The physical and water absorption characteristics of paddy and brown rice from some early maturing Oryza sativa varieties and newly developed interspecific (O. sativa × Oryza glaberrima) rice varieties were studied. The physical dimensions (length, breadth and width, length/ width ratio, equivalent diameter), grain surface area and volume, sphericity, 1,000-kernel weight, bulk and true densities as well as porosity were determined. A nonlinear moisture diffusion equation was used to model the water absorption curves of the rice varieties at 30-60°C. Digital images of the rice grains were analyzed for their tristimulus color parameters (L*, a*, b*). The physical characteristics of the rice varieties differed significantly (p<0.05). The rice grains were of medium size with length/width ratio ranging between 2.80 and 3.50. Notably, the New Rice for Africa variety WAB 450 aka NERICA 1 had the smallest 1,000-kernel weight and the highest husk/paddy weight ratio. The equilibrium moisture content was significantly influenced (p<0.01) by the soaking temperature and the rice component being soaked. The hydration rate curves were generally characterized by two falling rate periods. The predicted water absorption curves were very close to experimental curves (0.91

Erratic rainfall distribution pattern poses serious challenge to food production in the rainforest transitory zone of Nigeria. Low input technology through the adoption of drought tolerant varieties (NERICA) and the application of Arbuscular Mycorrhiza Fungi (AMF) inoculum could be an alternative option for double cropping of upland rice. Field trials were conducted in the Teaching and Research Farm of the Federal University of Agriculture, Abeokuta in the early and late cropping season of 2012 in the transitory rainforest agro-ecology of Nigeria. The objective was to investigate the performance of some selected upland NERICA rice to the application of AMF inoculum. A 6 x 2 factorial experiment was conducted; six upland rice varieties selected with and without the application of AMF, laid out in split plot arrangement, with AMF in the main block, while variety was in the sub-plot. Each treatment was replicated three times. In both seasons, significant (P < 0.05) effect of AMF inoculation was observed on vegetative, reproductive growth and development parameters in the order + AMF > -AMF. In the early season there was no significant (P > 0.05) varietal variability on grain yield/ha. Conversely, in late season NERICA 4 recorded significantly (P < 0.05) higher grain yield (1050kg/ha) as suggested in significantly (P < 0.05) higher panicle/m 2 (59.50). Performance of NERICA 4 was significantly increased by application of AMF inoculation in the late cropping season.

This study characterized poultry manure extract (tea) and investigated the effects of integrated use of tea and the sequence of phosphorus (P) application [P added before (PBT), after (TBP), or jointly (PT) with tea] on P-sorption characteristics on acidic, alkaline, and neutral tropical soils. Results indicated that diluted tea contained 400 mg nitrogen, 155.80 mg potassium, and 10.48 mg P L −1 and the nutrients were greatest after 2 weeks. Soil P sorption conformed to the Freundlich model, indicating that soil P affinity was less than the aqueous solution at low solution P concentration. Freundlich index (k) in neutral soil was 78 and 94% greater than in acidic and alkaline soils, respectively. The lowest P sorption efficiency and greatest phosphate requirement were in acidic soil. Poultry manure tea could enhance P availability and reduce P fixation irrespective of the sequence of application of tea and P.

The present investigation tested the hypothesis that there would be variation in physiological responses to water deficit among rice varieties from different production ecologies, with contrasting tolerance to water deficit under repeated cycle of soil moisture deficit, at reproductive growth stage. A screen house and a field trial were conducted at International Institute of Tropical Agriculture, Ibadan and Ikenne (Latitude 6° 52' N, Longitude 3° 43' E) respectively. Both experiments had rice varieties (‘IR 64’, ‘WAB 56-104’, ‘IR 77298-1-2-B-10’ and ‘NERICA 4’) and stress status (stress and control) as treatment factor’s, arranged in a randomised complete block design with three replicates. In both trials, the physiological mechanism that underpins varietal differences with repeated cycles of water deficit at the reproductive growth stage was more balanced water status, improved foliar characters, efficient photosynthetic capacity and higher grain yield in comparatively drought tolerant upland rice varieties (‘NERICA 4’ and ‘WAB 56-104’), as opposed with the results for the drought susceptible cultivar ‘IR 64’. A converse pattern was observed on water stressed rice, despite fewer cycles of water deficit on the field. The results could have suggested that the initiation of water deficit is the rate limiting step rather than its intensity at the reproductive growth stage.

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