The inland valleys (IVs) have the potential of growing three crops in sequence within a year without supplemental irrigation. Considerable opportunity exists for growing the third crop between main crop and dry season cropping. This is a niche that has not been exploited. Field experiments were conducted at the University of Agriculture, Abeokuta, Nigeria in 2000–2003 to determine the growth and yield performance of upland rice (Oryza sativa L.) in lowland rice–upland rice–fallow, lowland rice–upland rice–cowpea [Vigna unguculata (L.) Walp], and lowland rice–upland rice–vegetable sequences in an IV. Lowland rice–upland rice–fallow, lowland rice–upland rice–cowpea, lowland rice–upland rice–okra (Abelmoschus esculentus L.), lowland rice–upland rice–amaranth (Amaranth cruentus), lowland rice–fallow–fallow, lowland rice–fallow–cowpea, lowland rice–fallow–okra, and lowland rice–fallow–amaranth sequences, which ran concurrently constituted a cropping cycle. The first, second, and third crops in all the cropping cycles were planted in May, October and January, respectively. The grain yields of preceding lowland rice in the various sequences with or without upland rice were similar. The preceding lowland rice variety BW 311‐9 enhanced the height and grain yield performance of upland rice. The grain yields of the two upland rice varieties in the existing niche were similar in the three‐crop sequence but substantially lower than the obtainable yield in an upland ecology. Upland rice crop could be grown in between the lowland rice and vegetable/cowpea without reducing the yields of lowland rice and vegetable. Inclusion of upland rice in the sequence decreased the overall benefit/cost ratio of triple cropping. Thus, two‐crop sequence, which is currently being practiced by the traditional farmers, should be adhered to, until a suitable crop or technology is identified.

SUMMARYAlthough triple cropping in inland valleys of Nigeria is technically feasible, the third crop between the main crop and dry season non-rice crop has been considered not to be economically viable because of poor crop establishment due to soil inundation. The identification of an appropriate technology with low input, such as ratooning, would allow this niche to be utilized. Field experiments were conducted at the University of Agriculture, Abeokuta, Nigeria in 2007–2008 and 2008–2009 cropping seasons to evaluate the performance of the main and ratooned crops of lowland NERICA (New Rice for Africa) rice (Oryza sativa L.) varieties in a lowland rice–ratooned rice–fluted pumpkin (Telfairia occidentalis Hook F.) sequence. The experiment was laid out in a randomized complete block design with three replicates. The lowland rice varieties used were NERICA-L 19, NERICA-L 20, NERICA-L 22, NERICA-L 24, OFADA, NERICA-L 26, NERICA-L 41, NERICA-L 42, NERICA-L 44 and NERICA-L 47. The grain yield of the main rice crop ranged from 5.0 to 7.3 t ha−1 in 2007–2008 cropping season and from 4.1 to 9.1 t ha−1 in 2008–2009. The ratooned rice had a grain yield of 1.0–4.7 t ha−1 in 2007–2008 and 1.2–3.4 t ha−1 in 2008–2009. The total grain yield obtained in 2007–2008 from the main and ratooned rice crops in seven months was 6.7–11.6 t ha−1, while in 2008–2009 it was 5.3–2.6 t ha−1. The fresh leaf yield of fluted pumpkin ranged from 14.6 to 16.9 t ha−1 in 2007–2008 and from 18.3 to 19.8 t ha−1 in 2008–2009, similar to previously reported rainy season unfertilized yields. Thus, a ratooned rice crop appears to be a feasible technology capable of boosting rice production and consequently increasing the overall productivity of the inland valley in a rice–rice–vegetable cropping sequence.

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Pre-harvest operations affect the quality of food products. This study evaluated the impact of age at harvest (AH), cropping system (CS) and variety on the chemical and functional properties of high quality cassava flour (HQCF). Two white-fleshed (TMS 30572 and TMS 98/0505) and three yellow-fleshed (TMS 97/JW2, TMS 01/1371 and TMS 01/1368) cassava varieties planted either as sole crop or intercropped with maize were harvested at 12, 15 and 18 months after planting, and processed into HQCF. Chemical composition (proximate, mineral), physico-chemical properties (pH, total titratable acidity and colour) and functional properties (bulk density, water absorption index, dispersibility, swelling power, solubility index and pasting properties) of HQCF were determined. Data obtained were analysed using general linear model (GLM). AH had a significant (P < 0.05) effect on proximate and mineral composition, functional and physico-chemical properties, peak and breakdown viscosities, and peak time of HQCF. CS significantly (P < 0.05) affected the crude fibre, fat, bulk density, swelling power, mineral composition, and physico-chemical properties (except L* and b*) of HQCF. Variety significantly (P < 0.05) affected the proximate (except moisture) and mineral composition, functional properties, and breakdown viscosity of HQCF. The interactive effect of AH, CS and variety was significant (P < 0.05) on fat, dispersibility, mineral composition, and physico-chemical properties. In terms of carbohydrate content, it is desirable to harvest cassava at 12 months after planting, with TMS 98/0505 being the choice variety. Recommendation of the desirable AH, CS and variety will vary according to the desired quality of the end-products. Age at harvest is the most important single factor affecting the proximate composition and functional properties of HQCF.