Seedling tests for reaction of tomato cultivars to leaf mould (Cladosporium fulvum) showed that a single race 1·3, or a mixture of races 1 and 3, was present at four sites in the Western State of Nigeria sampled at different times during 1967 and 1968. Vetomold, Vantage, Vinequeen, Astronaut, Floradel, and Tarran were immune and Purdue 135 was resistant. Genetic tests showed that the Cf2, gene conditioned immunity and that the Cf4 gene provided resistance.

The possibility of producing herbage of higher quality than that of tall fescue (Festuca arundinacea) in a continental climate with cold winters, hot summers and low precipitation was investigated, with and without irrigation, at Taigu, Shanxi, China. Tall fescue was compared with perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis) and perennial ryegrass × meadow fescue in field swards, managed by cutting, during the year of sowing and in the three subsequent years. Perennial ryegrass yielded well in the year of sowing, but was low yielding subsequently; perennial ryegrass × meadow fescue yielded well in the year of sowing and in the following year. Both of these grasses had high rates of leaf appearance and extension and a high proportion of cell content in the dry matter. Tall fescue yielded well, but was low in proportion of cell content.

The experiment, designed to investigate the production of alfalfa in Saudi Arabia, was a factorial involving three irrigation rates and three cutting heights. The irrigation rates were sub-optimum, optimum and super-optimum, supplying 2730, 3850, and 5040 mm of water over the duration of the experiment respectively; cutting heights were low (2 cm), high (8 cm) and alternate (2 cm and 8 cm). The experiment ran for a year, with 14 harvests. Sub-optimum, optimum and super-optimum irrigation treatments produced 27·5, 31·4 and 31·9 tonnes of DM per hectare respectively. Proximate analysis of crude fibre, crude protein, and ash percentage were determined, and plant density and weed infestation recorded.

Observations that are frequencies rather than measurements often call for special types of statistical analysis. This paper comments on circumstances in which methods for one type of data can sensibly be used for the other. A section on two-way contingency tables emphasizes the proper role of χ2 a test statistic but not a measure of association; it mentions the distinction between one-tail and two-tail significance tests and reminds the reader of dangers. Multiway tables bring new complications, and the problems of interactions when additional classificatory factors are explicit or hidden are discussed at some length. A brief outline attempts to show how probit, logit, and similar techniques are related to the analysis of contingency tables. Finally, three unusual examples are described as illustrations of the care that is needed to avoid jumping to conclusions on how frequency data should be analysed.

Much of the watermelon (Citullus lanatus) cultivation in Brazil is conducted in sandy soil and topographic conditions that favour the erosion process. Therefore, conservation tillage methods are critical for the sustainability of the production chain of this vegetable crop. We studied different tillage methods and cover crops in watermelon cultivation in the area of the reform of degraded pasture. For this purpose, two tillage methods were established as experimental treatments: minimum tillage preparation with subsoiling only, and no tillage. As cover crops white lupine (Lupinus albus) and bristle oat (Avena strigosa) were seeded. As control, watermelon was cultivated with conventional tillage, without prior cultivation of cover crops. For the experimental design, randomised blocks in a factorial arrangement with four replications were used. After liming and phosphate fertilisation of the soil, cover crops were cultivated in soil with minimum tillage and no tillage to produce straw to be used for soil cover, where subsequently the watermelon was grown. The productivity of dry mass and nutrient accumulation in the shoot of cover crops, the soil properties and the watermelon agronomic performance were evaluated. White lupine had better performance in the production of dry mass and nutrient accumulation in shoot than bristle oat. There were differences among treatments for soil penetration resistance, where in conventional tillage the values were lower in the first 30 cm of depth in relation to no-tillage cultivation. The tillage method also affected the fertility of the soil at a depth of 0 to 20 cm. The no tillage provided increased nitrogen leaf content in watermelon regardless of cover crops but restricted root growth in relation to minimum tillage and conventional tillage. Watermelon had similar commercial production by different treatments, with reduction only in no tillage on bristle oat straw.

In nine breeding trials with cocoa in Ghana the experimental trees were interplanted with temporary trees of a standard variety as ‘calibrators’. The calibrators were removed after 2–2½ years before there was strong competition with the permanent trees. Trunk diameters of the calibrators were used as covariates in analyses of trunk size and yield of dry cocoa up to 7 years after planting, giving reductions in standard errors of differences between progenies of up to 25% in analyses of size and 15% in analyses of yield.

The possibility of growing grasses of higher quality than tall fescue (Festuca arundinacea) in a continental climate with cold winters, hot summers and low precipitation was investigated with and without irrigation at Taigu, Shanxi, China. Tall fescue was compared with perennial ryegrass (Lolium perenne), meadow fescue (Festuca pratensis) and a perennial ryegrass × meadow fescue hybrid cultivar in field swards, managed by cutting, during the year of sowing and in the three subsequent years. Tall fescue persisted satisfactorily throughout the experiment, even without irrigation. With irrigation, the other three grasses persisted satisfactorily to the end of the second harvest year and fairly satisfactorily to the end of the third harvest year. Without irrigation, the other three grasses had incomplete ground cover in the second harvest year and did not recover from the third winter.

Twenty-five cultivars of soyabean (Glycine max (L.) Merr.), differing in their origin, crop duration and seed size, were planted four times at bi-weekly intervals during the major rainy season at Ibadan, Nigeria and harvested at optimum maturity or two weeks later. Delayed harvest and intense rainfall during pod maturation were essential for selecting for resistance to field weathering, but 2 weeks' delay enabled susceptible and resistant cultivars to be identified. Percentage of infected seed had the highest correlation with potential germination at harvest (r=−0·869**) but may not be a suitable criterion for use in a screening programme. An alternative would be to screen cultivars for resistance to weathering on the basis of seed size and the proportion of smooth and clean seed, since these characters were highly correlated to potential germination (r=−0·562** and 0·632** respectively).

Low levels of zinc are reported in flooded rice grown on alkaline clay soils in the Lake Chad basin, north-east Nigeria. Zinc was added at 0, 5, 10 and 20 kg/ha to sample plots. For the untreated plots, the mean levels of zinc in young rice leaf and ‘available’ zinc in the supporting soil, using the alkaline extractant method of Trierweiler and Lindsay (1969), were 18·2 and 0·33 ppm respectively; corresponding mean levels for plots with 20 kg/ha added zinc were 36·5 and 1·54 ppm. There is a correlation between the two variables of r=+0·61 (P<0·01). Levels of nitrogen, phosphorus, potassium, magnesium and calcium in the rice leaf are also reported.

The quality of bean pods was influenced to a large degree by the variety, season of planting and the precise time of harvesting. The varieties Tenderette, Executive and Bush Blue Lake 274 were outstanding in their concentrated yield and pod quality. The development of seeds in the pods was faster in beans planted during the spring than in the autumn. Thickening of the pods during ripening was more rapid in the autumn than in the spring season. Outstanding differences were found between varieties with regard to the speed of seed development during pod ripening. As opposed to the outstanding differences between varieties with regard to quality characteristics, the differences with regard to yield were generally small and without economic importance.

Farmer surveys have consistently shown maize storage losses to be of primary concern to farmers in the western highlands of Cameroon. Past attempts at evaluating these losses, however, have proved to be unsatisfactory, mainly because of failure to consider qualitative, as well as quantitative, losses or to take account of consumption patterns (that is, timing and end use). A simulation model is presented that overcomes these deficiencies while providing a reliable estimate of the economic value of storage losses to the farmer, albeit at the cost of requiring fairly exacting data. The model is used to estimate the value of storage losses to farmers in the North West Province of Cameroon.

Propagules of five tall fescue genotypes, planted monthly, from April to December, made the greatest growth in April and September and the least in December. Despite the diverse geographic origin of the genotypes, there was no indication of interaction between genotypes and daylength. Propagules grew more vigorously when cut just above the basal leaf sheath then when cut to two or three inches in length. The complete removal of roots, which would facilitate planting, did not reduce growth and appeared to enhance the development of new roots. Propagules consisting of two or three culms grew more vigorously than those consisting of a single culm. Accordingly, if propagules were fragile or if survival was poor, two-culm propagules would become established more readily. Genotypes differed in growth rate even when planting weights were kept uniform. Results of this study could be used to reduce the time and cost of vegetative propagation of tall fescue.

Soil, water and leaf analyses were carried out on samples from irrigated orchards in the Jordan Valley. Analysis of the soil for available phosphorus and potassium gave meaningful results. Analysis of the irrigation water showed that a high sodium and chloride content caused an increase of these ions in the soil, which led to undesirable effects such as chlorosis. Irrigation water class C3–S1 should only be used if there is an annual precipitation of about 300 mm. Leaf analysis showed changes in the composition of leaves with age, but only potassium varied significantly between varieties. Standards of leaf, soil and water composition are suggested for the growing of citrus.