There is paucity of information on the effect of time of planting on sweetpotato in South-East Nigeria and hence the need for this study; where four planting dates were assessed under field conditions for their comparative effects on growth, carotene, and root yield of orange-fleshed sweetpotato varieties at the National Root Crops Research Institute, Umudike, Nigeria in 2013 and 2014 cropping seasons. The experiment was a split-plot laid out in randomized complete block design with three replications. The main plot treatments were three sweetpotato varieties (Umuspo 1, Umuspo 3, and Ex-Igbariam), while the sub-plot treatments were four planting dates (April, May, June, and July). Results indicated that delayed planting from April to other planting dates significantly reduced orange-fleshed sweetpotato fresh shoot biomass and dry matter. Similarly, planting in April, 2013 produced significantly (p<0.05) higher storage root yield than planting later in May, June, and July by 75%, 92%, and 149%, respectively. In contrast, delayed planting up to June produced a carotene yield of 1267.7µg/g, which was higher than those of April and May by 180% and 82%, respectively. On average, Umuspo 1 produced significantly greater biomass of shoot and root. In 2013, Umuspo 1 also produced higher storage root yield than Umuspo 3 and Ex-Igbariam by 61% and 46%, respectively. However, Umuspo 3 produced significantly highest carotene yield (1918.0µg/g), followed by Umuspo 1 (582.0µg/g), while Ex-Igbariam had the lowest value (296.5µg/g). There were no significant interaction effects on root yield in both years, but there was a significant interaction on carotene yield, which was highest in Umuspo 3 in July, followed by the June planting date. For high fresh shoot and storage root yields, planting Umuspo 1 in April is recommended, while for high carotene yield, planting Umuspo 3 in June or July is recommended.

Despite the importance of Allanblackia floribunda as a multipurpose tree grown in south east Nigeria, where small scale farmers retain some trees on their farm land for soil rejuvenation, there is a dearth of research information on intercropping the tree species with grain crops in the region. Field experiments were conducted in 2016 and 2017 cropping seasons in south eastern Nigeria to evaluate the effect of 2–3 years old Allanblackia floribunda alley systems on soil chemical properties and growth and yield of maize and mungbean. The experimental design was a factorial arranged in a randomized complete block design (RCBD). Standard labouratory procedures were used for the soil chemical properties while data on growth and yield were collected for maize and mungbean. All the data collected in the experiments were subjected to analysis of variance using GenStat Release 12.1. Before the commencement of first year double cropping and after two years of cropping, soil samples were collected from the respective plots and analysed for soil chemical properties. The maize experiment had two maize spatial arrangements grown between the tree alleys and in monocrop plots. After the harvest of maize, mungbean was introduced at two plant spacings of 30 × 20 cm and 20 × 20 cm. Soil phosphorus was significantly increased in Allanblackia tree alley than in the control by 55.6

Field experiment was conducted at National Horticultural Research Institute (NIHORT), Mbato Sub-station, Okigwe, Imo State, South-eastern Nigeria in the 2012 and 2013 cropping seasons to establish the most appropriate time to introduce component crops in cocoyam/cowpea mixture. Five different planting schemes (two and four weeks before, two and four weeks after and same day) and two cowpea genotypes (climbing Akidienu and erect IT97K-499-35) were used. The component crops were grown in monocultures to assess the productivity of the systems. The experimental design used was a completely randomized design with three replicates. Growth and yield of cocoyam and the cowpea genotypes increased significantly (P<0.05) when either of the component crops was planted earlier than the other. Intercropping reduced significantly (P<0.05) cocoyam yield by 0.7 − 74% in IT97K-499-35 and 22 − 80% in Akidienu. Sowing the cowpea genotypes the same day or before cocoyam resulted in over-yielding of cowpea, whereas sowing Akidienu and IT97K-499-35 after cocoyam caused pod yield reductions of 64% − 73% and 32% − 59% on average, respectively. Cocoyam planted two weeks before IT97K-499-35 produced more satisfactory yields of the intercrops than the other planting schedules with LER, LEC and ATER of 2.15, 1.03 and 1.57, respectively.

Intercropping fruit vegetable crops with legumes may influence performance of component crops and improve residual nitrogen contribution to the cropping system. Eggplant (Solanum spp.) genotypes whose fruit and leaves are a good source of income and provide essential vitamins and minerals for good health were intercropped with vegetable Cowpea (Vigna unguiculata Walp ssp. sesquipedalis) in 2 years. Eggplant was monocropped using genotypes ‘Ex-Lantan’, Solanum macrocarpon L., S. melogena L, S. aethiopicum L. (mikky mikky-Gilo), ‘Nsukka green’, and ‘Nsukka white’. A semiprostrate vegetable cowpea was grown in monocrop and the crops were intercropped. Eggplant fruit yield, pod yield of cowpea, and interrelationships between yield characters, as well as the biological and economic productivity of the system, were studied. Intercropping eggplant with cowpea produced a high degree of complementarity. The mono- and intercropped eggplant genotypes exhibited wide genotypic variation. On average over two cropping seasons, ‘Nsukka green’/cowpea intercrop followed by ‘Nsukka white’/cowpea intercrop had the highest total land equivalent ratio (LER; 1.78) and land equivalent coefficient (0.79) compared to other mixes. The ‘Ex-Lantan’/cowpea intercrop had the highest mean gross monetary and net returns (NR); the S. melogena/cowpea intercrop produced the highest total cost of production (TCP) among intercrops; the highest benefit–cost ratio (BCR) was for monocropped S. macrocarpon. Among intercrops, the BCR of S. macrocarpon/cowpea mix was highest compared to ‘Ex-Lantan’, S. melongena, S. aethiopicum, ‘Nsukka green’, and ‘Nsukka white’, at 0.57%, 21.58%, 33.46%, 26.30%, and 19.89%, respectively. There was a positive but weak linear relationship between LER and NR and between LER and BCR. Intercropping eggplant with cowpea enhances productivity and financial return.

Studies were carried out at NRCRI, Umudike in 2000 and 2001 cropping season to determine the performance of three okra varieties in an okra/sweet potato intercropping system. In 2000, intercropped okra flowered earlier than sole, but both flowered at the same time in 2001, with no significant difference. Intercropping generally increased okra plant height while pod width was significantly (p<0.05) more in NHAe 47-4 than other varieties. Pod length was the same for the three varieties in 2000 but differed in 2001 with NHAe 47-4 longer than other varieties. Interaction of okra, and sweet potato and cropping system showed significant (p<0.05) difference in both pod width and pod length. Intercropping okro with TIS2532.op.1.13 significantly increased number of pods per plant than with other sweet potato varieties.

Among the crops grown in the tropics, sweet potato ranks second after cassava. Field research was conducted at the National Root Crops Research Institute, Umudike, south-eastern Nigeria, to evaluate the response of orange-fleshed sweet potato varieties to intra-row spacing. Treatments included four varieties ( Umuspo 1, Umuspo 3, Ex-Igbariam and Ex-Oyunga ) and three intra – row spacings (20, 30 and 40 cm). Weed density and growth decreased, but sweetpotato leaf area index (LAI), fresh shoot biomass and storage root yield increased significantly (P<0.05) at the closer spacing (20 cm) than at the wider spacings (30 and 40 cm). Umuspo 1 had higher LAI and shoot biomass; and suppressed weeds more than other varieties. Also, storage root yield of Umuspo 1 (27.2t/ha) was significantly higher than that of Umuspo 3, Ex-Igbariam and Ex-Oyunga by 35, 103 and 325%, respectively. Keywords: Plant spacing, variety, yield, orange-fleshed, sweet potato, Nigeria

Improved varieties of both vegetable cowpea (IT92KD-263-4-1) and maize (OBA 98) were grown in mixture at Michael Okpara University of Agriculture, Umudike research farm for two cropping seasons (2006 and 2007) in order to determine the suitable relative sowing time of the component crops. The experiment was laid out in a randomized complete block design and with three replicates. The treatments were vegetable cowpea and maize separately planted in their pure stands, vegetable cowpea and maize simultaneously sown on the same day, vegetable cowpea sown 2, 3, 4 weeks before maize and vegetable cowpea introduced 2, 3 and 4 weeks after maize was sown. Widest leaf area, heaviest total aboveground dry matter and nodules per plant of vegetable cowpea were attributed to the vegetable cowpea sown 4 weeks before maize. Similarly, maize leaf area index, aboveground dry matter, number of grains per cob, 100-seed weight and grain yield per hectare were highest when maize was sown 4 weeks before introducing vegetable cowpea. The highest LER of 1.61 and 1.58 in 2006 and 2007, respectively were attributed to the vegetable cowpea sown 4 weeks after maize. It was therefore, recommended that the resource poor rural farmers should introduce the vegetable cowpea 4 weeks after sowing the maize seeds since they usually target the combined yield from the component crops of the farmland

Field experiment was conducted during 2013 and 2014 cropping season at Umudike, southeastern Nigeria, to evaluate the effect of fertilizer combinations (poultry manure, NPK (15:15:15) and agrolyser) on two varieties of orange-fleshed sweetpotato (Ipomoea batatas). The experiment was a split-plot laid out in randomized complete block design (RCBD) with three replications. Combined application of 2.5 t/ha poultry manure + 200 kg NPK produced significantly higher leaf area index of 3.3, shoot biomass of 31.9 t/ha and multiplication ratio of 1:48than the control or application of NPK or agrolyser alone. Application of 2.5 t/ha poultry manure + 200 kg NPK also produced significantly higher average storage root yield of 29.1 t/ha than no fertilizer or agrolyser application, and also gave higher carotenoid level than application of NPK or the control. Umuspo 1 suppressed weeds more and significantly produced 598% higher shoot biomass and 125% higher average storage root yield than Umuspo 3. Umuspo 3 variety however, had a carotenoid level of 2268.1mg/g, which was higher than that of Umuspo 1 by 1860%. The highest net monetary returns from the cultivars accrued from a combined application of 2.5t/ha poultry manure and 200 kg NPK while the lowest return was from where no manure was applied or where agrolyser was applied alone. Keywords : Carotene, fertilizer combinations, orange-fleshed, Ipomoea batatas, yields

Abstract. Cracking irvingia wombulu nut is one of the biggest challenges in its processing which is not yet mechanized. Kernel extraction from the irvingia nut is still being carried out by the use of hammer, stone or matchet to split the nut. This process is injurious, labour intensive, promotes drudgery and results in a lot of kernel breakages. The knowledge of mechanical properties of irvingia wombolu nuts is essential to design cracking device to extract the kernel without much breakage. The effects of moisture content and loading orientation on some mechanical behavior of Irvingia wombolu nuts obtained from Rivers State, Nigeria, was carried out under compressive loading using tensiometer at 28 0 C and speed of 20 mm/min. Four moisture contents (12, 20, 29, and 36% wb) and two orientations (axial and longitudinal) were used for the study. The results showed that compression force, deformation energy and unit volume energy increased with increasing moisture content for both transverse and longitudinal loadings. The effect of moisture content and loading orientations on compression force and deformation energy were statistically significant (P

Thirty-eight high and low cyanide cassava genotypes were evaluated for growth and yield. The experiment was fitted in a randomized complete block design with three replications. Analysis of variance (ANOVA) revealed significant difference (P<0.05) in growth and yield parameters, indicating strong genetic variations among the genotypes. Significant (P<0.05) highest average storage root weight of 1.5 and 1.8 kg were obtained from TMS 94/0035 (high cyanide cassava genotype) and TMS 98/0505 (low cyanide cassava genotype), respectively. Correlation analyses indicated significant (P<0.05) and positive associations between number of storage roots per plant, average storage root weight and root yield in the two types of cassava genotypes tested, indicating that the parameters are good indices that can be improved upon during breeding and selection to enhance root yield. Four high cyanide cassava genotypes (TMS 99/2123, TMS 96/1642, TMS 98/0068 and TMS 94/3200ï´¿ were outstanding in fresh root yield performance. To improve fresh root yield in cassava, the inter-relationships among the various agronomic character of the cassava genotypes demands appropriate attention. The study gives more information on the improvement of fresh storage root yield of cassava. Key words: High cyanide cassava genotypes, low cyanide cassava genotypes, correlations, growth, yield.

The study evaluated the slips of four landraces and five hybrid varieties of white yam for growth and minituber yield in 2011 and 2012 cropping seasons at the National Root Crops Research Institute, Umudike, south east Nigeria. The experiment was laid out in a randomised complete block design with three replications. Landrace Hembamkwase had the longest vine (163.3cm), followed by hybrid TDr 89/02665 while Ame produced the shortest vine. Hembamkwase also out-yielded other genotypes except Ame in 2011 and Nwopoko in 2012. Generally, slips of the hybrid varieties, especially TDr 89/02665 and TDr 97/19177 performed poorly in tuber yield compared to the landraces. Mini-tuber weight showed significant and positive correlation with tuber yield while simple linear regression also showed high coefficient of association between tuber weight and yield. The higher yield associated with the landrace Hembamkwase was attributed to greater slip size, indicating that the landrace can be hybridized and the trait selected for in yam improvement. Keywords : Dioscorea rotundata , yam slips, genotypes, mini-tubers

In the rainforest of south eastern Nigeria, new varieties of orange-fleshed sweet potatoes (Ipomea batatas Lam) have been introduced but appropriate soil nutrient management for these cultivars is lacking. The present study evaluated the response of two varieties of orange-fleshed sweet potatoes (Umuspo 1 and Umuspo 3) to different fertilizer combinations (Poultry manure, NPK and agrolyser). The experiment was a split plot laid out in a randomised complete block design with three replications. Results obtained showed that weed dry matter was lower with the control or with application of 2.5t/ha poultry manure + 200kg NPK than with application of poultry manure at 10t/ha. Storage root yields obtained from 400kg/ha NPK(the check) or 2.5t/ha poultry manure + 200kg NPK were comparable but significantly higher than the yields from the control or agrolyser or from 200kg/ha NPK + agrolyser. Umuspo 1 variety gave higher shoot biomass and lower weed density than Umuspo 3. There was no interaction between the fertilizer combinations and variety, suggesting that the orange-fleshed sweet potato varieties responded similarly to nutrient management strategies.

A motorized ginger rhizomes splitting machine based on sawing principles with serrated blade was developed in recognition of the constraints imposed by the traditional splitting method. Two ginger varieties (UG I and UG II), 3 feed rates (57, 97, 141 kg/hr), 3 blade shaft speeds (280, 310, 380 rpm) and 3 ginger rhizome sizes (large, medium and small) were used to evaluate the performance of motorized ginger rhizomes splitting machine. A 2 x 33 factorial experiment in a completely randomised block design was used to study the effect and interactions of variables on machine capacity (MC), splitting efficiency (SE), percent injured (PI) and percent dust (PD). Result showed that there was a decrease in SE with increasing speed with UG I having higher values than UG II. Percent damage and percent injured increased with increasing speed with UG II having higher values than UG I. Percent injured and splitting efficiency increased with increasing size of ginger rhizomes with UG I having higher values than UG II. The analysis of variance (ANOVA) showed a highly significant effect of variety and size on the splitting efficiency.

The work evaluated the responses of two Amaranthus species to poultry manure, fish effluent, NPK fertiliser and control in randomised complete block design. A. hybridus was taller, thicker and had more leaves per plant than A. viridis. For each Amaranthus variety, poultry manure produced highest number of leaves and tallest plants with thickest stem followed by fish effluent and NPK fertiliser. A. hybridus had higher leaf and marketable yields/ha than A. viridis. Leaf and marketable yields/ha were highest with poultry manure followed by fish effluent and NPK fertiliser. Leaf yield/ha increased by 105, 34 and 34% for poultry manure, fish effluent and NPK fertiliser, respectively compared with the control in A. hybridus and by 284, 132 and 146% in A. viridis. Similarly, marketable yield/ha increased by 116, 45 and 45% for poultry manure, fish effluent and NPK, respectively in A. hybridus and by 176, 16 and 43% in A. viridis over the control.

Field experiments were conducted in 2009 and 2010 to evaluate the response of soya bean to pre-sowing seed inoculation with Rhizobium japonicum strains and liming the soil with different lime materials. The experiments were conducted on sandy loam soils at Calabar in the rainforest and Obubra in the southern guinea savanna zones of Cross River State, Nigeria. Treatments comprised factorial combinations of Rhizobium (with and without inoculation) and liming material (no lime, calcite, gypsum, and dolomite) laid in randomized complete block design replicated thrice. Liming the soil was effective in increasing root nodulation, plant vegetative growth and grain yield in Calabar, but not at Obubra. Pre-sowing seed treatment with Rhizobium japonicum was also more effective in Calabar than at Obubra. Root nodulation, plant height, pod-bearing branches, reproductive node number, dry matter yield, pods/plant and yield of grain were significantly influenced by the combined effect of inoculation and liming, but not the number of seeds and seed weight/pod. Sowing inoculated seeds in calcite- limed soils gave the best results but the difference between gypsum and dolomitic lime was not significant. The grain yield which averaged 2.34 t/ha in the Obubra grown crop was higher by 21.9 % compared to the Calabar grown crop. Differences in the response to seed inoculation and liming were attributed to weather and edaphic factors.

Two years field experiments laid out in randomized complete block design were conducted during the 2006 and 2007 wet seasons in the lowland humid forest zone of south-eastern Nigeria to investigate the productivity of cocoyam / vegetable cowpea intercropping as influenced by spatial arrangement and cowpea growth habit. Cocoyam and vegetable cowpea were each planted in monoculture and intercropped within and between rows. The results showed that corm yields obtained from cocoyam intercropped within the row of climbing Akidienu were significantly higher than the yields when combined within erect IT86F-204-1. The erect IT86F-204-1 gave higher fresh pod yield under sole cropping while the climbing Akidienu gave higher fresh pod yield when intercropped within cocoyam plants. Intercropping did not depress cowpea pod yield except where cocoyam was combined between erect IT86F-204-1 in 2006. Assessment of the productivity of the mixtures using LER, ATER and monetary returns showed yield advantages. The highest LER (2.9), ATER (2.5) and net monetary returns (N491,550) (using mean of two years) were obtained when cocoyam was intercropped within the climbing Akidienu vegetable cowpea rows. Keywords : Productivity, Intercrop and spatial arrangement