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.

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.

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.

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.

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 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.

Regression models were constructed to predict the yields and digestibilities of herbage cut in different sequences of harvests.

The yield model used a seasonal production curve modified by the effects of defoliation. Values for the model parameters were obtained by fitting the model to experimental data using a non-linear regression procedure. When these parameters were used, to predict treatment effects in another series of experimental data, good agreement was obtained. The digestibility model incorporated the effect on digestibility time of year, regrowth time and yield.

Using the models to interpolate between the results of cutting experiments, annual yields were shown to increase with the date of first cut and also with the interval between subsequent cuts, whereas the average digestibility of the harvested material ecreased with the date of first cut and with the subsequent cutting interval. Finally, a procedure was devised for combining the two models in order to find an optimum cutting strategy for a hypothetical animal production system.

A general equation for predicting the movement of interacting and non-interacting solutes is proposed. Equations to predict the leaching fractions and mean displacement depth of linearly adsorbed solutes have been derived from the solution of the general equation. A simple equation which considerably reduces the experimental and analytical work has also been derived to evaluate the adsorption coefficient. The predicted adsorption coefficient compares favourably with published data.

The concentrations of dry matter, crude protein, fat and ash and of Ca, P, Mg, Na and K were determined for 22 sets of twin foetuses, 33 of triplets and 11 of quadruplets of known gestational ages within the range 55–145 days. In addition, determinations were made of the concentrations of dry matter, crude protein, fat and ash in their associated placentae and empty uteri, and of dry matter, nitrogen, energy and ash in the foetal fluids. The dry matter, crude protein and fat concentrations in the placentae increased with foetal age and decreased with increasing litter size. Ash concentrations were unaltered. There was no effect of litter size or foetal age on the concentration of nutrients in the empty uteri. Dry matter and nitrogen concentrations in the fluids increased with foetal age but were independent of litter size, whereas ash concentrations increased with litter size but not with age.

The form of the mathematical model for foetal growth is considered in relation to the estimation of rates of accretion and the estimation of the differences in composition to be expected between foetuses that are heavy and others that are light relative to their age. When the weights of the foetal constituents were fitted by Gompertz equations extended to include foetal weight as an allometric term, the effects of litter size on foetal composition could be estimated from the foetal weights for each size of litter. Concentrations of dry matter and of most constituents in the foetuses became less as numbers of foetuses increased, irrespective of stage of gestation.

A description of the changing composition of the growing foetuses was provided by specific growth rates calculated from the fitted equations. With minor exceptions, derived estimates of foetal concentrations of each constituent were found to agree quite well with most previously published estimates for ovine foetuses, but similar agreement on daily accretion rates was not to be expected in view of the sensitivity of such estimates to the choice of model for foetal growth. Rates of accretion in the gravid uterus increased up to about 5 weeks before parturition and tended to level off thereafter, but most of them still increased slightly over the last 2 weeks, even in ewes bearing triplets or quadruplets. Taking account of the changes in the maternal body of the ewes, it was concluded that although the prolific ewes incurred a substantial energy deficit, and could not have consumed sufficient of the diet to avoid this, their intakes in late pregnancy were nevertheless adequate to support the high rates of accretion of protein and of minerals in the gravid uterus.

The extents and sites of digestion of organic matter (OM), and its constituent watersoluble carbohydrates, organic acids, pectin, cellulose, hemicellulose and crude protein have been studied in sheep prepared with re-entrant duodenal cannulas and fed four fresh herbage diets, Ruanui perennial ryegrass, Tama Westerwolds ryegrass, Pitau white clover and Fakir sainfoin, at each of two levels of intake.

The water-soluble carbohydrate, organic acids and pectin of all diets were almost completely digested within the rumen. Some 10% of water soluble carbohydrate reached the duodenum on each diet, though this may not have been of dietary origin. Only on legume diets, where pectin concentration was higher, did measurable amounts of pectin reach the intestine, accounting for some 5% of the pectin.

Hemicellulose and cellulose digestibilities differed between diets, being lowest for sainfoin, and next lowest for clover. Between 79 and 94% of digestible hemicellulose was digested in the stomach, but diet and intake had no significant effect on this partition. Of the digestible cellulose, 87–97% was digested in the stomach.

Digestibility of N was lowest for sainfoin and highest for Tama ryegrass. There were no significant differences between herbage species or intake in the percentage of digested N digested in the stomach or intestines. The tannin contained in sainfoin had no effect on nitrogen digestion.

Data from this and other studies reported in the literature were examined as a basis for establishing prediction equations whereby the partition of digestion of the major carbohydrate and nitrogenous constituents in stomach and intestines might be estimated from data obtainable from standard digestibility trials. Regressions were developed for predicting the amounts of OM, cellulose, and hemicellulose digested in the stomach. There are not yet enough suitable data available to predict the amount of nitrogen entering the small intestine.

In summer 1977 a random survey was made of 2250 fields on 1153 farms selected throughout the United Kingdom. Wild oat, Avena spp., was surveyed in all countries; black grass, Alopecurus myosuroides, was surveyed in England and Wales; and couch grass, including Agropyron repens and other perennial grasses, in Scotland and N. Ireland.

Wild oat was reported by farmers on 95% of farms in England, 34% in Wales, 65% in Scotland and 30% in N. Ireland; the areas of infestation in the different countries were 67, 13, 37 and 16% respectively. The majority of wild oat was A.fatua. Only 6% of the cereal area of U.K., including sprayed and unsprayed fields, contained more than one wild oat seed head/m2 (10000/ha), the majority had less than one/20 m2. Black grass was reported on 50% of farms in England (22% of cereal area) mainly in East and South, and on 2% of farms in Wales. Couch grass occurred on 92% of farms in Scotland and 68% in N. Ireland: areas of infestation were 88 and 67% respectively. Most of the infestations of all three weeds had been present for longer than 5 years.

Most farmers intended to eliminate or reduce wild oat and few proposed to hold the weed at its present level or do nothing. Herbicides were used against wild oat on approximately half of the infested area in England and Wales, with proportionately more use in Wales and much less in Scotland and N. Ireland. A third of the black grass infested area of England was treated with a herbicide. There was little spraying against couch grass in Scotland and N. Ireland. Details of dose, time of application and mixing of chemicals were obtained. Wild oat was subsequently found on most of the area treated against this weed, similar observations were made of black grass and couch grass. Most farmers considered herbicide performance good or excellent and those in East and South England believed wild oat to be decreasing as a problem; farmers elsewhere thought the problem to be increasing.

Hand pulling of wild oat (roguing) had occurred on only one tenth of the infested area but a greater area was intended to be rogued after the survey visit. Much of the land that had been rogued was found subsequently to contain few wild oats.

The survey provided information on associations between weed presence, soil type and cropping system, the types of herbicide used and farmers’ impressions of their performance. Comparisons are made with previous surveys in 1972, and information on the disposal of the 1976 crop of straw and on types of cultivation used in different regions is provided. The implications of the results are discussed.

In three experiments the effects of amount and source of nitrogen and energy supplements, and their frequency of feeding, on the voluntary intake and digestion of winter-quality freeze-stored heather (digestibility of organic matter 45%, N content 1·3%) by Scottish Blackface castrated male sheep were examined. The continuous infusion of 0·5gN/day as urea or casein increased voluntary intake by 29% and digestibility of organic matter by 11 percentage units but higher amounts of N supplement gave no further responses. The continuous infusion of a supplement containing 100 g sucrose/day and 3 g N/day as urea gave similar responses in voluntary intake and digestibility of heather to those obtained when N alone was infused. A reduction in the frequency of feeding of the sucrose: urea supplement reduced the response in intake of digestible OM of heather but intakes of digestible OM were higher when an isocaloric supplement of starch: urea was given at the same frequencies (thrice and once daily). The results are discussed in relation to the use of ruminal NH3 concentrations to assess the responses in voluntary intake to N supplementation and the balance required between the nitrogen and energy in the supplement. I t is concluded that the nitrogen and energy supplements could improve the nutrition of sheep grazing heather moorland in winter.

A number of experiments to test the effects of N and P fertilizers and a few testing K fertilizer were carried out mainly with Arran Banner and Up-to-Date potatoes in the major potato-growing area of Cyprus (Kokkinoohoria). The optimum nitrogen rate, all applied at planting in January-February, was 60–120 kg N/ha with yields reaching 50 t/ha. Phosphorus increased yields in only 4 out of 21 trials. In two of these cases the soil contained 8 mg bicarbonate-extractable P/kg soil or less. In the other two cases the soil contained 34 and 56 mg P/kg but irrigation was erratic. In only one experiment where soil potassium was depleted to 222 mg exchangeable K/kg through continuous cropping with irrigated crops, without potassium fertilizer, was a clear response to K fertilizer obtained; this, however, is the first response to K fertilizer by any crop reported in a plain area of Cyprus.

Concentration of NO2·N in the petiole of the first mature leaf from the top sampled at 80 days from planting under the 120 kg N/ha rate, beyond which seldom were yields increased, was about 0·5%. In the only experiment where a response to K was obtained, concentration of K in entire leaves sampled as above was about 2·5%.

It is argued that since growers in this area have used heavy dressings of P and K over recent years, they will seldom get any benefit from applying more than a maintenance dose of 70 kg P and 150 kg K/ha to the potato crop. It is suggested that since in semiarid regions leaching is limited, soil tests of NO3 content can aid farmers in choosing the optimum amount of N fertilizer for each crop.

Equations to predict the leached fractions of initially surface-applied salts either with irrigation water or broadcast on the soil surface have been derived from the solution of the dispersion-convection equation. Predictions obtained from these equations compare well with observed leaching data of chlorides and nitrates. It is shown that the loss of fertilizers when applied with irrigation water is reduced compared with that of applying it by broadcasting. The use of equations for predicting soil salinization and leaching of surface-concentrated salts is also indicated.

An investigation was carried out into the potential of tylosin and terramycin fermentation wastes as fertilizers for tomatoes. Each waste was added at concentrations equivalent to 1 tN/ha to John Innes base compost. Each waste provided the sole source of nitrogen for the crop. Controls were set up with inorganic nitrogen applied at 1 tN/ha and 0·2 tN/ha, the quantity of nitrogen normally found in John Innes potting compost. Comparisons were also made between wet and dry terramycin waste. Each treatment was added to normal John Innes base compost and John Innes base minus one part peat, to determine the potential of antibiotic fermentation waste as a peat substitute. The size, weight and antibiotic content of the tomatoes produced were determined.

The use of antibiotic fermentation wastes delayed the onset of tomato production due to the slow release of nitrogen. Final yields were not significantly different from the control treatments except in the tylosin treatment which produced the highest yield, both in terms of weight and numbers, of all the treatments. The reduction in the amount of peat in the base compost only appeared to affect the control treatments, where a delay in the onset of tomato production was seen in the control low in peat. No antibiotic was detected in any of the tomatoes.

Data were collected from 218 commercial crops of vining peas (Pisum sativumcv. Dark Skinned Perfection) to test the hypothesis that variability between commercial crops in the yield of vining peas is associated with variation in the number of pods per plant. Yield varied widely between crops; the coefficient of variation of crop yield adjusted to tenderometer reading 105 was 25%. Only a small part of this variation could be accounted for by the correlation between yield and the estimated number of pods per plant (r = 0·067, 216 D.F.), and significance levels were not substantially improved by allowing for the effects of sowing date and plant density, or by using data on number of pods at each separate node in place of the overall totals per plant. Consequently the hypothesis stated above is not supported and it is suggested that variation in the weight of peas per pod was the main cause of variation in yield between crops.

A number of significant relationships were noted in the correlation analyses; (1) the mean number of pods per node at adjacent nodes tended to be positively correlated; (2) the number of pods per node at the first podding node tended to be positively correlated with plant density; (3) the numbers at the upper nodes tended to be negatively correlated with sowing date and with harvest date.

An experiment was carried out to study the composition of the mixture of rumen short-chain fatty acids and the clearance rate of the rumen liquid phase in sheep given diets of dried grass, high-nitrogen hay, low-nitrogen hay and barley straw. Differences between diets in clearance rate were not significant (P > 0·05) and differences between diets in the composition of the mixture of rumen acids were small. There were substantial variations in clearance rate between individual sheep but this was not associated with variations in the pattern of fermentation and the correlation between the proportion of propionic acid and the clearance rate in the rumen was low (r = –0·23).

In a second experiment sheep receiving a moderate-quality hay were given intravenous injections of atropine sulphate which resulted in significant increases in rumen volume (P < 0·01) and significant reductions in ruminal clearance rate (P < 0·05). These were accompanied by significant increases in the numbers of protozoa (P < 0·05) and bacteria (P < 0·05) in the rumen but the composition of the mixture of rumen short-chain fatty acids was unchanged.

It is concluded that there is little possibility through alteration of ruminal clearance rate, for manipulation of rumen fermentation pattern in sheep receiving diets of moderate- or poor-quality forages.

Continuous observations were maintained on a group of 32 White Fulani (Bunaji) heifers at three periods daily, 06.00–12.00 h, 14.00–18.00 h and 18.00–22.00 h, for 112 days, during which time all heifers were recorded for incidence of standing for mounts for a while by a vasectomized bull but for the whole period by other heifers in the group as well as soliciting for mounts. Thirty heifers were judged as showing oestrus. Of the 62 oestrous cycles recorded, 82·2% had mean length (±S.E.) of 22·4 ± 0·7 days. Average duration of oestrus (±S. E.) in 30 heifers was 3·1±0·2 h. There were no significant differences between the three observation periods for the time spent in mounting activities, the duration cf oestrus commenced at the three periods and for the average oestrous periods.

It would appear that closer observation for indicative oestrus between 06.00 and 18.00 h should be valuable for the purpose of oestrus detection in an artificial insemination scheme under the Guinea Savanna condition of Nigeria.

A small-plot experiment on sandy loam soil at Woburn tested the effects of subsoiling by hand and of incorporating a large dressing of P and K fertilizer into the subsoil.

Ths treatments were applied once in 1973 and their effects were assessed from 1974 to 1977 on the yields of, and N, P, K uptakes by, barley, potatoes, wheat and sugar beet grown in rotation. All crops were present each year and all plots received annual seedbed dressings of N, P and K appropriate to the crop. Dolomitic limestone was applied once in the rotation. The effects of the treatments on P soluble in 0·5 M-NaHCO3 and exchangeable K in surface and subsoils were measured.

Subsoiling alone increased the 4-year mean yield of wheat by 21%, of barley by 24% and of sugar from sugar beet by 11%. Mean yield of potatoes was unaffected.

Incorporating P and K into the subsoil increased the mean yield of potatoes by 16% and further increased mean yield, in addition to the effect of subsoiling, of barley by 20% and of sugar by 4%. Mean yield of wheat was not further affected.