The correlation between sorption and mobility of potassium in illitic soils has been used to compare K leaching in profiles under different fertilizer treatments in longterm experiments. Estimates of potassium saturation of the cation exchange capacity in 15 cm soil layers to a depth of 225 cm indicated maximum leaching of K in unfertilized soils. Application of N, P and K increased K uptake by plants, reduced K saturation and thus its leaching.

Tubers produced by potato plants grown in vermiculite and supplied with either 0, 1 or 3 mM calcium chloride solution developed brown necrotic lesions of internal rust spot. Plants supplied with 9 and 27 mM calcium chloride solution did not show the symptoms and had a substantially greater concentration of calcium in the tuber dry matter. It is concluded that internal rust spot is a physiological disorder associated with a low concentration of calcium in the affected tubers.

The response to dietary inclusion of NaCl or NaHC03 at 42 and 60 g/kg (18 g Na/kg) respectively was examined in relation to rumen fermentation and the flow of nutrients to the duodenum of calves.

Measurements were made with four calves on each diet at 8 and 11 weeks of age: weaning having taken place at 5 weeks of age.

Osmotic pressure, pH, total VFA concentration and molar proportions of VFA were not significantly affected by the treatments imposed. Rumen dilution rate was increased by 28% on the NaHCO3 diet compared with the other two diets but this difference failed to achieve statistical significance. Mean duodenal flows of organic matter, modified acid detergent fibre and total amino acids were 0·52, 0·72 and 1·25 of the respective dietary intakes and were not significantly affected by the treatments imposed. NaHCO3, however, significantly increased the supply of α-linked glucose polymer to the small intestine (15% of dietary intake) compared with the control (4%) and NaCl (6%) diets. The results demonstrated that NaCl and NaHCO3 had small effects upon the digestion within the rumen of young calves with specific reference to flow of nutrients to the proximal duodenum. It is suggested that the stimulatory effect of NaHC03 on food intake and performance of calves may be attributable to an increase in rumen buffering capacity, and some indication of an increase in the fractional outflow rate of water and possibly particulate matter from the rumen.

Six experiments carried out over 3 years investigated the effects of the date of defoliation of the seed potato crop and the storage temperature of the seed on the growth of the subsequent ware crop.

Defoliation of the seed crop in July tended to reduce foliage dry weight particularly at later harvests, and in two experiments in 1974 affected the tuber yield. In one of these experiments defoliation in July resulted in a lower yield than from defoliation in August, while in the other experiment it significantly reduced the bulking rate of the ware crop and gave a lower yield of King Edward at the final harvest. Storage of the seed tubers at low temperature (2–3 °C) tended to increase the amount of foliage produced but only in two out of six experiments was there any effect of storage temperature on yield; in both storage at low temperature gave the lowest yield.

There was a significant relationship between the effect of storage temperature on tuber yield and its effect on the time to emergence of 50% of the plants. It is suggested that in these experiments a combination of late planting and weather conditions before emergence reduced the effect of storage temperature on the time to 50% crop emergence and therefore reduced its effect on tuber yield.

In 1973 when there was a large effect of storage temperature on yield, there was a significant relationship between the tuber yield of the ware crop and the physiological age of the seed measured as accumulated day degrees above 0 °C from dormancy break to planting.

Studies of ewe behaviour are not only necessary to facilitate management procedures but also to ensure high productivity. Indeed, information on the ewe behaviour during parturition would help in reducing ewe and lamb wastage, but there is little information available. This paper gives information on the diurnal variation in lambing and time taken for placenta expulsion in Awassi ewes.

In many field investigations of cereal growth, stages of crop development may be described adequately using the Feekes scale (Large, 1954) or the more recent decimal code (Zadoks, Chang & Konzak, 1974). For example, the onset of stem extension (Feekes stage 6; decimal code 31) is frequently taken as a field indication of the switch from vegetative to reproductive growth. However, in investigations of the influence of soil properties, especially temperature, on shoot apex and leaf growth, it is important to know (a) the position of the apex below the soil surface during the early stages of development and (b) the timing of the rise of the apex above the soil surface.

The triple test cross analysis (Kearsey & Jinks, 1968; Jinks & Perkins, 1970) was used to detect and estimate the additive, dominance and epistatic components of genetic variation for four metric traits, namely, final plant height, number of spikelets per spike, 100-kernel weight and yield per plant, in the first backcross populations of four wheat crosses (Norteno 67 α Moti, Sonalika α Moti, Kalyan Sona α Sonalika and Kalyan Sona × NP 876). Epistasis was a more important component of variation for final plant height and yield per plant than for number of spikelets per spike and 100-kernel weight. On the other hand, the additive component was highly significant for all four characters in all eight backcrosses.

A wealth of information is available concerning the ‘normal’ gastrointestinal mechanisms within various species of herbivores (Alexander, 1962; Church, 1971; Quarterman, Phillips & Lampkin, 1957). In addition, the effect that dehydration has upon the physiology of digestion has also been investigated (Schmidt-Nielsen et al. 1956; Schmidt-Nielsen, 1964; Maloiy, 1972; Macfarlane et al. 1972). This communication presents preliminary observations on the effect that dehydration hasupon gastrointestinal water content, as a percentage of total gut contents, and fluid osmolality (m-osmol/kg H2O). A comparison was made under controlled laboratory conditions between six species of domestic herbivores fed identical diets and exposed to a simulated desert environment

In the winter-rainfall areas of southern Australia cattle and sheep grazing dry pastures in late summer and early autumn commonly lose weight because of a decline in the availability and nutritive value of the dry herbage (McLaughlin, 1973). Early-weaned calves and young lambs are affected more severely than older animals probably because of their low feed intake and their high requirements for energy and protein (Preston & Willis, 1970).

Sesamum phyllody is a serious disease of sesame (Sesamum orientale L.). The disease is mainly spread by the leaf–hopper vector Orosius albicinctus Distant (Ghauri, 1966). The biology and bionomics of the hopper was worked out by Bindra & Singh (1970). The relative fecundity–cum–fertility and longevity of the hopper on the diseased and healthy plants were studied to supplement the existing information.

It has been shown (Gordon, 1975) that certain progestagens administered intravaginally can be highly effective in the control of oestrus, ovulation and fertility in ewes. Prostaglandin (PGF2α) when infused into the uterine vein ipsilateral to the ovary containing the corpus luteum has been shown to result in luetolysis and a return to oestrus in a high proportion of ewes (Hearnshaw, Restall & Gleeson, 1973). Synthetic analogues of PGF2α have also been shown to have a marked luteolytic effect in ewes (Baird & Scaramuzzi, 1975). Variable fertility has been reported following the use of prostaglandin or its analogue for oestrous synchronization (Jennings, 1975; Haresign, 1976; Fairnie, Cumming & Martin, 1976; Lightfoot, Croker & Marshall, 1976; Trounson, Willadsen & Moor, 1976). Low fertilization has been reported after the use of a prostaglandin analogue and artificial insemination at a predetermined time in ewes (Boland, Gordon & Kelleher, 1978). The purpose of the present experiment was to extend these observations, using a ram in natural service after employing a double prostaglandin injection regime or an intravaginal progestagen treatment for the control of oestrus in cyclic sheep.

An observed positive correlation between tuber sprout growth in store and yield and tuber weight was due to the association of short sprouts with small tubers (less than 75 g). Sprout growth in larger tubers appears to be unaffected by tuber weight.

With the development of effective methods of oestrus synchronization (Gordon, 1975), it is now possible to breed ewes at most times of the year. Encouraging conception rates have been reported following insemination (Colas & Brice, 1970; Colas et al. 1973; Gordon, 1975). A major disadvantage with the technique is the need to inseminate ewes twice at 10–14 h intervals. Because of the anatomy of the ovine cervix, it is not possible to deposit semen in the uterus as in the bovine. The present experiment was designed to compare a single or double insemination with natural service. Two types of inseminating gun were employed in an effort to deposit semen deep in the cervical folds.

There is evidence that selection for small body size in mice results in a decrease in the total number of muscle fibres in a given muscle (Luff & Goldspink, 1967; Hanrahan, Hooper & McCarthy, 1973). It has also been shown that small chickens have fewer muscle fibres in certain muscles than larger chickens (Smith, 1963). This type of work has not, however, been extended to a study of the larger domestic animals. At Göttingen in Germany, Haring et al. (1966) have developed a breed of miniature pig which, at 6 months of age, was about a third of the body weight of commercial pigs. We therefore decided to investigate the muscles of these miniature pigs and compare them with commercial pig muscles, paying particular attention to the number of muscle fibres.