Brassica oil seeds grown in India are occasionally damaged by frost, causing severe losses. A technique was developed to screen germplasm at the seedling stage. Twentyfour lines of B. campestris, B. juncea and B. napus were grown in plastic boxes in a glasshouse in a mixture of peat and sand. The seedlings were frozen after hardening for 2 days at 1 °C. Observations were recorded after 4 days, using a five-point scale. Frost tolerance index (FI) is calculated as the average value for injured plants for each line. Eight lines for each of the three species were tested. B. campestrisas a group showed better frost tolerance. Some lines of Indian mustard also showed good tolerance of low temperature (– 5·5 °C). These findings show good agreement with observations recorded in the literature. The method is detailed and discussed. Suggestions for future programmes are made.

Field experiments were conducted on four barley cultivars (two hulled and two hullless) grown under unirrigated conditions in Varanasi, India, to observe the effect of rate of application of nitrogen on copper concentration and uptake in plants and soils. The copper concentration in both plants and soil decreased with age of crop because of the dilution effect of more vegetative growth. Varieties did not differ in copper concentration of plants but increasing application of nitrogen decreased copper concentration in the plants. Since the hulled varieties yielded more than the hull-less ones, they removed more copper from the soil. Similarly yield was increased linearly by the application of N fertilizer and this led to a linear increase in depletion of available copper.

Pigeon pea (variety Cita-1) was sown on ridges at two plantings in the early and late seasons of 1983 at the University of Ibadan, Two to three weeks after the plants reached maturity and the pods had been harvested by hand-picking, the plants were either ratooned by cutting off the tops at a height of 30 and 60 cm or left intact.

At the end of the first and second regrowths, the plants ratooned at 30 and 60 cm had performed better than those left intact in terms of growth and yield characters as well as seed yield. However, the plants ratooned at 30 cm performed best followed by those ratooned at 60 cm. The total seed yield from the planting was 3–6 times higher than if the crop had been harvested once.

It would seem that ratooning at 30 cm would give the highest returns from a single planting under the prevailing lowland tropical conditions.

The cellulolytic activity of cell-free extracts of 15 species of entodiniomorphid protozoa grown in vitro and under two conditions in vitrohas been measured using six different assays with substrates varying in complexity from carboxymethylcellulose to microcrystalline cellulose. Although there were differences between the assays, the highest activities were found in Eudiplodinium maggii, Epidinium ecaudatum caudatum and Ostracodinium obtusum bilobum with little or no activity in five Entodiniumspp. There was no consistent effect of growth conditions on cellulase content although with protozoa grown in vitro those grown on grass alone tended to contain more cellulase than those grown on starch and grass.

A survey of methods for the release of cellulase from other rumen fractions was made and mild treatment with ultrasound of the fraction suspended in water gave the maximal release of enzyme with the highest specific activity. Using this method 62% of the total rumen cellulase was found in the protozoal fraction and 27% was associated with the plant debris in a normal sheep, fed on hay and oats, with an A-type protozoal population.

Physical measurements were made on the soil of a long-term cultivation experiment comparing direct drilling, tine cultivation and mouldboard ploughing for spring barley to investigate possible reasons for differences in yield. The soil was a typical argillio brown earth, approximately 90 cm of sandy clay loam topsoil and clay loam subsoil overlying magnesian limestone. For the three periods 1971–4, 1975–7 and 1978–80 the mean grain yields were marginally lower after direct drilling than after shallow cultivation or ploughing. There was an average decline in yield of 1·33 t/ha from the first to the last period, the decline being greater for direct drilling than the other two tillage systems. Although the surface horizon (0–5 cm) of direct-drilled soil had a higher content of organic matter than the ploughed, this did not increase the stability of the aggregates. Slaking tests had shown the soil to be inherently unstable and likely to suffer from structural problems. After the first 3 years bulk density of direct-drilled soil (0–15 cm) increased markedly to ca. l·5 g/cm8 and then remained relatively stable. In the ploughed soil, density increased steadily over the period to an average value of co. 1·45 g/cm8. Tine cultivation to 7–8 cm reduced cone resistance values in the surface compared with direct-drilled soil but below 15 cm there were no significant differences. Ploughing gave significantly lower values than direct drilling to a depth of 30 cm. Measurements of pore sizes in direct-drilled and ploughed soil were highly variable with few significant differences. Mean air capacity values (1978–80) tended to be lower in direct-drilled than in ploughed topsoil particularly for plots direct drilled after 7 years of deep tine cultivation. A limited number of root measurements in 1978 and 1980 showed that the length of root per unit of ground area was much less after direct drilling than after ploughing. Shallow cultivation, surprisingly, gave most root with a greater proportion of the root system below 20 cm than in the other two treatments. The classification of this soil according to its suitability for direct drilling cereals is discussed.

Suckled single lambs, 6 weeks of age at slaughter, were used to study the melting point, iodine value, fatty acid composition and softness index of carcass fat. The lambs, born in mid-October in central Greece, were suckled from birth to slaughter and received no supplementary feed. They consisted of 43 Sarakatsaniko, 22 Karagouniko and 29 Chios x (East Friesland x Karagouniko). At slaughter, samples of subcutaneous fat from the base of the tail and perinephric fat were removed and stored at – 10 °C until analysed.

Melting point and iodine value were determined by the Association of Official Analytical Chemists (1980) and International Union of Pure and Applied Chemistry (1977) methods of analysis. Gas-liquid chromatography, on 12% diethyleneglycol succinate as stationary phase, was used for fatty acid methyl esters analysis. Softness index was calculated.

Component fatty acids in decreasing order of proportion in total fat were oleic, palmitic, stearic, myristic, palmitoleic, linoleic, linolenic, lauric and capric acids. The total of odd-numbered n-acids and branched chain acids occupied a position approximately mid-way. There was very little evidence of differences between the sexes. However, the differences between the two fat depots and those between breeds were significant in most of the traits. Significant correlations between some of the traits studied and also linear regression equations between selected variables were obtained.

Multi-factorial experiments on winter wheat cv. Hustler in autumn 1979 and 1980 sown on a clay loam soil following potatoes tested the effects of combinations of the following eight factors, each at two levels: sowing date; amount of nitrogen; division of nitrogen; timing of nitrogen; irrigation; autumn pesticide (aldicarb); summer aphicide (pirimicarb); and fungicide (carbendazim, tridemorph, maneb and captafol).

The mean grain yields of all plots in 1980 and 1981 were respectively 9·6 and 8·3 t/ha; the best eight-plot means were 11·2 and 9·9 t/ha. Fungicides had the largest effect on grain yield, increasing it by 0·8 and 1·7 t/ha in 1980 and 1981, mainly by increasing grain size. Effects were greater with earlier sowing and the larger amount of nitrogen. Benefits from fungicide were well related to the control of leaf diseases, mainly Septoria spp., which became severe after anthesis. Fungicide temporarily decreased the number of saprophytic fungi on the developing ears. Aphids that appeared in autumn on plots sown in mid-September were controlled by autumn pesticide, which also prevented the spread of barley yellow dwarf virus that occurred only in 1981. Consequently, yield of early-sown plots in 1981 was increased by autumn pesticide, but only when the severe infection with leaf diseases was controlled by fungicide. Autumn pesticide decreased nematode populations. Aphid populations in summer were small and yield was unaffected by the decrease in numbers that followed application of an aphicide.

Sowing on 20 or 15 September, as compared with 19 or 30 October, caused faster growth and development and greater uptake of N from the soil early in the season. Effects were smaller after April: earlier sowing increased total dry weight by 2·5–3·0 t/ha and, when leaf diseases and barley yellow dwarf virus were controlled, increased yield by 0·9-l·0t/ha. Increasing the amount of N applied by 70 kg/ha (from 105 or 80), increased yield only in 1980 and then only when fungicide was used. Extra N decreased yield in 1981 in the absence of fungicide. Extra N always increased N uptake and decreased grain size. Applying mostor all of the Non 4 or 19 March instead of 15 or 23 April resulted in less uptake of N from anthesis onwards and smaller yield, especially in 1980. N in three applications instead of one had negligible effect. Trickle irrigation decreased yield slightly, despite delaying leaf senescence and increasing straw weight. Attributes of wheat on best yielding plots differed little between years. Average values were: 534 ears/m2; 40·7 grains/ear; 40·4 mg/grain; 18·8 t/ha total dry matter and 214 kg N/ha uptake by grain plus straw.

Effects of seven levels of N application and three seeds mixtures were studied on two sites for 4 years. One seeds mixture comprised perennial ryegrass (Lolium perenne L.) and two comprised perennial ryegrass with white olover (Trifolium repens L.). One site (Trefloyne) was 24 m above sea level on deep soil and the other (Pwllpeiran) was 328 m above sea level on relatively shallow soil. The plots were cut seven times per year.

The application of N to swards without clover considerably increased the number of ryegrass tillers as well as increasing ryegrass leaf blade length and width and sheath length. At Trefloyne the presence of clover greatly reduced the number of ryegrass tillers, had a greater positive effect on grass sheath length, relative to its effect on blade length and width, than that obtained by applying fertilizer N to a sward without clover, and tended to reduce grass leaf length during the winter. At Pwllpeiran the clover was less competitive, but it still tended to have a greater effect on sheath length and a less positive effect on numbers of tillers, relative to its effect on blade length and width, than that obtained by applying fertilizer N to a sward without clover. The application of N to grassolover swards increased the size of grass leaves and the number of tillers, but did not increase clover leaflet size. The number of olover leaves in the sward was greatly reduced by fertilizer N at Pwllpeiran, but was not affected by fertilizer N at Trefloyne. Blanca white clover had larger leaves than Aberystwyth S.100, but S.100 appeared to compensate for this by producing rather more leaves. In respect of number of leaves, leaf dimensions and rate of leaf emergence, clover appeared more sensitive than ryegrass to the differences between the sites. The leaf dimensions of the clover varied more from one time of year to another, but not from one year to another, than those of the ryegrass. The number of leaves per unit area of ground varied more in clover than in grass from year to year and from one time of year to another. The rate of emergence of leaves was faster in clover (per marked stolon tip) than in grass (per tiller).

Digestibility trials were carried out with five individuals each of domesticated oryx, sheep and cattle, using three diets ranging from 12·5 to 7·4% crude protein. Feed intake, water consumption and urine production were measured.

Intakes of dry matter (as g/day or g/kg W0·75/day) did not differ between diets for any species. On a metabolic weight basis the sheep and oryx ate the same amount. The cattle ate more than the sheep of all three diets, and more than the oryx in two of the three.

For all three species, digestibility of dry matter, crude protein and crude fibre was lower when the lower quality food was given. On any single diet, significant differences in digestive efficiency for any diet component between species were few and small.

Total daily intakes of water (ml/kg W0·85/day) were lower for each species when eating the diet with the lowest protein content. On each diet total intakes were significantly different in the decreasing order cattle > sheep > oryx, in the mean ratio 3·3:l·7:10.

Urine production (ml/kg W0·85/day) varied slightly between diets for each species. On each diet the cattle produced significantly more urine than the sheep or oryx. The ratio of urine produced to water drunk decreased in the order oryx > cow > sheep, in the mean ratios 0·63, 0·34 and 0·27. Despite some interspecific differences in nitrogen concentration, there were few differences in the proportion of total excreted nitrogen that was lost through the urine.

Calculations of evaporative water loss showed that loss of water by this avenue was significantly less in oryx than in sheep or cattle, which did not differ significantly.

In the absence of any evidence of a more efficient digestion, the low metabolic intake of food by oryx suggests a low metabolic rate. The oryx's low water consumption and small evaporative loss are obvious adaptations to its desert habitat.

The results on the influence of various crops in five different fixed rotations on the ohanges in nitrate and total N content of soils are reported. Groundnut contributed largely to the accumulation of nitrate nitrogen in the soil profile (to a depth of 120 cm). Bajra fodder exhausted the soil nitrogen reserve to a great extent. Wheat and maize, in a rotation, reduced nitrate leaching to deeper soil layers. Summer moong also left a large amount of unabsorbed nitrate in the profile. Total nitrogen content of the soil decreased after the harvest of cereals. Maximum depletion occurred after the harvest of bajra crop. Potato (a crop which received a heavy dressing of N fertilizer) and legumes contributed to the soil N reserve. A balance sheet of N indicated net gains of total soil N in four of the five cropping sequences. A net loss of 75 kg N/ha was observed in bajra fodder-potato-wheat rotation.

The growth, development and grain yield of two low-tillering lines of wheat of Israeli origin were compared with those of two freely tillering Australian wheat cultivars (Gamenya and Egret) in field plots. The majority of individuals from the low-tillering selections were uniculms or biculms. Detailed observations were made on the main shoot of the biculms. There was no difference in the duration of primordia production by the main shoot apex between genotypes but the rate of initiation of spikelet primordia in the lowtillering lines was significantly greater than that of the tillering cultivars and this resulted in a large ear with more spikelets. The rate of leaf appearance was very similar in all genotypes but the later-appearing leaves of the biculms were very large in comparison with those of the cultivars. The majority of the biculms produced the tiller in T3 position. At maturity the main shoot and tiller of biculm individuals produced 60 and 40% respectively more dry weight than the equivalent shoots of the tillering cultivars. The total biomass per plant of the biculms was similar to that of Egret but less than that of Gamenya. The grain yield of the main shoot of the biculms was 50% greater than that for the tillering varieties and this was associated with an increase in the number of grains per ear as there was little difference in grain size. In the biculm a high proportion of the spikelets in the mid part of the main shoot ear produced five grains; grains from basal florets were significantly larger than those of upper florets mainly because they had a longer duration of growth. Overall the grain yield of the two tillering cultivars, either per plant or per metre of row length, was approximately 30% greater than that of the low-tillering selections. The greater growth of the main shoot axis in the biculms therefore did not compensate for the grain contributed by the tillers of the freely tillering cultivars.

Observations on oryx, sheep and cattle under natural grazing conditions in both a wet and a dry season are given and discussed.

Dry faecal outputs by the sheep and oryx were less in the wet than in the dry season. Output by the cattle was greater than both, and showed little seasonal difference. Faecal nitrogen concentrations showed no interspecific overlap, in the rank order sheep > oryx > cattle. All were greater in the wet season, and the rank order maintained.

Drinking water intakes were similar for oryx and sheep in both seasons. The cattle's water intake was greater in the wet season. Expressed as ml/kg W0·85/day, there were no overlaps in species' mean intakes, in the order cattle > sheep > oryx, in the ratio 100:57:24. In the dry season, the herd walked 16 km on non-drinking days, and a further 7 km on alternate days when receiving water. Under wetter conditions with more forage available, the herd walked only 11 km daily.

Slight interspecific differences in the times spent walking, feeding, standing and lying were found over a 48 h period. In the wet season less time was spent walking and feeding, with corresponding increases in the other activities. The oryx were notable in that rumination occupied far less of their daytime activity than for the sheep or cattle although the total times spent ruminating were similar.

The results are discussed in relation to differences in the species’ feeding habits and strategies of diet selection, combining the grazing results with observations from penned animals on a common diet. The intakes of water agree with the results from penned animals, confirming oryx's adaptation to hot, dry conditions. The advantages of a low water requirement, met by intermittent drinking, are discussed.

The possible detrimental effects on productivity of a regime of day-grazing and night-penning under hot conditions are discussed. In the light of these, some advantages to oryx of scheduling its rumination to the night hours are suggested.

A continuously grazed trial on natural and sown pastures under coconuts was reported by Watson & Whiteman (1981). This has been continued for another 3 years as a rotationally grazed trial. The paddocks were divided down the centre and three animals grazed for 28 days in one half and were transferred to the other half for 28days. The same three stocking rates of 1·5, 2·5 and 3·5 steers/ha were maintained. In the sown pasture paddocks Brachiaria decumbensand Brachiaria miliiformis were planted in rows from rooted cuttings, while Centrosema pubescens (centro) and Pueraria phaseoloides (puero) were sown, with seed at 4 and 3 kg/ha, respectively. Naturalized pastures were maintained by grazing at 2·5 steers/ha during the establishment of the sown pasture. Light transmission was 62 %. Sown grasses were lost after 4 months from the start of rotational grazing. In the sown pastures puero became dominant. Animal live-weight gain (LWG) on puero was poor in the first 140 days of grazing in each year, but after this time it increased. Centro was the dominant species in the natural pasture of 2·5 and 3·5 steers/ha. However, there was little difference in yearly LWG except in year 3 when the 2·5 steers/ha had higher gains in the natural (363 kg/ha) than in the sown pasture (250 kg/ha). Th9 mean live-weight gain (kg/ha) in the first 2 years of the rotationally grazed trial (315 kg/ha) was lower than in the continuously grazed trial (364 kg/ha) at 3·5 steers/ha. The time and efficiency of collecting fallen coconuts was lower at 1·5 steers/ha in both pastures, but not different between 2·5 and 3·5 steers/ha. In continuous and rotational grazing there is little point in planting Brachiaria species. Productive pastures in plantations oan be obtained by conti oiling weeds and sowing centro and puero into the naturalized Axonopus compressus and stocking at 2–5–3–0 steers/ha. Further research on other grasses such as Ischaemum aristatum and Stenotaphrumsecundatum may lead to better grass persistence.

Three experiments examined the effects of sowing rate and between-row spacing on the plant density and yield of red beet.

The proportion of seeds which produced mature plants decreased when the mean distance to the nearest neighbour was less than 5 cm. In these experiments, this distance was governed by within-row spacing. Thus, plots with narrow-spaced rows achieved a higher plant density than those with wide-spaced rows, when sown with the same weight of seed.

Total yield of beet per unit area decreased with increasing plant density. Maximum yields per unit area of small beet were achieved at high plant densities, whereas maximum yields of large beet were achieved at low plant densities. The effect of between-row spacing on yield was much smaller than that of density, and was important only for crops harvested early. Shoot yield per unit area was measured in two experiments and was not affected by row spacing in either. Shoot yield was not affected by plant density in one experiment, but, in the other, tended to a maximum value with increasing plant density.

Growth rates were compared of pigeonpea (Cajanus cajan), moth bean (Vigna aconitifolia), mung bean (Vigna radiata) and sorghum seedlings aged 2–5 weeks. The seedling growth rates were analysed in relation to leaf area development, net photosynthetic rate, nitrogen accumulation, nitrate reductase activity, and soluble protein content. Growth rates were highest in sorghum and lowest in C. cajan. Leaf area development was very fast in sorghum and very slow in C. cajan. Net photosynthetic rate of sorghum leaves was double that observed for the legume leaves. No significant difference was observed in nitrate reductase activity, nitrogen percentage or soluble protein content between sorghum and the legumes. In sorghum, early investment of assimilates into leaf development ensured a higher assimilation of carbon and nitrogen per plant. In the legumes, slow development of leaf area coupled with low photosynthetic rates probably resulted in slow growth of the seedlings. In the legume seedlings, vigour was related to the rates of leaf area expansion. Leaf area expansion rates were not related to the nitrogen status of the leaf in the species examined.

Pastures of a mixture of Brachiaria mutica(para) and B. decumbens(signal) grown with Gentrosema pubescens(centro) and Macroptilium atropurpureumcv. Siratro and grazed at three stocking rates 1·8, 2·1 and 3·6 animals/ha for 5 and 6 years of grazing were compared with B. humidicolacv. Tully (Koronivia) oversown with centro and siratro and grazed at 3·0, 3·6 and 4·5 animals/ha and native pastures of Themedaaustralis and Pennisetum polystachyon oversown with Stylosanthes guianensis cv. Schofield after burning, and grazed at 1·3, 2·0 and 2·7 animals/ha. All pastures were given 20 kg/ha of sulphur.

The para and centro pasture gave the highest live-weight gain with 731 kg/ha/year when stocked at 3·6 animals/ha in 1979–80. and 592 kg/ha/year in 1980–1. Signal grass gave 621 and 493 kg/ha/year in 1979–80 and 1980–1 at 3·6 animals/ha. Koronivia grass gave similar production as signal: 639, 466 and 406 kg/ha/year at 3·6 animals/ha stocking rate from 1979 to 1982. On the natural pastures 1st year gains were high, 412 kg/ha/year at 2·7 animals/ha, but declined to 224 kg/ha/year at 2·0 animals/ha in year 2.

In the para pastures, centro increased up to 50%, while with signal it increased to 25% of the botanical composition, owing to a decline in grass dry matter. In koronivia pastures, centro and siratro declined, inversely with stocking rate, and M.pudica increased in the high stocking rate. In the natural pastures T. triandra declined with increasing stocking, to 1% at 2·7 animals/ha. P. polystachyon remained approximately stable. M. pudica became important as grazing increased, and weeds also increased. Para grass was high in N, P, S and Na. N was low in signal, koronivia and T. triandra while the concentration of Na (0·41%) was high in koronivia, but it was extremely low in signal and T. triandra(0·02%).

The trials suggest that landholders could commence grazing of existing natural pastures for up to 2 years at about 2·0 animals/ha in the 1st year and 1·3 animals/ha in subsequent years to obtain 350 kg LWG/ha in year 1 and the 200 kg LWG/ha thereafter. With cultivated pastures much higher yield can be obtained using para plus centro on the low-lying aieas, and signal plus centro plus siratro on non-flooded areas. Koronivia can be used in occasionally intensively stocked areas. All pastures require S fertilizer every 2 years.

A number of commercial varieties and advanced breeding lines of wheat and of barley were each sown successively in the field from early in September until late in February in 3 or 2 years. Shoot apex development was monitored throughout the growing season and the dates at which the double ridge stage and the terminal spikelet stage were attained are reported. There was considerable variation in the date at which these stages occurred, associated both with variety and date of sowing. When sown early, spring wheat varieties and the winter wheat, Fenman, developed more rapidly than the other winter wheats, but the difference disappeared in sowings made in the middle of October or later. Spring barley developed more quickly than winter barley and the difference persisted until sowings made in mid-November.

Length of the longest leaf sheath, number of emerged leaves on the main shoot and the time when stem elongation began (‘ear at 1 cm’), plant characters used to assess the stage for various agronomic treatments, were measured in parallel with apex development. The relationships between number of emerged leaves and the length of the longest leaf sheath and stage of development were found to vary with sowing date. The stage ‘ear at 1 cm’ provided a good guide to shoot apex development. Stem length and number of elongated internodes varied with date of sowing. Some of the variation in number of emerged leaves at a given stage and in the final number of elongated internodes was found to be correlated with total number of leaves on the main shoot. The form of analysis used indicated that sowing date may have important effects, via its effect on the number of leaves on the main shoot, on the duration of ear growth in wheat and barley and on the duration of ear formation in barley.

As part of an ongoing investigation of ovine neuroendocrine mechanisms relating to photoperiod and eventually to wool growth, the diurnal variation of depilation force (an index of the strength of attachment of wool fibres to the skin of sheep) was investigated in Merino wethers and Border Leicester Merino ewes. Circadian rhythms were demonstrated in depilation force in both ewes and wethers. Further experiments were performed to investigate circadian endocrine rhythms which may have some bearing on the observed rhythm in depilation force. Circadian rhythms 180° out of phase with the depilation force rhythm were observed in plasma cortisol concentrations and in pineal serotonin N-acetyltransferase activities in Merino wethers.

The effects on emergence and growth of crisp lettuce seedlings as a result of sowing seeds at different depths and pressing them into the furrow bottom with a weighted seed press wheel were examined in three similar experiments in 1982, 1983 and 1984. Sowing depth had a considerable effect on percentage seedling emergence and the spread of emergence times but the pattern of response varied from year to year and appeared to be related to differences in soil moisture content. The most uniform emergence and the highest level of emergence were achieved by sowing shallowly (< 10 mm) with rainfall almost immediately after sowing then keeping the soil moisture content close to field capacity for 2 days. When rainfall or irrigation were delayed, drilling 15–20 mm deep gave more consistent results. Effects on seedling weight and variability of weight were associated with the time and uniformity of seedling emergence. Later emerging seedlings were lighter and a wide spread of emergence times gave seedlings of variable weight. There was virtually no effect on emergence of using additional weights on a seed press wheel.

Stylosanthes humilis cv. Lawson, S. hamatacv. Verano, S. guianensis cv. Endeavour and Macroptilium atropurpureum cv. Siratro were oversown into native grassland dominated by Arundinaria ciliata and grazed by cattle at 2·5, 3·5, 4·5, 5·5 and 6·5 animal units/ha per half-year during the wet season for 4 years.

Siratro was the most persistent of the legumes but its susceptibility to heavy grazing pressure limited its contribution at the higher stocking rates. At the start of grazing its mean yield was 1420 kg/ha representing 40 % of total pasture yield while at the end of 4 years in the lowest stocking rate treatment it comprised 18% of total yield at 460 kg/ha.

The long-term productivity of the three Stylosanthes species was poor and their percentage contribution to the pastures was either zero or very low by the end of 4 years. Yield of Verano, the most successful of the three, declined from 5000 kg/ha in 1977 to 20 kg/ha in 1980. The main factor contributing to the poor performance of these species was the strongly competitive nature of A. ciliata. Percentage composition, height and yield of this tall, rhizomatous grass increased with time independent of stocking rate, and the illuminance of the Verano canopy was reduced to 0·38–0·65 full sunlight. Cattle showed negative selection for bamboo grass and consumed leaf but not stem; leaf to stem ratio was negatively (and unusually) related to stocking rate.

Stocking rate effects were reduced by the intervening dry season resting periods and the over-riding influence of other factors such as the prevailing climatic conditions, disease occurrence and plant interference.