FACTORS INFLUENCING THE AGRONOMIC PERFORMANCE OF THE ADAPTED YAM MINISETT TECHNIQUE IN NIGERIA – PLANTING DATE AND GENDER OF THE FARMER

SUMMARYThis paper describes the results of 3 year's data from farmers using the Adaptive Yam Minisett Technique (AYMT) to produce seed yams in Nigeria. A total of 30 sites were established each year between 2013 and 2015 in the Idah area (Kogi State) of Nigeria and 58 plots in the Amoke area (Benue State) in 2015. Each site had yam setts (80 to 100 g) untreated and treated with a pesticide ‘dip’ prior to planting and farmers (male and female) were free to select the variety and manage the sites as they wished. In line with previous research, the results suggest that treatment does increase the weight of tubers produced by a sett but not necessarily the number of tubers. Varietal differences were also observed. For the first time, the results suggest that the time of planting does have a significant impact on seed tuber weight, with later planting leading to small tubers. Also, the gender of the farmer had an impact on some of the agronomic variables, with male owners of the site generally producing more and larger tubers per sett planted and sprouted than female owners. Various mechanisms for the latter are discussed in the paper.

An approach to determining optimum tuber planting densities in early potato varieties

SUMMARYThirteen experiments conducted near Tenby, Dyfed, between 1973 and 1980, examined the effects of seed-tuber weight and within-row spacing on tuber yields of seven potato varieties grown for early production. These data have been used in an attempt to develop an approach to the determination of optimum tuber planting densities in early crops which will provide agronomists with logically applicable principles. Tuber planting densities, which maximized the net crop return (ware value minus seed cost), were estimated for eight ratios of seed cost to ware value ranging from 0·25 to 8·0. Optimum tuber planting densities decreased with the use of higher ratios of seed cost: ware value and heavier seed, except for ratios of 0·25 and 0·50 applied to yields of tubers > 25 mm harvested in June. In general, later harvesting together with the use of larger riddle sizes give a lower optimum density with ratios < 2·2·0. Optimum densities for Red Craigs Royal, Ulster Sceptre and Vanessa were higher than for the other varieties.The results provide an illustration of how to approach the problem of selecting tuber planting densities in order to maximize net crop returns in early potato varieties.

Determination of optimum tuber planting density for production of tubers in processing ware grades in the potato variety Record

SUMMARYA series of experiments examining the influences of size and spacing of planted potato tubers (‘seed’ tubers) on tuber yields was conducted at four sites in the UK in 1982–84. A new approach to data analysis was used to estimate the optimum tuber planting density for different ware grades. The optimum density, which maximized returns, decreased with increasing seed tuber weight and ratio of seed-tuber cost to ware value and with lower than average total tuber yields. Changing the required ware grade from 40–65 mm to 40–80 mm had a minimal effect on the optimum tuber planting density.Optimum tuber planting densities were lower than in published recommendations but this disparity appeared to be accounted for by differences in the number of stems produced by each planted tuber. There was some evidence that, with lower seed-tuber weights, the optimum planting density differed with site and that at optimum economic densities small and medium seed tubers outyielded large seed tubers.

The determination and economic analysis of relationships between plant population and yield of main crop potatoes

SUMMARYTwo experiments designed to provide data for the estimation of functional relationships, which may be used to determine economically optimum plant populations and planting patterns in Desire'e potatoes, are described. Functional relationships between the number of main stems per acre and yield per acre were estimated from the results of experiment (i). Experiment (ii) investigated the relationship between stem number per tuber and seed tuber weight. ‘Square root’ functions estimated for seed yield and ware yield from the results of Exp. (i) were used to calculate a total Financial Returns curve. This returns curve, together with the Cobb-Douglas function estimated from the results of Exp. (ii), was used to calculate the stem numbers per acre, which would give maximum returns per acre and economically optimum returns in different cost/price situations.