Assessment of antibody responses to Newcastle disease vaccination in Nigerian indigenous chicken lines selected for sheep red blood cell antigen

This research was carried out to evaluate serum haemagglutination inhibition antibody titres to a Newcastle disease virus vaccine in two Nigerian indigenous chicken lines selected for sheep red blood cell antigens. One hundred Nigerian indigenous chickens were used. These chickens belonged to the fourth generation of flock that had been divergently distinguished into a high antibody titre chicken line (HATC) and a low antibody titre chicken line (LATC). Chicks were given a NDV vaccine at six weeks of age, while blood samples were collected from each chick at seven days post-administration. The antibody titres of chicks were determined through a haemagglutination inhibition test and the data collected were subjected to analysis of variance using SAS 9.2 version. It was found that sex had no significant effect on the antibody titre values (p>0.05), while the genetic line and sex by genetic line interaction had significant effects on the antibody titre values. Female chicks of LATC recorded a significantly lower ND antibody titre (4.21+0.47) compared to HATC females (8.04+2.02). Also, male chicks of LATC recorded a significantly lower ND antibody titre (4.26+1.20) compared to HATC males (7.25+0.48). Meanwhile, there was no significant difference between male and female chicks of LATC as well as between male and female chicks of HATC. Based on the differences observed in ND antibody titres between the genetic lines, emphasis should be placed on policies to develop HATC and LATC along ND resistance. Therefore, we recommend that when considering ND infection which exerts substantial losses to the poultry industry, HATC should be favoured over LATC.

Soil resilience and management of former sugarcane (Saccharum officinarum L.) lands on the Naparima Peneplain, Trinidad and Tobago

The lands of the Naparima Peneplain, Trinidad and Tobago, are an invaluable resource with multiple land use characteristics including agricultural diversification. Sections are classified as Class V soils, non-resilient with minimum recovery over the medium term, and as Class IV soils, slightly resilient with improvements in medium term resulting in significant land management and land use changes. These lands were under sugarcane cultivation for centuries, from the colonial era until the closure of the sugar factory in 2003. Since then, as in so many other Caribbean territories, the land has been ear-marked for agricultural diversification and made available to small farmers for the production of commodities for the domestic market. Land use changes in the post-sugarcane era have resulted in approximately 14,000 hectares becoming available for possible agricultural diversification. However, the positive impact on domestic food supply that was anticipated has not materialized. A land resource study was conducted in 2012–2014 in the La Gloria and Cedar Hill sections of Caroni (1975) Ltd lands on the Naparima Peneplain, to determine the effect of long-term sugarcane (Saccharum officinarum L.) cultivation on land degradation and soil resilience by comparison with data from historical records and to make recommendations on the way forward. Assessment of land use, chemical and physical soil properties, and extent of soil erosion, comprised the study. The most severe land management factor was identified as chronic and widespread soil erosion, especially in Cedar Hill, with additional problems of subsoil exposure, soil slumping and movement. Soil erosion studies (Universal Soil Loss Equation (USLE)) indicate estimates of 35–74 t/ha affecting 75% of the lands. Historical records on soil physical indices such as bulk density, clay percentage in the profile and available water, revealed that these parameters were stable over the period 1977–2014. However, chemical indices, inclusive of organic carbon, nitrogen and pH, reflect significant decline correlated with reduced soil fertility and land abandonment. While identifying stable soil resilience indices is valuable, the immediate problem is the correction of soil erosion, which results in considerable land abandonment. Therefore, it is recommended that the land be restored to an acceptable level of soil fertility, specifically with respect to its organic matter content, and that infrastructural adjustments be made to stop or greatly minimize soil erosion so that these lands could be used to contribute to national food security as envisaged.

Evaluation of yield and other agronomic traits in pepper (Capsicum chinense Jacq.) under open-field conditions in the humid tropics

Sixty-eight pepper (Capsicum chinense Jacq.) accessions were evaluated for yield (measured as total number of fruits per plant and total fruit weight per plant) and 15 other traits under open-field conditions in two trials, one conducted in the dry (Trial-1) and the other in wet season (Trial-2) of 2014. Each trial was set in a randomized complete block design with three replications (20 plants per replicate) at The University of the West Indies Field Station, Mount Hope, Trinidad and Tobago. There were significant differences (p < 0.01 to 0.001) among the accessions for all traits except plant height, plant canopy width in Trial-1, and early vigour in Trial-2. Total number of fruits per plants was weakly correlated (r = 0.37 in Trial-1, r = 0.45 in Trial-2; p < 0.01 to 0.001) with total fruit weight per plant, but was strongly associated with number of fruits per plant in the first and second 5 pickings (r = 0.78 to 0.97, p < 0.001) and moderately negatively correlated (r = -0.33 to -0.56, p < 0.01 to 0.001) with fruit width and average fruit weight. Total fruit weight per plant was positively associated with fruit weight per plant in the first and second 5 pickings (r = 0.66 to 0.89, p < 0.001), and negatively correlated (r = -0.41 to -0.69, p < 0.001) with days to 50% flowering and fruiting. A comparison of linear regression lines showed that the relative ranking of the accessions over seasons did not change for days to 50% flowering and fruiting, fruit weight per plant in the second 5 pickings, total fruit weight per plant and fruit width. The implications of these results are discussed.

Selection of putative relic cacao (Theobroma cacao L.) genotypes in farmers’ fields in Trinidad and Tobago

Trinidad and Tobago is a repository of putative relic cacao genotypes, given its long history of cultivating cacao from the 1700s onwards. As part of a project conducted between 2009 and 2011, funded by the World Bank Development Market Place, World Bank Project TF 093747 (DM 2008), 106 putative, ancient cacao varieties were collected from farms throughout Trinidad and Tobago to be conserved and utilized to preserve traditional quality (flavour) attributes. The objective of this article is to provide information on agronomic and phenotypic traits of 94 of these ‘relic’ accessions collected in farmers’ fields (FA). These are presumed to be relic Criollos or Trinitarios (selected pre-and post-1930s), and were selected over six cocoa production zones in Trinidad and Tobago. In addition, data for 31 regional Trinitario cacao accessions, which are conserved at the International Cocoa Genebank Trinidad (ICGT) were assessed. Morphological assessment of the selections was based on 22 phenotypic traits including characteristics of economic interest, viz. bean number (BN), individual dried bean weight (DBW), total wet bean weight (TWBW) and pod index (PI), which ranged from 26.4 to 58.0 (CV 16.3%); 0.6g to 2.12g (CV 22.6%); 42.5 to 228g (CV 24.2%) and 10 to 57 (CV 27.5%), respectively. Significant differences (p < 0.0001) were found among the production zones for BN and DBW only. Four zones had selections with significantly higher BN and all six had selections with superior TWBW relative to the ICGT clones studied. No association between cotyledon colour and leaf petiole hairiness was found, suggesting independent inheritance of these traits used for preliminary identification of ‘Criollo-like’ genotypes in the field. FAs from Tobago generally had selections with paler cotyledons, implying relatively more pronounced Criollo ancestry. Principal Component (PC) scores 1 and 2 accounted for 74.7% of the phenotypic variation expressed by the accessions studied in terms of five traits, based on Principal Component Analysis (PCA). PI and TWBW were major contributors to PC 1, while for PC 2, the major contributors were BN and DBW. The results of PCA and cluster analyses suggest that a phenotypically diverse and unique selection of genotypes was collected from the farmers’ fields, relative to studied ICGT types, several of which displayed ‘Criollo-like’ and Trinitario characteristics (large, plump seeds/beans with pale cotyledons) and favourable yield potential. These can be utilized to enhance the genepool at the ICGT, for breeding to introgress favourable Trinitario genes into national recurrent breeding programmes and for commercial cultivation.

Successful manipulation of the growth cycle of yam (Dioscorea spp.) for year-round production for food security and climate change

Yams are important items of diet throughout the Caribbean Region and, among them, the cultivars of the species, Dioscorea alata L. and D. esculenta (Lour.) Burkill are particularly important in the Eastern and Southern Caribbean, although the latter is so to a lesser extent. With a growing period of approximately nine months and a corresponding dormancy period, these cultivars are produced on an annual basis like clockwork, providing food yams for approximately three months of the year, the period of availability coinciding with the period of dormancy as the latter marks the natural period of storage of the tuber. Consequently, the breakage of dormancy marks the beginning of the end of natural storage as the emerging sprouts signal the onset of the next growing period. This coincides with the start of the rainy season and the yam is adapted to existing climatic conditions that provide the ideal environment for both plant establishment and tuber growth. Cultivars of the two species bear no reproductive seed and therefore, are completely dependent on vegetative means for perpetuation. Any adverse development during storage or early growth that prevents sprouting or tuber initiation and growth, results in the permanent loss of the affected material and potentially threatens loss of the specific cultivar. Hence, climate change events such as shifts in the onset of the rainy season, extension of the dry period and incidences of severe weather associated with excessive flooding that can result in death of roots and developing tubers, pose real risks to the persistence of the cultivars of D. alata and D. esculenta that are produced in the Caribbean Region. In order to counteract these effects, what is needed is the manipulation of the growth cycle to allow for year-round production so that the changes that have been observed with respect to climatic and weather patterns will not result in a loss of planting material and, by extension, loss of germplasm. It is well-established that the growth cycle is under hormonal control and that the key to year-round production is the breaking of the physiological lock on the growth cycle that is responsible for the seasonal production by which these species are characterized. There have been many attempts by researchers in the past to achieve this, but without success until relatively recently. Most attempts have explored the use of natural and synthetic plant growth regulators. Further, past attempts have focussed on the breakage of natural dormancy and induction of early sprouting, but instead, the success reported here, was achieved by delaying sprouting to beyond the period of natural dormancy in a novel approach that eliminates the use of growth regulators and other chemicals. This paper reports how reduced temperature storage has been used successfully to break the physiologically controlled growth cycle in cultivars of D. alata and D. esculenta, producing yams all year long by delaying the breakage of dormancy, ensuring not only an extension of the availability of yam tubers for food but also availability of viable planting material throughout the year. It was found that tubers can be stored successfully for an entire cycle, so that tubers from the previous year can meet tubers of the current year’s harvest providing a buffer against crop loss from any adverse biotic or climatic event. The effects on sprouting patterns are described. The use of reduced temperature storage for this purpose has not been reported and this account serves to fill an important gap in documented yam dormancy research.