogbomoso origins. There were difficulties in obtaining exact genetic sex ratios. This is attributed to differences in flowering time in the male and female plants. Fruits sourced from humid environment of Imo state and seeds extracted from anterior position, recorded highest seedling vigor performance and high female to male proportions for the field established plants. These findings affirm the postulation that more female plants develop from anterior seed positions if sourced from humid agro-ecologies.

The precarious and worsening climatic and weather conditions being experienced in the globe today poses a threat to food security. Thus, there is a need for an urgent search for crops with intrinsic capacity to withstand the stressors and still perform well productivity-wise. The present study focused on the estimation of genetic variability and heritability of morphological traits in four cowpea landraces-akidi, olaudi, ileje ajaka and ileje with the aim of improvement. Seeds of the landraces were obtained from dealers in Enugu and Kogi States, Nigeria, respectively and sown on a plot of land measuring 10x10 meters at the University of Calabar Experimental Farm, Calabar during 2010-2011 growing season. A randomized complete block design was adopted during the planting. Variance estimates, genetic advance and heritability of yield and yield-related traits were estimated. The mean morphological and yield performance showed that there were significant differences (p<0.05) in all the parameters studied except days to 50% seedling emergence with “olaudi” variety maturing fast and having the highest seed yield. The results present high and wide genetic variability in the vein length per plant, number of leaves per plant, leaf area, number of flowers per plant, days to 50% maturity and seed yield. Genetic advance were considerably low but with high heritability estimates in all the traits investigated. The results explicitly revealed that there are sufficient genetic variations to encourage the improvement of these orphan crops.

Physical dimensions of nine morphologically distinct sesame seeds were determined in order to access the extent of variability for size. Length, width and thickness of nine accessions of sesame comprising six cultivated and three wild relatives were measured using micrometer. Other parameters were calculated using standard mathematical procedures. Mean seed length ranged from 2.65 to 3.77 mm, mean seed width from 1.49 to 2.84 mm and mean seed thickness from 0.61 to 1.28 mm. Seed geometric diameter varied from 0.81 to 3.91 mm3 while surface area varied from 2.43 to 48.66 mm2. Principal component analysis divided the 11 variables determined into two components which explained 88.96% of the total variation. First component (56.23%) strongly influenced seed geometric diameter, sphericity, thickness, surface area, length-thickness ratio and length. Second component (32.73%) was affected strongly by width-thickness ratio, 1000-seed weight, length-width ratio, seed oil content and width. The dendrogram generated by the un-weighted pair group method using arithmetic averages (UPGMA) cluster analysis grouped the nine accessions into five distinct clusters indicating genetic diversity. This information can be used to design processing and handling machine for sesame seeds and also to plan crosses in order to maximize the expression of heterosis for large seed size.

The objective of this study was to observe pattern of similarity of reaction to Phytophthora palmivora infection among 25 international cocoa genotypes in five laboratory experiments and a field observation at the Cocoa Research Institute of Ghana by hierarchical cluster analyses. The genotypes were clustered into two distinct populations in all the screening methods suggesting of genetic limitations of the cocoa genotypes studied. The hierarchical cluster analyses of all the screening tests sub-clustered the susceptible and resistant clones differently except in field infection where there was some inconsistency. This is indicative of the possibility of using any of the screening methods to observe similarity of reaction of cocoa genotypes to Phytophthora species. The inconsistencies in field infection are suggestive of the environmental factors influencing the genetic base of infection of Phytophthora species in the field. The resistant and susceptible genotypes were distributed among centres of origin and genetic groups showing that resistant and susceptible genotypes were widely dispersed among origins and genetic groups. The shapes of pods of resistant genotypes were made up of calabacillo and cundeamor while that of susceptible clones was Amelonado. The remaining of the clones, classified as moderately resistant were the most distantly related clones.

Nutritional characteristics of QPM genotypes that have been released are limited. A breeding program has been initiated in 2008 in DR-Congo using varieties selected from several agro-ecological regions. The objective of the present study was to establish a nutritional profile including amino acid and carotenoid content of selected QPM from the DR-Congo breeding program. Six Quality Protein Maize (QPM) and seven normal maize varieties were evaluated for agronomic characteristics and disease reaction. The grain amino acid and carotenoid concentrations were evaluated. The impact of QPM diet on chick’s weight was also determined. QPM Longe 5 produced the highest grain yield in several trials in famer’s fields. Lysine content of QPM-SR-SYNTH and QPM Longe 5 showed significant increase of 33 and 37%, respectively, over the other maize varieties. There was a 50% increase in tryptophan in QPM Longe 5 compared to normal maize varieties. More importantly, the two QPM varieties provide proteins with a better amino acid balance than the normal maize varieties. The level of the carotenoids analyzed was significantly higher in the maize MUS-1 variety with yellow endosperm compared to all the genotypes with white endosperm. The total carotenoid content in MUS-1 was over 250 fold compared to QPM and other maize varieties. The use of QPM in poultry resulted in a 50% increase in body weight compared to normal maize over a 9 week-period. A breeding program combining the benefits of QPM and the high level of carotenoid of yellow maize endosperm should produce superior QPM varieties for human and animal nutrition.

Among the various factors limiting rice yield, salinity is one of the oldest and most serious environmental problems in the world. The available rice germplasm has limited variability for salt tolerance. Hence, the study was to develop salt tolerant rice varieties by inducing variability through mutation and selecting high yielding salt tolerant mutants. Variability and correlation studies were conducted to isolate salt tolerant mutants from two rice varieties ADT 43 and ASD 16. Gamma irradiated (10, 20, 25, 30, 40 and 50 kR) salt tolerant mutants were identified in M2 generation. M3 and M4 generations of the mutant population were investigated for correlation among yield and its components which can be utilized for selection. Altered conditions were observed in the mutant population when compared to the unaltered population depending on the dose, genotype and the character pairs. Morphologically stable salt tolerant mutants till M5 were selected based on the characters identified using correlation studies and for increased yield. Seed yield of mutant lines showed an increase upto 446.94 (20 kR of ADT 43) which was higher than the parental varieties (255.56 and 384.13 for ADT 43 and ASD 16). The number of tillers, panicle length and plant height were also much higher in some mutants than in parent varieties. Results on yield and contributing characters possesses sufficiently high values of heritability and genetic advance which can be utilized for further improvement in rice and in evolving a high yielding saline tolerant variety.

To comparing barleys with different spike type in terms of yield and substantial yield components under terminal heat stress, 12 spring barley genotypes were tested at two levels of sowing dates i.e., normal (5 Dec) and late sowing (20 Jan) during the years 2005-2007. The crop-physiological status of plants was remarkably affected by terminal heat stress which ultimately reduced grain yield. Optimum Plant Height (PLH) of two types of barleys were about 90 and 80 cm under optimum and heat stress condition, respectively indicating that under heat stress, the genes for reduced height may have increased the portion of assimilate to grain rather than to the stem. Observed difference in yield of 2-row genotypes was primarily caused by heat-induced reduction of S m-2 and GW, instead of reduction of G S-1, whereas in 6-row barleys, G S-1 has higher contribution to grain yield than GW. According to comparing genotypes and using stress indices, genotypes which have higher grain yield in both stress and optimum conditions, such as L6 and L8 were identified as heat-tolerant genotypes.