The growth and development of two early (Pusa ageti and T-21) and three mediumduration (ST-1, ICP-1 and HY-3C) cultivars of pigeonpea (Cajanus cajan (L.) Millsp.) were compared at Hyderabad, India, in 1974 and 1975; in 1976 cv. ICP-1 was studied. The pigeonpeas were grown on a Vertisol and on an Alfisol. The crop growth rate in the first 2 months was low. The maximum rate of 171 kg/ha/day was found in the fourth month of growth of cv. ICP-1 on Alfisol. The early cultivars, one of which (cv. Pusa ageti) was morphologically determinate, and the other (cv. T-21) indeterminate, did not differ in the proportion of dry matter partitioned into seeds. The mean dry weight of the ab ove-ground parts of the medium cultivars on Vertisol in 1975 was 8·45 t/ha, including 2·23 t/ha of fallen plant material. The mean harvest index (ratio of grain dry weight to total plant dry weight) of these cultivars was 0·24 excluding fallen material and 0·17 taking fallen material into account. Starch reserves were present in the stems during the vegetative phase, but disappeared during the reproductive phase. In 1974 the maximum leaf-area index on Vertisol was 3 and on Alfisol 12·7. The net assimilation rate tended to decline throughout the growth period, but in the medium cultivars increased at the end of the reproductive phase, probably because of photosynthesis in pod walls and stems.

In 1974 and 1975 the growth of roots and distribution of nodules in Vertisol was investigated by means of soil cores. Roots extended below 150 cm and root growth continued during the reproductive phase. Most nodules were found within the first 30 cm of soil, but some were found below 120 cm. In cv. T-21, grown in brick chambers150 cm deep, at the time of harvest about three-quarters of the mass of the roots was found in the first 30 cm, and the shoot:root ratio was around 4:1.

In 1975 the mean uptake of nitrogen by the medium cultivars on Vertisol was 120 kg/ha, including 34 kg/ha in fallen material. In 1976 the uptake of nitrogen by cv. ICP-1 was 89 kg/ha on Vertisol and 79 kg/ha on Alfisol, including 32 and 23 kg/ha respectively in fallen material. Nitrogen uptake continued throughout the growing period. The percentage of nitrogen in stems and leaves declined as the plants developed and there was a net remobilization of nitrogen from these organs. The pattern of uptake and remobilization of phosphorus resembled that of nitrogen. In 1976 the total uptake of phosphorus by cv. ICP-1 on Vertisol was 5·8 kg/ha and on Alfisol 5·0 kg/a.

The relatively low yields of pigeonpeas result from a restricted partitioning of dry matter into pods, which may be related to the plants' perennial nature.

This paper describes the comparative semen characteristics (volume, motility, sperm density, number of sperms, percentage live and abnormal sperms) of Corriedale (exotic) and Marwari and Jaisalmeri (indigenous) rams during the summer and rainy seasons under the arid conditions of Jodhpur, in northwestern India. Except for sperm density, the semen of indigenous animals was superior to that of the Corriedale, although the differences recorded were not of a magnitude to cause the Corriedale sheep to be considered reproductively ineffective under hot arid conditions, if managed properly. The present findings do not conform to the earlier views of the prevalence of ‘summer sterility’ in Corriedale rams observed under hot humid conditions but there appears to be a negative relationship between semen quality and atmospheric humidity. The Corriedale sheep are recommended for improving the sheep sector in the desert areas of Rajasthan.

Piglets in litters, paired according to farrowing date, were redistributed during the first day after birth according to two schemes. In scheme AC–BD, one sow of the pair received the heaviest and the third heaviest quarters of the combined litters (based on weight post partum), while the other sow received the second heaviest and the lightest quarters. In scheme AB–CD, one sow received the heavier half, and the other the lighter half of the piglets. After 3 weeks under scheme AB–CD, the weight difference between the second and third quarters had become reversed, while under scheme AC–BD the difference was preserved. There was no evidence of a corresponding interaction in the selection of anterior or posterior teats. The rank correlation of the piglets' initial weight and suckling position was low for most sows. No marked differences were observed between fostered and unfostered piglets in the weight measures or suckling position. It is concluded that the growth of the piglets was influenced by the relative size of their litter-mates after redistribution, but that little of the effect could be explained by competition for the anterior teats.

Adult sheep, unweaned and mature weaned calves have been examined by metabolic studies for sodium balance. The ratio of sodium input/output was near unity with only a very small amount of the ingested sodium salt being retained. A positive sodium balance was always present, with excess sodium salt being excreted. The main channel of sodium excretion was the kidney, although when sodium intake was increased the sodium content of the faeces showed a proportional increase. Unweaned calves, a few days old, were quite able to excrete excess sodium salts in concentrated urine.

There was a clear difference in preference for sodium salts over water, between weaned calves allowed access to sodium salts while being fed milk, and weaned calves denied sodium salts at the milk feeding stage. Sodium-naive calves showed a marked preference for sodium salt solutions while the sodium-experienced calves showed at best an indifference and sometimes even an aversion. With continued access to sodium salts the volume ingested declined steadily in both groups but food intake remained constant.

In both calves and sheep the preference for sodium salts showed considerable variation between animals. The evidence from parallel metabolic studies suggests that this variation indicates that salt intake is controlled by some mechanism, possibly in the central nervous system, which is activated by dynamic sodium metabolism. Our experimental results confirm that ruminants have a well developed salt taste but predilection for sodium salts could be a biochemical manifestation rather than a hedonic propensity.

Two methods were developed for the rapid estimation of heat tolerance in plants using excised tissue pieces. The first method was a modification of the conductivity-bridge method and could yield results in less than 3 h. The second method combined plasmolysis with vital staining for the estimation of tissue injury following a regulated heat stress. This method was first developed and perfected using onion bulb epidermis tissue. It was later adapted for estimation of heat tolerance in intact tomato plants. Results from this method could be obtained within 1 h. The advantages and limitations of the two methods are compared and discussed.

Field experiments were made under natural rainfall during the winter seasons of 1972–3 and 1973–4 at the Indian Agricultural Research Institute, New Delhi, to study the soil water use by barley varieties as influenced by nitrogen rates, mulching and foliar application of antitranspirants. Both Ratna and Vijaya varieties of barley had similar efficiency of water use.

Total water use was not much different for various treatments but straw mulch and kaolin decreased evapotranspiration at tillering and pre-flowering stages enabling the plants to use more water at critical stages of grain formation. Application of nitrogen, straw mulch and a foliar coating of kaolin increased the efficiency of water use.

Pot experiments were carried out using a system in which root mats were in contact with a Danish soil for 24, 72 or 168 h. Different rates of K fertilizer (0–80 mg K/100 g soil) resulted in marked responses at 168 h of roots–soil contact, however moderately or little responses at 72 or 24 h had occurred. Marked reciprocal K–Ca, K–Mg, K–Na relationships with yield response to rates of applied K were attributed to both dilution and antagonism. The latter was not apparently brought about by competition for the carrier binding site but from the unspecific replacement competition which occurred in the interior of plant cells and not in the outer surface of the cell root membrane.

A series of irrigation experiments was done at Rothamsted where the soil is a flinty silty clay loam over flinty clay. The results are compared with those obtained by Penman (1962, 1970, 1971) at Woburn where the soil is a loamy sand over sand. The limiting deficits, Di, above which irrigation increased yields, were about 2·5 times greater at Rothamsted than at Woburn; this ratio approximates to the ratio of the water-holding capacities of the soils (– 0·1 to – 15 bar) to a depth of 1 m. The limiting deficits at Rothamsted were 80 mm for spring-sown field beans, 84 mm for main-crop potatoes, 100 mm for spring barley and 140 mm for spring and winter wheat. The responses to irrigation were not determined accurately as there were few years with a large response for any crop. However, the evidence is that the maximum response that could be expected for potatoes was 0·19 t/ha/mm water, and for grain dry matter of beans 0·006 t/ha/mm. The figure for potatoes agrees with that obtained by Penman at Woburn; the response of beans was much smaller at Rothamsted, partly because of severe attacks of broad bean stain virus.

Two experiments with growing pigs showed that the addition of L-lysine hydrochloride to diets limiting in lysine content raised not only N retention but also true N digestibility as a percentage of the diet. The change achieved in amino acid balance had no consistent effect upon ED (digestible energy, kJ/g diet) and therefore the experiment did not support the hypothesis that non-linear changes in dietary ED, resulting from ingredient substitutions, could be attributed to associated changes in amino acid balance.

Proximal colons taken from foetal and newly born lambs have been shown to actively transport methionine from lumen to blood when incubated under in vitroconditions. The lumen to blood flux of methionine, measured across foetal and early post-natal colons was approximately 25 and 15 times greater than the blood to lumen flux, each flux being determined in the presence of 1 mM methionine.

The ability of the colon to transport methionine decreased with age, there being no net transport across the colon of a 26-day-old lamb. The post-natal disappearance of this transport function appeared to be roughly exponential with a half-time of approximately 2 days.

The short-circuit currents and open-circuit voltages, measured across proximal colons of lambs of different ages, remained stable throughout incubation. The transtissue electrical resistance of colons taken from 9- and 16-day-old lambs was approximately double that recorded across colons taken from younger animals.

These results are discussed both in relation to what is already known concerning amino acid transport in the neonatal pig colon and in relation to what their possible physiological significance might be to normal post-natal development in lambs.

The body weight and fleece weight of Marwari and Magra sheep (rams) of the desert areas of north-western India are compared with those of Corriedale rams, which are being imported into India for improving the productivity of the local stock through cross-breeding. All three breeds showed marked seasonal fluctuation in their body weight. While the Corriedales lost more body weight than the indigenous breeds during peak summer, they appeared to endure the relatively poor winter pasture conditions somewhat better. Between July and October, with the availability of lush monsoonal pasture, all three breeds increased in body weight.

The greasy fleece weight of Corriedale rams was nearly double that of indigenous rams. The potential of the Corriedale ram for improving the productivity of the local stock is discussed.

FI (mg of fructose utilized by 109 sperms in 60 min at 37 °C), fructolytic coefficient, Ku (fractional decline in the spermatozoal fructolytic activity per minute on an instantaneous basis) and maximum fructose utilization, MFU (mg of fructose utilized by 109 sperms in 1 min at zero incubation time on an instantaneous basis), have been estimated for buffalo spermatozoa. Out of these three attributes, the fructolytic coefficient was found to be independent of the initial fructose concentration (IFC), sperm concentration and incubation period and was a better criterion for the assessment of the quality of buffalo semen than the fructolytic index.

Simple and partial correlation coefficients between sperm concentration, IFC and FI, fructolytic coefficient and maximum fructose utilization are presented.

The effects of nitrogen treatment on blade length and longevity were studied in primary growth of early and late varieties of perennial ryegrass, timothy and cocksfoot. Reproductive and vegetative tillers were examined in cocksfoot, but in perennial ryegrass and timothy the study was restricted to reproductive tillers, which accounted for a large proportion of the primary growth in these species. Results obtained by a technique which involved repeated recording of tillers were corroborated by those obtained by destructive sampling of tillers.

With respect to the blade length of culm leaves, responses to nitrogen shown by S. 23 ryegrass and S. 48 timothy were greater than those of the early-heading varieties S. 24 ryegrass and S. 352 timothy. However, blade longevity was appreciably reduced by nitrogen in the late varieties whereas the early varieties showed a much lower response.

Implications of these results in relation to the accumulation of senescing material in primary growth are discussed.

The pattern of leaf expansion in vegetative tillers of cocksfoot is discussed in relation to regrowth.

Soil air was sampled daily at depths of 5, 10, 20 and 30 cm in fallow and cropped plots, which had either been rolled or cultivated. Carbon dioxide was measured by gas chromatography.

Carbon dioxide concentrations were greater in the cropped than in the fallow plots. The rolled plots were wetter than the cultivated plots and carbon dioxide concentrations were also greater.

In the fallow plots, carbon dioxide was correlated with soil temperature but variations in soil moisture content had little immediate effect.

In the cropped plots, temperature effects were overshadowed by the response to irrigation which immediately increased the carbon dioxide concentration. These increases were attributed to enhanced root respiration, rather than to restricted diffusion or increased microbial activity.

An experiment was conducted at six widely separated centres in England and Wales for 4 years to compare the response of a perennial ryegrass (cv. S. 23) sward to fertilizer N at input rates of 200, 400 and 600 kg N/ha under cutting-only or grazing-only management systems. Under both managements the yield response to N varied substantially and was always greater under cutting than grazing and the response was greater in the first than in subsequent years. Under cutting, significant responses were obtained from 200 to 400 kg N/ha at all sites and in all years but very few sites responded significantly from 400 to 600 kg N/ha after the first year. Under grazing there was on average of all sites (but not at every site) a significant response from 200 to 400 kg N/ha only in the first year. In subsequent years no single site gave a worthwhile response in each year. Under grazing no site showed a significant response from 400 to 600 kg N/ha.

At the lowest application of nitrogen, 200 kg N/ha, dry-matter yields under grazing were greater than those under cutting on eight of the possible 24 centre-year occasions. At the two higher rates of applied nitrogen dry-matter yields under cutting were consistently greater than those under grazing.

With smaller responses to applied nitrogen on grazed than on cut swards maximum yields were achieved under grazing with an input of about 200 kg N/ha less than under cutting management. The results suggest that cutting experiments cannot be used to predict herbage yields and responses to fertilizer nitrogen under grazing conditions.

Studies on the effects of solvents on germinability of seeds of various crops established the optimum conditions for immersing seeds in several solvents. Reduction in germinability, in vitro and in soil, of seeds of cotton, bean, pea, soya bean, and sugar beet after immersion in acetone, dichloromethane, or ethanol for various periods up to 24 h depended upon the length of immersion and the seed type and solvent used. Soya-bean and sugar-beet seeds were the least sensitive to the solvents whereas bean and cotton seeds were the most sensitive. Various cultivars of the same crop behaved similarly. The amount of seed germination in vitro was similar to that in soil. Solvent combinations consisting of acetone with dimethylsulphoxide, dichloroethane. polyethylene glycol, or triethanolamine did not affect cotton-seed germination in soil whereas soya-bean seeds were adversely affected by some materials. The amount of solvent taken up by the seeds and the amount of oxidizable matter extracted by the solvent depended upon the solvent and the crop. Maximum absorption of solvent occurred within 1 h. The amount of oxidizable material diffusing from seeds immersed in solvents was not correlated with the amount of solvent uptake or extent of seed germination.

The relationship has been investigated between the yield of oil-seed rape (Brassica napus L.) plants and (a) the proportion of podless stalks, (b) the proportion of pods infested by seed weevil larvae and (c) the effect of removing a proportion of buds and pods. Plants compensated for damage and, although late removal of buds or pods sometimes caused greater yield loss than early removal, only plants with more than 60% podless stalks or buds removed had diminished yields. The numbers of podless stalks per plant increased with plant size. Removal of 60 % of a plant's pods caused no yield loss; in the field a maximum infestation of only 25% of the plant's pods with seed weevil larvae occurred. The results are discussed in relation to damage by pollen beetles (Meligethes aeneus Fab.) and seed weevils (Ceutorhynch.ua ossimilis Payk.)

Four young lambs fitted with cannulas at the pylorus and at the ileo-caecal junction were used to study the effects of weaning on digesta flow and mineral absorption. Prior to weaning when milk alone was fed the small intestine was the major site for dry matter disappearance and for the absorption of Ca, P, Na and K. Both the small and the large intestine were, however, important sites for Mg absorption at this time.

After weaning, when the lambs were fed a concentrate diet, at least two-thirds of the digested dry matter disappeared within the reticulo-rumen. The small intestine, however, still remained the major site for the absorption of Ca, P, Na and K. Most Mg absorption, in contrast, now occurred anterior to the pylorus and it would appear that the move from hindgut to foregut as a site for Mg absorption was directly associated with the introduction of dry feed and the development of fermentative digestion within the reticulo-rumen.

Both before and after weaning the faeces was the major route for the excretion of Ca surplus to requirement and the faeces also became increasingly important as a pathway for P and Mg excretion once dry feed was given. The urine, in contrast, was consistently the major pathway for the excretion of Na and K.

The variation in the sodium, potassium, calcium, magnesium, zinc, iron, manganese, copper, phosphorus and nitrogen concentrations in autumn regrowth herbage across a perennial ryegrass (Lolium perenne) pasture has been measured. The regrowth resulting from urine return by sheep to a pasture takes the form of an ‘island’ of herbage in which nitrogen (27%) and potassium (28%) are significantly higher than, and calcium (20%), magnesium (10%), phosphorus (24%), and manganese (40%) are significantly lower than in the surrounding herbage. Because of the selective grazing behaviour of sheep the possible implications for animal health of this pattern of element composition across a pasture are discussed.

Three groups (1, 2 and 3) of weaned Hereford steers were grazed separately on pasture. Groups 1 and 2 were supplemented with hay and oats during autumn and winter in an attempt to maintain two rates of live-weight gain, namely 0·8 and 0·4 kg/day, respectively. Group 3 was not supplemented and gained at zero and 0·11 kg/day during corresponding periods in the 2 years in which the experiment was repeated (years 1 and 2).

Supplementation ceased at the end of winter (September). Group 1 steers were slaughtered at the end of the growing season (January) when their mean live weight was 420 and 450 kg in years 1 and 2 at 19 months of age. Thereafter, groups 2 and 3 were removed from the plots and grazed together on another pasture at a reduced stocking rate until they attained the slaughter live weights of group 1 when they were slaughtered at 25 and 27 months of age, respectively.

Mean depth of fat cover over the eye muscle at the 10–11th rib in groups 1, 2 and 3 were 8, 6 and 4 mm in year 1, and 12, 5 and 6 mm in year 2, respectively. Group 1 carcasses had shorter skeletal dimensions, contained more fat and graded better than the carcasses of groups 2 and 3. The Longissimus dorsi muscles from group 1 were found to be the most tender in year 1 but no treatment effects were detected in year 2.