CCC applied to bread wheat, in 1967 and 1968 as a foliar spray at 1·40 and 2·28 kg./ha. a.i., prevented and/or delayed lodging to some extent. However, this effect was small and complete control of lodging seems to be unlikely, even when using large amounts. CCC increased grain yields, by 1·5 to 10·9 qu./ha., depending on the extent to which lodging was reduced. Significant depressions in yield were obtained, presumably owing to an observed increase incidence in ear diseases, particularly Septoria nodorum. The increase in grain yield was due mainly to an increase in 1000 grain weight and grains per ear, whereas the effect on tillers per unit area was slightly negative. Where no lodging occurred, there was a slight but non-significant tendency for increasing grain yields after CCC treatment.

The effects of three irrigation regimes on growth, yield and quality of cotton were investigated for two seasons in relation to earliness, quality and water-use efficiency, expressed as m. of water/kg. cotton produced. Light irrigations of cotton, at 75 mm. per irrigation every ten days, were economically better than the traditionally-accepted practice of irrigating every 14 days, and markedly better than prolonging the irrigation cycle to 20 days, mainly due to increased market value of the crop. The results also showed that irrigation intervals of 20 days, besides depressing yield, had a deleterious effect on fibre strength, though the different water regimes did not seem to affect other quality tests.

The problems resulting from genotype × environment interactions are discussed, giving an example where the application of statistical techniques to maize breeding makes it possible to assess the effects of such interactions. A method of maize breeding is proposed which enables a number of objectives to be achieved from a single breeding programme.

Foliar sprays of 25–100 mg L−1 dinitrophenol, sodium azide (NaN3) and thiourea solution applied to Azolla microphylla (strains 202 and 203) at seven days after inoculation significantly increased the sporulation frequency and number of micro- and mega-sporocarps per plant. Azolla biomass production was decreased by the application of NaN3 at 50–100 mg L−1 and dinitrophenol or thiourea at 75 and 100 mg L−1. Both the sporulation frequency and sporocarp number were maximal with dinitrophenol and NaN3 at 100 mg L−1 and thiourea at 75 mg L−1. At this concentration, NaN3 was more effective than dinitrophenol and thiourea in enhancing sporulation in A. microphylla (strain 203). The sporulation frequency and micro-sporocarp number were significantly higher with gibberellic acid (2.5 mg L−1) than with indole acetic acid (6 mg L−1) application, while the effects of NaN3 were comparable with those of gibberellic acid. The mega-sporocarp numbers in these treatments were comparable. The combined application of any two of the metabolic inhibitors had antagonistic effects and decreased the sporulation frequency and sporocarp number over their individual applications. Combined applications also substantially reduced the biomass production. The application of gibberellic acid or indole acetic acid along with one of the metabolic inhibitors had synergistic effects on the formation of sporocarps and significantly increased the biomass production, irrespective of the metabolic inhibitor treatment. The number of both micro- and mega-sporocarps in the gibberellic acid + NaN3 and indole acetic acid + NaN3 treatments, and micro-sporocarps in the gibberellic acid + dinitrophenol, indole acetic acid + dinitrophenol and indole acetic acid + thiourea treatments was significantly higher than when each of these chemicals was applied alone. Of the different combinations of gibberellic acid, indole acetic acid and NaN3, gibberellic acid + NaN3 recorded the highest sporulation frequency and micro-sporocarp number, and indole acetic acid + NaN3 the highest mega-sporocarp number. Application of all three chemicals together had no extra advantage.

Genotypic correlations and path coefficients were used to determine the importance of various characters as components of yield in castorbean. Number of primary branches per plant and 100-seed weight had high positive correlations with yield per plant and with each other. Oil content was significantly and positively correlated with 100-seed weight. The path analysis revealed that number of clusters per plant, number of branches, height at maturity and yield of the first spike had the highest direct effect on yield per plant. Sixteen selection indices were constructed using these four yield components, the index combining all four being about 54 per cent more efficient than straight selection based on yield alone.

Variety, spacing and harvesting date trials with fodder beet were carried out in Cyprus under rainfed conditions. The variety Polyrossa gave the highest dry matter (DM) yield, 12,906 kg/ha. Yield of DM increased linearly with population density to an optimum spacing of 45 × 20 cm. Yields of beet decreased slightly when harvested after 15 June and significantly when harvested after 29 August. Irrigation with saline water increased DM yields.

The present study evaluated the pest constraints of an innovative crop management system in Cameroon involving conservation tillage and direct seeding mulch-based strategies. We hypothesized that the presence of mulch (i) would support a higher density of phytophagous arthropods particularly millipedes as well as pathogenic fungi that cause severe damage to cotton seedlings and (ii) would reduce early aphid infestations. The impact of two cover-crop mulches Calopogonium mucunoides and Brachiaria ruziziensis on the vigour of seedling cotton stands and arthropod damage was assessed in two independent field experiments conducted in 2001 and 2002 respectively. In both experiments the presence of mulch negatively affected cotton seedling stand by 13–14% compared to non-mulched plots and the proportion of damaged seedlings was higher in mulched than in non-mulched plots supporting the hypothesis that mulch favoured soil pest damage. In both experiments insecticidal seed dressing increased the seedling stand and the number of dead millipedes collected and fungicide had little or no effect on seedling stand and vigour. It was however observed in 2002 that the fungicide seed dressing had a positive effect on seedling stand in non-mulched plots but not in mulched plots suggesting that fungi may have been naturally inhibited by B. ruziziensis mulch. The dynamics of aphid colonization was not influenced by the presence of mulch. In 2001 taller seedlings were found in mulched than non-mulched plots probably due to greater water and nutrient availability in C. mucunoides-mulched plots than in non-mulched plots.

Dry weight, stem and branch length and node number, and flower and fruit number where appropriate, were recorded through the season on cotton, groundnuts, kenaf and sesame in the central rainlands of the Sudan in 1965. For each sampling date variation within plots and betweenreplicate plots within blocks and treatment x block interaction have been studied, together with the effect of these components on the magnitude of the residual root mean square in the analysis of treatments x blocks. The main components were usually within plot and between replicate plots within block errors. Uncontrolled variation was unacceptably great, and was thought to be in large part the result of irregular surface drainage conditions. It seems more likely to be useful to include surface drainage contrasts in field experiments subject to high intensity rainfall on this impermeable clay soil than to attempt to increase precision alone.

On-farm research in remote areas demands methods that keep down costs and reduce the need for subsequent research and extension inputs and yet that still produce useful and sustainable recommendations. An important part of the process is to identify existing resource user groups and use them, rather than individual farmers, as a starting point for on-farm research. This approach is discussed in the context of farming systems research in the eastern hills of Nepal.

Many of the papers submitted to this Journal fall far short of the standard of presentation that editors are entitled to expect. This tends to sour the all-important relation between editor and author, making unnecessary work for the former and perhaps even prejudicing acceptance of the latter's paper. The author, typist, editor and copy-editor have specific roles to play in preparing copy for the compositor and this article explains those roles, in the hope that the explanation may help authors to present their papers in the correct form.

In trials with Helianthus annuus in the highlands of Kenya it appeared that the major constraints for successful utilization of sunflower for forage were: high lodging susceptibility; low DM percentage of the forage; low D-value of the forage when high yielding ( = tall) cultivars are used; and poor silage making characteristics. The proportion and quality of the stem largely governed the nutritive value of the whole plant. A reduced proportion of stem would improve all four constraints, but DM yield would also be reduced. Protein yields were highest at the beginning of flowering, but DOM yields were highest about 9 days later, towards the end of flowering. DM yields were highest towards physiological maturity of the seeds.