Mainstem leaf appearance and leaf extension were monitored at 7-day intervals throughout the vegetative development of field-grown winter wheat plants, during two growing seasons 1977–9. Using hourly air and soil temperature records, it was found that the rate of leaf appearance was controlled by soil temperature, with the best linear relationships being obtained using accumulated soil temperature above a base temperature of 0 °C at 1 and 5 cm depth. Leaf appearance could be predicted equally well using 09.00 G.M.T. screen air temperatures although deviations from each linear relationship were found during very cold periods when slow leaf extension rates delayed leaf appearance.

Leaf extension was also found to be linearly related to temperature, with the best fit being obtained using accumulated soil temperature above 2·5 °C at 5 cm depth, suggesting a threshold of 2·5 °C for leaf extension. The response to temperature (extension per unit of accumulated temperature) was the same for all the leaves of a given plant, or sowing date; however, the fact that the rate of leaf extension increased progressively with sowing date suggests that plant response to temperature may be determined at crop emergence (possibly mediated by rate of change of day length). Leaf extension rates could be predicted satisfactorily using 09.00 G.M.T. soil temperatures (5 or 10 cm) but less so using screen air temperatures.

The prediction of plant leaf areas or crop leaf area indices using such relationships between temperature and leaf growth was found to be hampered by rapid and irregular rates of leaf senescence.

A field experiment was conducted on a saline sodic soil at Kanpur to study the effects of sedimentary pyrites and Zn on the yield, Zn and Ca utilization by rice and wheat crops and on the amelioration of saline sodic soil. The grain yield of the first crop of rice increased from 1·55 t/ha for the ‘control’ to 3·44 and 4·01 t/ha with the 40 and 80% gypsum requirement pyrites treatments. The grain yield of succeeding wheat and rice crops also increased significantly owing to pyrites residues. The favourable effect of pyrites on crop yield was associated with an appreciable decrease in the pH, electrical conductivity and exchangeable and soluble sodium content of the soil resulting in greater utilization of Zn and Ca by the crops. Zinc applications also greatly increased grain yield and Zn uptake by the crops. The higher levels of pyrites with adequate N, P and K fertilizers but without Zn did not give yields that were obtained by adding 11 kg Zn/ha.

Significant yield responses were observed in the succeeding wheat and rice crops to Zn residues from the higher Zn treatments. The ‘pyrites+Zn’ treatment was most effective in decreasing the Na content and enhancing Ca uptake which increased the Ca/Na ratio in plants. The Zn treatment alone also decreased soil pH, electrical conductivity and exchangeable Na.

Two experiments investigated the effects of raising crisp lettuce seedlings under different environmental conditions prior to transplanting, on transplant size and weight and head weight at maturity.

The use of tungsten lighting for 4 h after the end of a 12 h period of fluorescent and tungsten lighting increased transplant size and weight and the weight of heads at maturity compared with fluorescent and tungsten lighting only. Glasshouse-raised transplants were larger than those raised under artificial lighting but gave heads of similar weight to transplants which had supplementary tungsten lighting for 2 weeks. Both these treatments gave significantly heavier heads than a drilled crop or plants raised without supplementary tungsten lighting. Increasing the number of weeks of the supplementary lighting treatment tended to increase the coefficient of variation (c.v.) of head weight. Nevertheless the drilled crop had a higher c.v. of head weight than any transplanted treatment.

The variety Pennlake produced pointed (‘coned’) heads when grown in the open and its leaves were shorter and broader than those of plants grown in polyethylene tunnels, which did not show ‘coning’. It is suggested that ‘coning’ occurs primarily as a result of either lower mean temperatures or a lower amplitude of temperature when grown in the open. It occurred most frequently with glasshouse-raised plants indicating that a higher raising temperature may also contribute to the problem.

Two experiments at Wellesbourne studied the effects of cold treatments on the leaf and curd production characteristics of a range of annual and biennial varieties of cauliflowers.

Cold treatments delayed curd initiation and had a variable effect on the final number of leaves, but reduced the spread of curd initiation of plants which were 5 weeks old when cold-treated. The overall rate of leaf production and the final number of leaves generally increased with later-maturing varieties while initial rates of curd expansion generally declined.

The annual varieties produced a small number of leaves and fairly synchronously formed a curd which developed rapidly; the biennial varieties had a higher rate of leaf production after transplanting and then changed to the generative state over a more prolonged period, following which the curd developed slowly.

Two potential new kale cultivars were compared with five control cultivars in 12 trials involving five sites in the north of England and the south of Scotland, 2 years, and a range of sowing and harvest dates.

The differences between cultivars were small for dry-matter and digestible organic-matter yield. Genotype-environment interactions were relatively large by comparison and hence only tentative estimates could be made of relative yield performance in a wider range of environments. However, the set of trials was satisfactory for determining the heights, dry-matter contents and digestible organic-matter contents of the cultivars despite the presence of statistically significant genotype-environment interactions.

Joint regression analyses revealed that the two cultivars with the lowest mean freshweight yields were also the least responsive to environmental change and that environments resulting in low digestible organic-matter contents were best for discriminating between cultivars.

The effect of treating soya-bean meal with formaldehyde was studied in cattle by supplementing a hay–barley diet with two levels of either untreated or formaldehydetreated soya-bean meal. The formaldehyde treatment had no significant effect upon apparent N digestibility in the whole tract; it increased the amounts of non-ammonia N and amino acid N entering the small intestine but this increase was not statistically significant. However, increasing the proportion of either soya-bean meal in the diet increased the flow of non-ammonia N to the small intestine and apparent N digestibility in the whole tract. The formaldehyde treatment reduced the apparent degradability of the soya-bean meal N, determined in vivo from 0·74 for the untreated meal to 0·38 for the formaldehyde-treated meal. The in sacco technique produced values for the apparent degradability of the two soya-bean meals which ranked them in a similar manner as did the in vivo technique but gave lower values for degradability than the in vivo technique.

The objective of this study was to examine the effect of the chemical growth regulator chlormequat on the yield and yield components of oil-seed rape. Although this chemical is widely used in wheat production systems, its use as a morpho-regulator for oil-seed rape has not been examined thoroughly. A few Eastern European experiments have been published. Voskerusa (1972) applied it at 2, 4, 6 and 8 kg/ha to winter varieties in Czechoslovakia. His results, which agree with those of Fabry & Hannich (1972), demonstrated reduced winter kill using an autumn application. However, studies on modern varieties such as Rafal, now widely grown in European Economic Community countries, have not been reported in detail.

Pyrethrum flowers are widely used in different insecticidal formulations for controlling household insects and crop pests. The quick knock-down effect on insects, the low mammalian toxicity and the rapid decomposition of pyrethrins in the soil make it an ideal and safe insecticide. The flower yield in pyrethrum is influenced by plant population density and phosphate fertilizer application (Nair, 1955; Kroll, 1962, 1963; Parlevliet, Muturi & Brewer, 1968a, b). Parlevliet et al.(1968a, b) recommended a spacing of 60 × 30 cm whereas Nair (1955) suggested a spacing of 75 × 60 cm for obtaining higher flower yields in this crop. The present investigation was made to compare the effects of different spacings and rates of nitrogen application on the flower and pyrethrin yields of pyrethrum.

It has long been known that the size and shape of sampling units used to assess crop yield may have significant effects upon the precision of the estimates (Smith, 1938; Hudson, 1939) but little is known about the effects when estimating incidence of disease. Gilligan (1980) showed that estimates of the incidence (i.e. presence or absence of disease) of stem canker (Phomx, lingam, perfect state Lepto sphaeria maculans)of oil-seed rape were more precise when large square sampling units rather than long rectangular units of similar area or small square sampling units were used. Moreover, estimates derived from the frequently used method of sampling by removal of 25 stems, supposedly at random from each plot, were shown to be biased.