The paper gives an account of the results obtained from the data provided by the first three years of the Sampling Observations on Wheat of the Crop-Weather Scheme.

Section I describes the Sampling Observations on Wheat of the Crop Weather Scheme which have been initiated in order that the effect of weather conditions may be studied at all stages of the wheat crop’s growth from germination to maturity.

In Section II several curves are given which illustrate the progress of the wheat crop. The shoot-number curves bear a marked resemblance to one another subsequent to the period when the shoot number is a maximum in spite of the wide divergences which exist between the maximum shoot numbers themselves.

Section III indicates the statistical processes involved in the analyses given in the succeeding sections.

Sections IV-VIII are devoted primarily to discussions of the effects of various meteorological factors on specific stages of the crop’s growth. The following results have emerged:

The length of the interval from sowing to appearance above ground is shown to be largely dependent on the mean soil temperature during this interval, the relation being well expressed by a quadratic regression. The growth rates of the plants at this time are shown to be in good agreement with those which would be obtained by applying Van ‘t Hoff’s law. Neither the rainfall nor the variation in temperature during the period appear to affect its length.

Squarehead’s Master appears above ground consistently later than Yeoman, but the amount of this lag is apparently uninfluenced by variations in soil temperature.

Two field experiments were conducted in 1971–72 and 1972–73 on two similar sites of calcareous clay soils (vertisol) with paste pH 8·2, 0·024% and 0·22% organic carbon. Wheat (Triticum aestivum L. var. (LR N10) An3) was grown and the fertilizers ammonium sulphate, urea, nitrophoska 15% N, 15% P2O5, 6% K2O), calcium nitrate (Ca NO3)2·4H2O) and ammonium sulphate nitrate were each used at 70 kg N/ha at seeding, tillering, jointing or ear emergence and there was one treatment with no N fertilizer. The treatments were arranged in a randomized block design with four replications. Each plot was 6·0 x 7·0 m of which 4·0 x 5·0 m was harvested. N fertilizers were broadcast by hand and no basal potassium or phosphorus were added since they are known to have no effect on wheat yield on these soils. Seed a rate equivalent to 85 kg/ha was weighed separately for each plot and sown by hand in rows spaced 20 cm apart. Each experiment received 10 irrigations, each equivalent to a head of 10 cm of water, at 10-day intervals.

The leaf growth, carrying capacity and dairy production of four summer-growing pastures were measured in a subtropical area of Australia. The growing season was subdivided into ten 4-week periods and the production was estimated for each period. Carrying capacities were determined by rotationally grazing four paddocks of each pasture over the 4-week period, and varying the stocking density so that a target weight of leaf material remained on the pasture at the conclusion of each grazing.

A non-limiting rate of nitrogen fertilizer increased total leaf production of kikuyu by 97% over a control treatment without nitrogen, but the response was not evenly distributed throughout the season. It fell to 50% during autumn when growth on the nitrogen-fertilized pastures was restricted following heavy defoliation during late summer. The use of the tropical legumes, siratro and glycine, in a mixed sward with kikuyu, did not increase leaf production over a kikuyu control pasture. The legumes grew poorly and this appeared to be due to the combined effects of their poor adaptability to the krasnozem soil, a high plant mortality especially during the first winter after sowing, the 4-week grazing interval and strong grass competition.

The carrying capacity of the nitrogen-fertilized pasture was 1·3–5·3 cows/ha at the beginning (September–October) and end (April–mid June) of the growing season, and increased to a peak of 7·4–9·7 cows/ha during February-mid March. Nitrogen fertilizer increased the carrying capacity by an average of 131% over that on a kikuyu pasture without nitrogen. The carrying capacities were similar on kikuyu and on a mixed carpet grass-kikuyu pasture, both without nitrogen, but were less on a tropical legume-kikuyu pasture which was grazed at a lighter grazing intensity during autumn to aid legume persistence.

Reflecting the experimental method of adjusting the stocking density according to the pasture available, differences in dairy production per cow were small relative to differences in the carrying capacity. Consequently seasonal variation in total dairy production/ha mirrored the carrying capacity. Nitrogen fertilizer increased the average production of 4% fat-corrected milk to 13·2 t/ha/40 weeks, an increase of 133% over the control without nitrogen.

The results illustrate the marked seasonal imbalance in growth and carrying capacity for a given pasture, and emphasize the need to use mixed feeding systems to provide a uniform level of nutrition for a fixed number of cows.

The control of eyespot (Pseudocercosporella herpotrichoides (Fron) Deighton) is most effective after application of carbendazim (Hampel & Lücher, 1973; Taylor & Waterhouse, 1975) or prochloraz (Marshall & Ayres, 1986) at growth stages (GS) 30–31 (Zadoks, Chang & Konzak, 1974), although some control occurred after applying prochloraz with carbendazim at GS 37–49 (Marshall & Ayres, 1986). Growers in the U.K. are advised to apply eyespot fungicides only when severe disease is expected. This forecast is usually made at GS 30, and spraying is recommended when two or more leaf sheaths have been penetrated on at least 20% of shoots (Anon. 1985). However, subsequent weather conditions may result in severe eyespot developing when no spray was recommended, or may not favour eyespot and result in fungicide being wasted.

The biological and useful yield of Phaseolus vulgariscv. ‘Banja’ and cv. ‘Diacol Nima’ were compared when sown at populations, in row spacings, equivalent to 5–4–32–3 plants m~2, at four levels of fertility achieved by the use of zero, five, ten and 20 cwt ae-1 respectively of a fertilizer mixture containing by weight 2:2:1 calcium ammonium nitrate, single superphosphate and muriate of potash. Yield and its components were determined at final harvest. The two cultivars behaved generally similarly. Crop Index, while highest in the plants with no fertilizer, was more or less constant for each cultivar over a wide range of biological yields in those plants receiving fertilizer. Yield is determined to the extent of 85–7% and 86–1% respectively for 'Diacol Nima’ and ‘Banja’ by the product of pods/plant and plants surviving to harvest. High densities, although giving the highest grain yields, are wasteful of seed in that the percentage of plants surviving to contribute to yield is much reduced.

The interaction between Phytophthora infestans and potato viruses X (PVX) and Y (PVY) was studied in the potato cultivar Kufri Chandramukhi. Prior infection by PVX and PVY reduced the susceptibility of the plants to P. infestans. The reduction in susceptibility was more marked when leaflets were inoculated with P. infestans 72 h after inoculation with PVY. The same type of reaction was observed in whole plants when the interval between PVY and P. infestans inoculation was 30 days. No significant differences were observed when the sequence of inoculation was reversed.

The results obtained for the digestibility of the carbohydrates with 116 different rations fed to 242 non-pregnant dry cows and 96 lactating cows were studied.

Except for some roughages, reducing sugars, non-reducing sugars, and starch digestibility is always very high. Reducing-sugars digestibility is related to starch content and starch digestibility to crude-fibre content.

Pentosans and crude-fibre digestibility is related to dry-matter intake and to starch, pentosans and crude-fibre content. When the ration contains less than 12% protein, a significant correlation coefficient also exists between crude-fibre digestibility and protein content. But pentosans and crude-fibre digestibility depends above all on the nature of the feeds and on the stage of maturity of the forage.

The difficulties in the semi-arid regions of East Africa where cattle exist during the dry season on forage with a very low nitrogen content is discussed

An assessment was made of the relative merits in the short term of KH2PO4and pig slurry as sources of orthophosphate. This involved a comparison of these two sources of P with regard to (1) adsorption of P by the soil from solution, (2) maintenance of the solid-phase P in labile form and (3) rate of release of the solid-phase P into solution.

The adsorption isotherms made with two soils revealed that the amount of orthophosphate adsorbed from pig slurry was much higher than that from KH2PO4 at all levels of application. Conversely, in order to raise the orthophosphate concentration in the soil solution to a given level, much larger applications of orthophosphate would be required as pig slurry than that in the form of KH2PO4. Therefore, the risk of direct orthophosphate-P pollution of ground water from pig slurry is likely to be even less than that from soluble P fertilizers.

Determinations of exchangeable-P in treated soils after different times from treatment showed that a larger fraction of the solid-phase P derived from slurry orthophosphate remains in an exchangeable form than that from KH2PO4.

The rate of desorption of solid-phase P into solution measured using an anion exchange resin was higher in the KH2PO4-treated soil than that in the slurry-treated soil at different times from addition of equal amounts of orthophosphate-P.

1. The percentage of intramuscular fat (and its iodine number), of moisture (fat-free), and of total, myofibrillar, sarcoplasmic, stroma and non-protein nitrogens in lumbar 1. dorsi muscles, and their ultimate pH, fibre diameter, cross-sectional area and weight (both absolutely and as a percentage of the total musculature) were determined at bacon weight in two male and two female litter-mate pigs from each of four pure-bred sows mated with one boar of the same breed. Such data were obtained for pigs of Large White, Landrace and Welsh breeds.

1. The differences between strains in respect of tripping, pollination, self- and cross-fertilization, the number of pods and seeds set under comparable conditions, and the influence of weather and insects on these aspects was investigated during 1953–5 at Cambridge. Early, mid-season and late strains of lucerne were included in the experiments.

2. Early strains under natural conditions had a significantly higher percentage of florets tripped, and pods formed, than mid-season or late strains. The ease with which early strains tripped, and the likelihood that biological characters of their flowers were better adapted to environmental conditions, are possible reasons for their high percentage of pods set.

3. Tripping is essential for seed setting; at least 98·5% of pods resulted from florets tripped by insects or automatically.

4. There was little difference between strains in the percentage of self-fertilized florets, although in the early strains there was a slightly higher percentage, as well as a higher number of selffertilized plants. There was little difference between strains in the average number of seeds set per pod which was about 1·9 for artificial tripping and selfing and 1·5 for selfing under continuous cover. Under natural conditions, the estimated proportion of pods formed due to selfing was 20% in Eynsford and Du Puits, 12% in Provence and 16% in Grimm. The difference between strains in the percentage of pods formed by artificial crossing was small. The average number of seeds set per pod was 3·9 under natural conditions and 6·7 under artificial crossing for all strains.

5. Sunshine and high temperature encouraged tripping while rainfall suppressed tripping and pod setting. When the effect of temperature and rainfall were eliminated, duration of sunshine was the most important factor influencing tripping. Some variations in tripping and pod setting were found among plants of all strains in different seasons.

6. The population of wild bees was very low. Honeybees and other small insects caused some accidental tripping and crossing, especially in early strains.

Ninety triple test cross (TTC) families and 32 varieties of spring wheat (used as parents in TTC programme) were raised in three randomized blocks in 1977–8 and 1978–9 to detect additive, dominance and epistatic components of genetic variation and genotype x environment interaction at both micro- and macro-environmental levels for five quantitative traits: final plant height, spike length, number of spikelets per spike, 100-kernel weight and grain yield per plant. Epistasis was an important element for yield per plant in both years. But, absence of significant epistasis was observed for two component traits of yield, namely, spike length and number of spikelets per spike, in these 2 years. Dominance was directional in all cases. Additive gene effects were most sensitive to micro- as well as to macro-environmental differences.

Field work on rainfed cowpea (Vigna unguiculata (L.) Walp. cvs TC-9-6 and M-28-6-6) was conducted in the Orinoco lowlands to explain the changes in dry-mass partitioning and radiation-use efficiency (RUE) as compared with other cultivars over four consecutive seasons. Growth features were assessed in early-maturing, prostrate-canopy (TC-9-6), and medium-maturing, erect-canopy (M-28-6-6) cowpeas. These cultivars were sown in consecutive middle-wet and late-wet seasons in double peak rainfall conditions. Dry mass accumulation by cultivars was assessed as a function of leaf-area duration and the efficiency with which radiation was converted into dry mass throughout the season (i.e. radiation-use efficiency). Cultivar differences in canopy architecture and duration of leaf area had a minor effect on the total dry mass production. In the early-maturing TC-9-6, RUE for a middle-wet and a late-wet season was 0·90±0·04 and 0·65±0·05 g/MJ, respectively. In the medium-maturing M-28-6-6, the values were 0·97±0·05 and 0·72±0·03 g/MJ, respectively. A season with rainfall below 100 mm had a negative effect on phenology and RUE. When average rainfall was above 100 mm, the total dry mass accumulation was not affected by differences in cultivars and seasons. The rate of harvest index (HI) changes was negatively related to pod-filling duration. The changes in assimilation distribution depended on the process of partitioning as modulated by the limited pod-sink and the photosynthate supply. However, the photosynthate source was not depressed by the sink activity of the pod-filling. Partitioning to non-reproductive sinks was maintained. M-28-6-6 with high dry-mass production and delayed senescence did not effectively divert a large amount of assimilate to pod-filling. Pod sink activity in cowpea was limited by genotype. Harvest index in M-28-6-6 decreased with the increasing dry mass. The final HI and rate of linear increase in HI differed between cultivars and were lower in M-28-6-6. The results of the present work in the Orinoco lowlands are relevant for a wide range of savannahs with a late wet season.

Experiments on a sandy loam, using adequate fertilizer, gave:

(a) Crop yield (as total dry matter) when soil water content was kept near field capacity.

(b) A measure of the departure from field capacity (limiting deficit, Dι) that produced no detectable change in yield.

(c) Responses to irrigation: (i) conventional, as δY/δI; (ii) a theoretical maximum, k, after allowing for Dι in the water balance.

(d) Other information, botanical and technical.

Grass (S 22 Italian ryegrass)

Two year crop, cut fourteen times, October 1959 to October 1961.

(a) Best yields: 1960, 15 t ha−1 (ɛ ≃ 100 × 10−4); 1961, 12 t ha−1 (ɛ ≃ 70 × 10−4).

(b) Dι ≃ 5 cm.

(c) (i) δY/δI: 1960, 0·36; 1961, 0·43 t ha−1 cm−1; (iii) k: 1960, 0·40; 1961, 0·27 t ha−1 cm−1.

(d) In 1960 irrigation was needed in spring only: the benefit was maintained on plots with large N and K dressings, but almost disappeared on those with small dressings (Y = 11 t ha−1). In 1961 the unirrigated crop could not exploit all the limited summer rain: hence δY/δI > k.

One year crop, cut five times, March to October 1965.

(a) Yield, 12 t ha−1 (ɛ ≃ 90 × 10−4, from emergence).

(b) and (c) (i) The meteorological need was slight, Dι (above) was not exceeded, and there was no response; (c) (ii) k = 0·46 t ha−1 cm−1.

Lucerne (Du Puits)

Three year crop, cut eleven times, April 1962 to November 1964.

(a) Best yields: 1962, 7; 1963, 8; 1964, 10 t ha−1.

(b) Dι = 11 cm for established crop.

(c) (i) No response other than in first dry spring of establishment. At first cut δY/δI = 0·18 t ha−1 cm−1, (ii) k = 0·26 t ha−1 cm−1.

(d) Extra K seemed to be helpful in sustaining the early benefit throughout the 3 years.

Clover (Crimson)

One year crop, drilled April and cut (once only) July 1963.

(a) Best yield: 3 t ha−1.

(b) Dι, not detectably different from zero (evidence inadequate).

(c) (i) δY/δI = 0·16 t ha−1 cm−1; (ii) k ≃ δY/δI (?).

(d) First cut completely defoliated irrigated crop, there was no recovery, and the experiment was abandoned.

Clover (Dorset Marl)

One year crops undersown in previous barley crops, 1963 for 1964 (three cuts), 1964 for 1965 (three cuts).

(a) Best yields: 1964, 9 t ha−1 (ɛ ≃ 60 × 10−4); 1965, 8 t ha−1 (ɛ ≃ 60 × 10−4).

(b) Dι ≃ 2·5 cm.

(c) (i) δY/δI: 1964, 0·24 t ha−1 cm−1. 1965, no response; (ii) k: 0·22–0·34, depending on method of derivation.

(d) The response to irrigation was slightly greater on plots not previously irrigated in the barley year. In (c) the uncertainties arise out of excessive rain after the first irrigation in 1965; there was estimated drainage from the irrigated plots but not from the control plots. In 1964, the control plots failed to exploit all the summer rain.

General

There seems to be a need to know two limiting deficits, one, the Dt of these papers, that is a measure of what can be tolerated without any check to growth, and a second that is a kind of maintenance deficit, necessary to keep the crop non-senescent so that it can use all the rain it gets.

Irrigation greatly helped the establishment of all three leys, and both grass and clover responded well to later irrigation. Lucerne did not. In English units, the limiting deficits, Dt, for well-fertilized established crops were, approximately, 4 in for lucerne, 2 in for grass, and 1 in for clover.

1. An experiment was carried out to determine the effect of L-thyroxine implantation upon the wool production and live-weight change of Corriedale and Suffolk × Border Leicester-Merino sheep.

2. Groups fed hay in restricted amounts gave approximately 12% more wool when treated with thyroxine. Since there was no change in fibre diameter, this was presumably due to an increase in staple length.

3. Groups fed hay ad lib. gave no significant increase in wool production when treated with thyroxine, nor did their rate of food consumption alter. Their level of wool production over the 5-month period was approximately the same as that of the thyroxine treated, restricted fed, sheep.

4. All thyroxine-treated groups lost approximately 10% of their live weight. This was in the nature of a steady decrease from the second to the seventh week after treatment. Live weights then remained at about the same level for a further 8–10 weeks when they commenced to return gradually to their original weights.

Two experiments with sugar-beet seed crops at Dunholme Field Station Lincolnshire,1955–7, one at Broom's Barn, Suffolk, 1963–4, and two in Bedfordshire 1965–7, compared transplanting with various direct.drilling techniques. The early experiments were made with multigerm varieties and the 1965–7 experiments with genetic monogerm varieties.

At Dunholme direct drilling under a barley cover crop controlled virus yellows and yielded more multigerm seed suitable for processing than did transplanting. In later experiments transplanting gave variable yields; pests damaged plots transplanted in autumn and those transplanted in spring were susceptible to drought. Many transplants lodged and ripened late and direct drillings produced seed that germinated better.

Direct drilling during July with no cover crop consistently yielded better than undersowing or open drilling in August. To establish a regular, dense stand of plants, which is essential for large yields of seed of good germination was more difficult with than without cover crops. The time the cover crop was removed did not consistently affect yield. Crops sown in summer without cover yield most seed but are most susceptible to disease and are unsuitable for areas with a disease risk.

The effects of manipulation of sward maturity on ingestive behaviour and diet selection of grazing cattle were tested in two experiments using legumes which are equally preferred by cattle. Yearling heifers, in groups of three, grazed plots formed by alternate 2·4 m wide strips of a mixture of birdsfoot trefoil (Lotus corniculatus L.) and white clover (Trifolium repens L.) (BW) and strips of red clover (Trifolium pratense L.) (RC). The treatments comprised four combinations of each of the two swards at two contrasting levels of maturity/height replicated over four successive 3-day periods, in an order which balanced the effect of previous treatments. Observations of the distribution of grazing activity and biting rate were made over 3-hour periods each evening and in the morning of Day 2.

Rate of biting was generally greater on immature than mature swards, and on BW than on RC, with little evidence of interactions between these effects. The animals demonstrated partial preference throughout the two studies, the proportion of grazing time devoted to BW being 0·40±0·010 in Expt 1 and 0·47±0·017 in Expt 2. The distribution of grazing time between sward type and maturity combinations was influenced progressively by herbage mass and height contrasts as strips were grazed down. An overall analysis using the results from these studies and a companion experiment indicated differences between studies in partial preference for BW and RC which appeared to be related to variations in sward morphology.

There is still much difference of opinion as to the effect of temperature on milk production from the point of view of its effect on both quantity and quality at successive milkings or on successive days.

Statistical analyses were carried out on the data obtained under very strict conditions in metabolism stalls with 41 different rations fed to 127 adult non-pregnant dry cows, and with 14 other different rations fed to 35 adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg.

The authors have calculated and studied the correlations between faecal and urinary losses of chloride, chloride excretion with the milk, digestible chloride and chloride balance and many other nutritive factors which were analysed for each of the 55 above mentioned experimental diets.

The results show that the digestion and utilization of chloride is not influenced by the amount of ingested chloride at the time of the trial. The digestion is generally very high, negatively correlated with dry matter, energy, and pentosans intakes, and positively with nitrogen and potassium intakes. But the most important factor in the fate of dietary chloride seems to be the necessity for the cow to eliminate most of the time high amounts of potassium in the urines.

The importance of mechanistic models for ration balancing with forages is indicated and physical limitations to intake emphasized, because these limit energy and nutrient supply to cows grazing forages, especially grass. Ration-balancing models using fresh or ensiled forages to complement pasture will need to accommodate intake limitations due to rumen fill, clearance, chewing or other criteria. The potential of the Cornell Net Carbohydrate and Protein System (CNCPS) model to predict milk production from diets based on pasture and forage supplements was tested using data from two experiments. Data were obtained from studies in which pasture was complemented with contrasting silages including maize, pasture, sulla, lotus and forage mixtures, comprising 0·30–0·40 of dry matter intake (DMI). Twelve diets were used in the evaluation. DMI, liveweight (LW), days in milk, and diet composition were determined during the trials and used as inputs in the model. Across all diets, a significant relationship existed between predicted and actual values for DMI (R2=0·58), milk yield (R2=0·59) and LW change (R2=0·51), but there were still large unexplained sources of variation. No significant mean bias was observed for any of the variables, but the slope of residual differences against predicted values was significantly different from zero for milk yield, LW change and for DMI (P<0·06). The results indicate a satisfactory prediction of milk production when cows are neither gaining nor losing weight, but that a systematic bias exists probably because of the failure of the CNCPS model to account for energy and nutrient partitioning.