Rumen ammonia levels in animals given silage diets are generally high and there appears to be considerable scope for improving the utilization of ammonia for microbial protein synthesis (Thomas & Chamberlain, 1982). Chamberlain et al. (1985) showed that supplements of sucrose were more effective than supplements of starch in reducing the rumen ammonia levels in animals given silage diets. Moreover, the effects of sucrose were increased when it was given together with sodium bicarbonate. The implication was that the sucrose supplements increased the fixation of ammonia in microbial protein through the provision of additional fermentable energy, and that this process was enhanced by the sodium bicarbonate supplements. The experiment reported here was designed to provide quantitative information on these effects and in particular to elucidate more fully the effects of sodium bicarbonate supplements on nitrogen metabolism in the rumen.

Sugar beet has never been grown commercially in Cyprus. Sugarcane was grown in the Middle Ages but its cultivation has since gradually declined, and none has been grown in the last 200 years (Aristidou, 1986). Recently a research programme was undertaken to assess the feasibility of growing sugar beet so that imports of sugar may be reduced. Sugar yields of up to 20 t/ha (165 t fresh roots/ha) were obtained in a coastal area (Akhelia) when the crop was sown in November and harvested in July–September (Hadjichristodoulou, 1984, 1987). Because the period April–October is practically rainless, the crop has to be irrigated, but with November sowing full advantage is also taken of the winter rainfall.

Previous attempts to study the effect of virus infection on nitrogen-fixing ability of some legumes (Tu, Ford & Grau, 1970; Singh & Mall, 1974; Gupta & Joshi, 1976; Tu & Holmes, 1980) concentrated mainly on the effect of virus infection on the extent of nodulation or on the amount of nitrogen fixed by diseased plants or both. The effect of virus infection on the bacterial population and the physiological status of virus-infected nodules has received little attention.

Incubation of feed samples in nylon bags in the rumen has been used extensively to evaluate the rate and extent of dry matter, protein, starch and cellulose degradation (Mehrez & Ø0rskov, 1977; Mehrez, Ørskov & McDonald, 1977; Ganev, Ørskov & Smart, 1979; Weakley, Stern & Satler, 1983) and to predict the energy values of ruminant feeding-stuffs (Cottyn et al. 1984).

The most harmful of gaseous air pollutants include ozone (03), sulphur dioxide (SO2) and nitrogen dioxide (N02). These three pollutants are responsible for up to 90% of the total crop losses due to air pollution (Heck et al. 1981). Reduction in crop yield is one of the most common consequences of pollutant-crop interaction (Koziol & Whatley, 1984; Treshow, 1984). Mean yields of four soya-bean cultivars, York, Dare, Cutler and Clark, grown in open-top chambers with non-filtered air, were reduced by 20% compared with those grown in carbon-filtered air (Kohut et al. 1982). The major components affected were number of pods, number of seeds per filled pod and weight of seeds; a linear reduction in seed weight per plant was reported with increasing concentration of O3.

Tasmanian Merino sheep show a bimodal distribution in the concentration of reduced glutathione (GSH) in their red cells, 40% of sheep having GSH values of around 27 mg GSH/100 ml red cells and 60% with values of about 92 mg GSH/100 ml red cells (Tucker & Kilgour, 1972). The GSH deficiency was shown to be due to an impaired activity of γ-glutamyl cysteine synthetase (γ-GC-S), the enzyme catalysing the first step of GSH biosynthesis (Tucker, Kilgour & Young, 1976). Family data indicated that the deficiency in this strain of Merinos was under the control of a dominant gene, designated GSHL (Tucker et al. 1976). In contrast, Board, Roberts & Evans (1974) reported that a similar type of GSH deficiency in Australian Merino sheep was under the control of a recessive gene. The reasons for this apparent discrepancy remain unresolved.

One of the most widely used methods of root study involves obtaining soil cores and washing the roots contained free of soil (Wellbank & Williams, 1968; Ellis & Barnes, 1971; Kolesnikov, 1971; Schuurman & Geodewaagen, 1971; Bohm, Maduakor & Taylor, 1977). However, the process of root washing is time consuming and laborious. Some of the washing assemblies elsewhere (Peyev, 1952; Schuurman & Goedewaagen, 1971; Wellbank et al. 1974) have not gained popularity with researchers in developing countries because of the high costs involved or the sophisticated facilities needed. There is therefore a need for a low-cost root washing apparatus which can be fabricated with locally available materials. This note reports the development of such an apparatus.

Corolla colour in chickpea (Cicer arietinum L.) is white or various shades of pink or blue (Smithson, Thompson & Summerfield, 1985). Normally, a leaf axil subtends a single peduncle bearing a single flower but ‘double-flowered’ types, where a pro-portion of the peduncles subtends two flowers, are not uncommon and produce 6–11 % more seed yield than the normal single-flowered type (Sheldrake, Saxena & Krishnamurthy, 1978)

The Agricultural Research Council (1980) has recently published revised estimates of the phosphorus requirements for ruminants. These new estimates are considerably lower than those formerly recommended (Agricultural Research Council, 1965) and some concern has been expressed as to whether or not they are adequate (Cooke, 1982; Todd, 1983).

Japanese mint, an important essential-oil-bearing crop, is cultivated for menthol used in cosmetic and pharmaceutical industries. It requires a high level of nitrogen fertilizer, between 150 and 250 kg N/ha depending on the agro-climatic conditions (Ghosh & Chatterjee, 1976; Yadav, Mohan & Ram, 1983). During the crop cycle (January–August), frequent irrigations and high intensive rains result in poor N recovery especially on light-textured soils. With a view to reduce losses of N and improve N recoveries, the relative efficiency of neem-cake-coated urea, laccoated urea and urea supergranules has been investigated in comparison with prilled urea in Japanese mint.

Pearl millet is the choice crop in the semi-arid tropics. Strong winds, intense storms, high solar radiation and extreme temperatures are characteristics of these zones. Germination and seedling establishment are the major problems and are commonly associated with low moisture availability, high temperature of the soil and soil crusting. Water stress can affect germination by delaying initiation of germination, slowing rate of germination or by decreasing final germination percentage.

The treatment of straw using ammonia released by the hydrolysis of urea and subsequent improvements obtained in digestibility of straws have been reported (Jayasuriya & Pearce, 1983; Williams, Innes & Brewer, 1984). Benefits achieved by this method compare well with those obtained by sodium hydroxide (Verma, 1983). Urea is widely and cheaply available in many developing countries; this favours its use in improving nutritive values of low quality roughages. In addition, this method is relatively safe, uncomplicated and inexpensive compared with some other chemical treatments. Considerable attention has been paid to the treatment conditions for treating cereal straws with liquid or anhydrous ammonia which lead to the optimum effects (Waagepetersen & Vestergaard Thomsen, 1977; Solaiman, Horn & Owen, 1979; Borhami & Sundstøl, 1982), but equivalent studies on the ammoniation of crop residues through urea are limited (Cloete & Kritzinger, 1984; Singh & Negi, 1985). No report is available on the changes in in sacco dry-matter digestibility (DMD) of urea ammoniated straw during treatment at different temperatures. This paper describes our observations on the changes in in sacco DMD of urea ammoniated wheat straw at different treatment times and temperatures.