Sweet potato (Ipomoea batatas) growth and tuber yield as influenced by plant spacing on sandy loam in humid tropical environment

The choice of appropriate plant spacing that gives optimum  density of sweet potato (Ipomoea batatas (L.) Lam) is crucial for its productivity, considering that plant density of cover crops affects above-ground access to sunlight, degree of soil surface cover, and below-ground tuberization. The influence of plant planting and the ensuing plant density on growth and tuber yield of sweet potato in a sandy-loam soil in southern Nigeria was assessed in the 2012 and 2013 growing seasons. The field trials involved five plant spacings namely 90 × 90, 60 × 90, 60 × 60, 30 × 90, and 30 cm × 60 cm; corresponding to plant densities of 1.23, 1.85, 2.78, 3.70 and 5.56 plants m–2, respectively. Data were collected on vine girth, number of leaves, leaf area, tuber weight plant–1 and tuber yield, as well as on weed dry matter. Closer plant spacings resulted in higher number of leaves m–2 and leaf area index (LAI). However, tuber weight plant–1 was highest with the second widest spacing (60 cm × 90 cm) and decreased with spacing. By contrast, tuber yield increased with spacing; the closest spacing (30 cm × 60 cm) gave the highest value (12.95 t ha–1) which, however, was similar to 10.55 t ha–1 due to the second closest spacing (30 cm × 90 cm) which, in turn, was similar to 60 cm × 60 cm (9.55 t ha–1) and 60 cm × 90 cm (8.89 t ha–1). Tuber yield correlated with number of leaves (r = 0.57*) and LAI (r = 0.54*), suggesting that the increases in these growth variables due to denser plant population translated into greater photosynthetic activity and translocation of assimilates to the tubers, which manifested as increased tuber yield. Spacing had no influence on weed dry matter. Sweet potato growers on well-drained sandy loam and similar soils in the humid tropics should consider adopting 60 cm × 90 cm with ‘intercropping’ to maximize space and resource use. Alternatively, they should space sweet potato 30 cm × 90 cm in sole production to achieve the desired density (3.70 plants m–2) for optimizing resource use and tuber yield.Key words: leaf area index, number of leaves, tuber weight per plant, optimum tuber yield, sweet potat

Diversity and spatial distribution of epiphytic flora associated with four tree species of partially disturbed ecosystem in tropical rainforest zone

As components of forest communities, epiphytes influence litter and nutrient cycling while providing shelter, nesting materials and food for arboreal animals, thereby promoting diversity. Their preference for certain tree species (phorophytes) influences biodiversity and distribution, but this association is poorly understood in the tropics. We assessed the diversity and spatial distribution of epiphytes associated with four phorophytes (Alstonia booneii, Peltophorum pterocarpum, Mangifera indica and Terminalia catappa) in southern Nigeria, with number of trees sampled as 4, 29, 32 and 44, respectively. The epiphytes were delineated, sampled and identified. Soil samples were collected from tree pockets for textural and pH analyses. On the four phorophytes, 265 epiphytes under seven species (Platycerium elephantotis, Microgamma owariensis, Nephrolepis biserrata, Funaria hygrometrica, Axonopus compressus, Commelina benghalensis and Ficus spp.) and five families (Polypoidaceae, Funariaceae, Poaceae, Commelinaceae and Moraceae) were recorded. The three most abundant were Funaria hygrometrica (109), Platycerium elephantotis (102) and Microgamma owariensis (44), being present on all four phorophytes. Funaria hygrometrica and Platycerium elephantotis were the most abundant on M. indica (32 each) and T. catappa (44 and 39, respectively). Nephrolepis biserrata appeared only once on T. catappa; so too did Axonopus compressus and Commelina benghalensis on P. pterocarpum. Altogether, A. booneii, P. pterocarpum, M. indica and T. catappa had 11, 62, 89 and 103 epiphytes, respectively. Funaria hygrometrica traversed three tree strata, while others were restricted to two or even one stratum. Canopy layer, middle stratum and lower portion hosted four, five and three epiphytic species, respectively out of the seven recorded, pointing to the relative importance of light, spaciousness and moisture, respectively in epiphyte abundance on trees. Epiphytes distribution on phorophytes was not influenced by texture of the arboreal soils, but was inversely related to their pH. This study has provided useful information on epiphyte-phorophyte association in tropical environments and deserves repetition with more tree species in more natural forests.Keywords: forest tree species, tree spatial strata, epiphyte distribution, species abundance, Nigeri

Short-term response of Soil Physical properties of an Ultisol, and Nutrient composition of Fluted Pumpkin to Organic and Inorganic Fertilizer mixtures.

A field experiment was conducted at the Research Farm of Federal College of Agriculture, Ishiagu, Ebonyi State  to evaluate the influence of sole organo-minerals and inorganic fertilizer and mixed forms on some selected soil physical properties and leaf nutrient composition of fluted pumpkin (Telfairia Occidentalis Hook F). The treatments (T1 = Control; T2 = 10 t/ha of rice-husk dust; T3 = 10 t/ha rice husk ash; T4 = 10 t/ha poultry droppings; T5 = 0.375 t/ha of NPK fertilizer 15:15:15; T6 = 5 t/ha of rice husk dust + 5 t/ha of poultry dropping; T7 = 5 t/ha of rice husk dust + 0.188 t/ha NPK 15: 15: 15; T8 = 5 t/ha poultry dropping + 5 t/ha of rice husk ash; T9 = 5 t/ha rice husk ash + 0.38 t/ha of NPK 15:15:15) were built into a randomized complete block design (RCBD) with three replications. Data on soil physical properties and leaf nutrient composition of fluted pumpkin`     were collected and subjected to statistical analysis using Genstat 3 7.2 Edition. The results obtained showed that soil bulk density was significantly reduced on soils treated with different amendment combinations of organo-minerals and inorganic fertilizer compared to the control which received no application of amendment. The soils total porosity, saturated hydraulic conductivity and moisture content were improved when treated the soil with different amendment combinations compared to the control .More so, the results equally revealed that treatments application did statistically improve the leaf nutrient compositions. Key words: Amendments, Soil physical properties, organo-minerals, nutrient composition, fluted pumpkin

The oil palm (Elaeis guineensis Jacq): nature’s ecological endowment to eastern Nigeria

The paper highlights oil palm as a multipurpose tree crop symbolizing nature’s endowment to the people of South East, Nigeria, and presents available evidence that the center of origin for the palm is within the area. The structure of the natural habitat of the oil palm – the groves, from where several genetic collections have been made for the improvement of the crop worldwide – is described. The oil palm is viewed as closely interwoven with the people providing their requirements in terms of food, medicine and materials for infrastructural development. In a wider context, the ecological, socio-economic, and socio-cultural and traditional values of the palm are discussed. The history of efforts to exploit the potentials of the crop through domestication and genetic improvement is given. Because the potential of oil palm is yet exhausted, the action plan for further development in the natural habitat and plantations is also given, highlighting the prospects of increased oil palm production as well as some of the constraints on the way to realising this all-important project. The paper identifies areas needing action research towards the sustainable development of oil palm. Among other suggestions in this direction, the paper recommends the creation of a center of excellence in oil palm studies within the South East, Nigeria to expand the scientific exploitation of the natural groves and encourage plantation establishment for the benefit of not only the people whose God-given gift is now a highly valuable crop in the world, but the entire country and even beyond.Keywords: multipurpose tree, natural groves, oil palm plantations, agricultural growth, South East Nigeri

Agronomic performance and adaptability of three varieties of watermelon (Citrullus lanatus) on sandy loam soil in derived savanna

Amidst tropical vegetables, watermelon (Citrullus lanatus) is increasing popular for its numerous health benefits. In Nigeria, this vegetable crop is still under-produced in the relatively more humid southern part where it is heavily consumed. This situation is partly due to lack of empirical data on existing exotic and local varieties particularly in the southeastern region of the country. In this study, field trials with three watermelon varieties [Lagone (exotic), Koloss (exotic) and Charleston gray (local) serving as control] were conducted on a sandy loam acid soil at Nsukka in southeastern Nigeria typifying Derived Savanna. They were evaluated for agronomic performance including vegetative growth and fruit yield. Koloss took less time (~ 10 days) to emerge compared to Lagone (15 days) and Charleston gray (14 days). Lagone attained first and 50% flowering earlier (36 and 39 days, respectively) than the others. Charleston gray had the longest vine (196.42 cm) nine weeks after planting but showed fewer fruits (3.33) than the others, while Koloss showed largest fruit width (15.66 cm). Fresh fruit yield indicated nominal differences but tended to be highest in Koloss (1.95 kg/plant); Lagone and Charleston gray had 1.85 and 1.74 kg/plant, respectively. For enhanced production of watermelon, Koloss is recommended to farmers in Nsukka agro-environment and similar climate-soil zones in the savanna. In the future, this exotic variety could be hybridized with the local Charleston gray and the hybrid seeds evaluated against the pure lines.Keywords: watermelon ecology, exotic varieties, vegetative growth, fruit yiel

Mineralization rate constants, half-lives and effects of two organic amendments on maize yield and carbon-nitrogen status of loamy ultisol in Southeastern Nigeria

Mineralization rate constants and half-lives of cattle dung (CD) and swine wastes (SW) and their effects on soil organic Carbon (SOC), Nitrogen (STN) and maize yield were evaluated for two years. The study was conducted on a deep, coarse-textured, porous and brownish red soil in Nsukka, southeastern Nigeria. Each of CD and SW was applied at four rates (0, 10, 20 and 40 t ha-1) in a split-plot design as main plot and sub-plot treatments, respectively. The organic materials were only added the first year and residual effect evaluated the second year. The results showed that SW had less C and more N than CD. Also the C/N ratio of CD (5:1) was higher than SW (3:1). Sole SW had higher mineralization rate constants and lower half lives than sole CD but their combined application enhanced both parameters. Mineralization rate constants also increased with increasing rate of application while the half-lives decreased. The CD increased SOC in both years while SW increased SOC and STN in the first year and only SOC in the second year. In addition, C and N contents of the organic materials contributed 45% and 40% changes in SOC and STN, respectively at the end of first year cultivation. In the second year, only SOC was affected by the C content of the organic material thus contributing 28% of changes in SOC. Both C and N contributed 85% changes in grain yield of first season maize with N contributing 69% improvement. In the second year, N alone contributed 56% of the change in grain yield. So SW had less half-lives than CD depicting faster decomposition and release of plant nutrients. There were significant interactions of CD and SW on SOC, STN and maize grain yield.Keywords: cattle dung, swine waste, mineralization rate constants, soil organic carbon, maize yiel