Phosphorus (P) is expensive to the sub-Saharan African resource-poor farmers; therefore, there is a need for investigation of locally available alternative P sources to enhance farmers' productivity. Optimum P rate was determined during the early and late rains of 1999. Using the optimum P rate, influences of three P sources ogun rock phosphate (ORP), sokoto rock phosphate (SRP), single super phosphate (SSP) and a control were evaluated on amaranth varieties in 2000 at the vegetable research plots of the National Horticultural Research Institute (NIHORT), Ibadan, Nigeria. In 1999, three grain amaranth varieties (NH84/452, NH84/445, and NH84/493) were combined factorially with four P rates: 0, 30, 60, and 90 kgP/ha. Application of P significantly increased plant height, number of branches, leaf dry weight, and grain yield (GY) per plant. Significant increase in GY was in the order NH/493 . NH/445 . NH/452. Optimum P rates across varieties for leaf dry-matter yield was established at 51.8 kgP/ha and for grain yield production was 48.4 kgP/ha. The experiment in the following year, 2000, was a RCB design using the optimum P determined in 1999. Three P sources (ORP, SRP, SSP) and a control were factorially combined with the three amaranth varieties. In the 2000 experiment, grain yield was 21.3, 16.9, 16.0, and 7.8 g/plant, respectively, for SSP, SRP, ORP, and the control. Growth was ranked in the order SSP . ORP . SRP . control. It was concluded for fertilizer recommendation Downloaded by [University of Western Ontario] at 07:52 04 February 2015 purposes that 50 kgP/ha is optimum for grain amaranth production and that amaranth productivity indices could be alternatively improved with indigenous P sources.

Dietary intake of vegetables is low in Sub-Sahara Africa (SSA) compared to the world's average. This situation is worsened by low water availability for vegetable production especially in the dry season. However, amaranth which can be grown in the different agro-ecologies of Nigeria is a dual purpose crop with edible leaves and seeds rich in essential nutrients, minerals and proteins. The crop is also a drought tolerant C4 plant which has the ability to survive under minimum soil moisture condition, hence the reason for its use in the study. This investigation was therefore conducted to discover the optimum water requirements in a screen house, and evaluation of different moisture stress based on the derived optima in two subsequent field trials. In the screen house and field, water stress treatments varied from: -6.0, -1.2 to -0.3 bar (the control). Results in the screen house study showed that optimum soil water potential for amaranth was reached at -1.2 bar, and that variety NH84/493 performed better than the others, in all growth and yield parameters measured. In field trials, bringing the moisture content from dry (-6.0 bar) to -1.5 bar optimum soil water potential favored seedling emergence better than all other treatment combinations. However, treatment combination -0.3, -1.5 bar when the soil was initially wet (-0.3 bar) then bringing it to the optimum (-1.5 bar) gave the best seedling establishment and productivity. Variety NH84/493 grown at -0.3, -1.5 bar performed better than all other interactions. We therefore recommend -1.5 bar and variety NH84/493 amaranth for the SSA vegetable industry, especially for improving dry season productivity.

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract