Four growth regulators were tested: N-dimethylaminosuccinamic acid (aminozide); N-pyrrolidinosuccinamic acid (F529); 2-chloroethyldimethyldodecylammonium chloride (JF2579); potassium 2(3-chlorophenylcarbamoyloxy) propionate (JF3072); all shortened stems. JF2579 and JF3072 were phytotoxic and lessened yield. Aminozide and F529 (tested in 1970 only) did not affect yield in 1970 but aminozide increased yield by 28% in 1971. Seed rates and row spacings had small effects on yield which varied with season. Growth regulators did not interact with seed rates or row spacing. Plant density and growth regulators had effects on yield via the number of stems and pods per stem. The effects of season on yield were greater and were caused via 100 grain weight. Speculative hypotheses are suggested to explain the different actions of season and treatments.

The evidence from these combined variety × plant density experiments, together with the additional data on varieties previously reported (Bunting & Willey, 1958), suggests that, for fodder or ensilage production in Britain, the varieties we have designated as ‘medium’ (i.e. within the range represented by the hybrids Wis. 275 and Wis. 341 A), sown to give a final density of 9–12 plants/sq.yd. would be most suitable. Higher plant populations probably give slightly higher yields, but the differences will rarely be of practical importance and are likely to be offset by the greater incidence of lodging and the consequent increase in harvesting difficulties.

The phosphorus status of five Nigerian coastal plain sands was evaluated by determining the relative abundance of the various P forms and the P adsorption capacities of the soils. Total P ranged from 4460 to 1129 mg/kg. Organic P had a range of 23–232 mg/kg and formed below 30% of total P in four of the profiles but above 50% in the hydromorphic Otegbo profile. The relative distribution of the various inorganic forms was in the increasing order of residual P, active P and occluded P, except in the Onne profile in which the residual P was relatively the least abundant. The relative distribution of the active P forms was in the decreasing order of Fe-P, Al-P and Ca-P.

The adsorption capacity varied widely among the soils. The amount adsorbed from the addition of 150 mg/100 g of soil ranged from 40–2 to 86–2 mg/100 g and was related to the clay content. The adsorption at 0–3 mg/1 P in equilibrium solution ranged from 19 to 265 mg/kg. The subsoils generally adsorbed more P than the surface soils. The P requirements of the soils estimated from the sorption capacities were in the low and medium ranges.

There are extensive areas in Scotland and other parts of Britain where, because of low soil cobalt status, the cobalt concentration of pasture herbage is below the 0–1 /fg/g D.M. regarded as the requirement for grazing ruminants (Agricultural Research Council, 1965). A common method of overcoming the effects of cobalt deficiency in livestock occurring within these areas is to apply cobalt sulphate to the pasture. Following work carried out by Stewart, Mitchell & Stewart (1941, 1942) and Stewart etal.(1946) the standard recommended application of cobalt sulphate for pasture has remained at 2 kg/ha for many years, an application generally expected to last for 3–5 years. However, in South East Scotland there are doubts about the adequacy of such treatment which has led to a reappraisal. Significant increases in uptake of cobalt by herbage following applications to land at this rate are not always observed and sometimes there is no appreciable increase in ‘available’ soil cobalt as determined by acetic acid extraction.

Eighteen male cross-bred lambs (aged 2–5 days) in two equal groups were given artificial milk diets of either low- or high-protein content; subgroups of three lambs were slaughtered after 2, 4 and 6 weeks on experiment. The composition of the change in empty body weight (E.B.W.), and the chemical composition of the change in weight of the separate compartments and organs, were determined by the comparative slaughter method.

Lambs given the high-protein diet made significant gains in weight and in all chemical components in all periods. The composition of their E.B.W. was closely related to E.B.W. regardless of age. Lambs given the low-protein diet made only small gains in weight in 6 weeks, of which 76% was fat. The chemical composition of their E.B.W. was closely related to E.B.W. within each age group. The net gain of protein of these lambs in 6 weeks represented only 1% of the total weight gain, and over 50% of the protein gain was in wool. The skin and blood lost protein during the first 2 weeks, and failed to recover this loss during the remaining 4 weeks. Other organs lost protein initially but recovered this loss between 2 and 6 weeks.

It was concluded that the initial loss of protein represented the labile protein reserves of the lamb, and the subsequent recovery was an adaptation to the low-protein diet. Furthermore, the results with both diets indicated that the skin and blood were the most inefficient of the organs in the body in utilizing the available N during a period of protein deficiency, or during a period of abundance in the dietary supply of N.

A comparison of leaf-area index (L) in the postflowering period was made between a single cross maize hybrid in Rhodesia and a winter and a spring wheat variety in England. At the beginning of the period L of the maize was lower than that of the wheat but it remained near its initial value for a relatively long time, whereas L of the wheat decreased rapidly. The proportion of L consisting of sheath was much lower in the maize than in wheat. Grain yield was higher in the maize largely because of its longer period of grain growth. In Rhodesia maize might benefit from a greater L than that recorded in this study. The high yields achieved by maize are partly due to the relatively long life of its leaves.

The response of soil microbial communities to soil quality changes is a sensitive indicator of soil ecosystem health. The current work investigated soil microbial communities under different fertilization treatments in a 31-year experiment using the phospholipid fatty acid (PLFA) profile method. The experiment consisted of five fertilization treatments: without fertilizer input (CK), chemical fertilizer alone (MF), rice (Oryza sativa L.) straw residue and chemical fertilizer (RF), low manure rate and chemical fertilizer (LOM), and high manure rate and chemical fertilizer (HOM). Soil samples were collected from the plough layer and results indicated that the content of PLFAs were increased in all fertilization treatments compared with the control. The iC15:0 fatty acids increased significantly in MF treatment but decreased in RF, LOM and HOM, while aC15:0 fatty acids increased in these three treatments. Principal component (PC) analysis was conducted to determine factors defining soil microbial community structure using the 21 PLFAs detected in all treatments: the first and second PCs explained 89.8% of the total variance. All unsaturated and cyclopropyl PLFAs except C12:0 and C15:0 were highly weighted on the first PC. The first and second PC also explained 87.1% of the total variance among all fertilization treatments. There was no difference in the first and second PC between RF and HOM treatments. The results indicated that long-term combined application of straw residue or organic manure with chemical fertilizer practices improved soil microbial community structure more than the mineral fertilizer treatment in double-cropped paddy fields in Southern China.

The early authorities, Mulder, de Saussure, Berzelius and others, considered the whole of the precipitate obtained by adding acid to an alkaline extract of soil to be humic acid,—a single substance to which they assigned a definite formula. Hoppe-Seyler and others found, however, that the precipitate was not homogeneous; a portion dissolved in alcohol, which he named hymatomelanic acid. It was from this that Schreiner and Shorey isolated a number of organic acids, all of which were either colourless or only faintly coloured.

Selfed and diallel progenies of selected clones of Lolium perenne were subjected to four nitrogen rates—0, 225, 450 and 675 kg/ha of N per annum. The herbage was analysed for total nitrogen (N), digestible dry matter (DMD), digestible organic matter (D) and acid-pepsin solubility was determined on total (PS) and organic matter (POMS) in 1967 and 1968.

Data for the percentage composition and the yield of quality components are presented with the variances of general (g.c.a.) and specific (s.c.a.) combining abilities for these characters. The g.c.a. and s.c.a. interaction with nitrogen is partitioned.

For percentage quality components and yields there were significant effects of years, nitrogen rates, progenies and their interactions. The variance for g.c.a. for all percentage quality components was not significant in 1968 but in 1967 all were significant except for total N. For yields, only the g.c.a.'s for PS and POMS were significant in 1967: no g.c.a.'s were significant in 1968.

There were considerable differences between years for heritability values. For digestibility the predicted performance of a theoretical F2 synthetic was little better than the mean of the population from which it was derived.

The implication of these studies in the formulation of a grass breeding programme is outlined.

Populations derived from a diallel set of crosses involving five inbred Upland varieties were tested for bacterial blight resistance at Wad Medani in the Sudan and at Namulonge in Uganda. Four of the varieties carried a known B gene for resistance; no B gene was present in the fifth, which was used as a susceptible parent. The importance of genotype/environment interaction was emphasized and it was found that the B genes did not maintain the same dominance relationships at the two sites.

The Reba gene, B9L, segregated as a gene or ‘effective factor’ of large effect but Mendelian segregation was not discernible in hybrid populations not involving Reba. Most of the genetic variance was accounted for by additivity and dominance. Although statistical analysis failed to reveal epistasis there was a strong interaction in the B2 × B6 cross.

At Namulonge, where it was possible to test for leaf and boll resistance, the proportion of dominant and recessive alleles was the same for both phases of the disease.

Populations of spaced plants of each of the four American upland cotton varieties Deltapine Smooth Leaf, Rex Smooth Leaf, Pope, and Rex and one African upland variety, Bar 7/8, were grown in the 1965–6 wet season at Kimberley Research Station, in the Ord River valley, Western Australia. The number of bolls, boll weight, lint percentage, seed cotton yield, lint yield, micronaire value, mature height, and morphological type were recorded for each plant.

For all varieties the range of each attribute was wide; for example, for a typicalvariety, boll weight ranged from 3·0 to 7·8 g, lint percentage from 30·5 to 43·5%, micronaire value from 3·3 to 5·9 units, and mature height from 78 to 195 cm.

The most variable varieties judged on coefficients of variation were those maintained at the station for the longest period without selection while the most recent accession was the least variable.

Frequency distributions for all attributes in each population departed significantly from normality: the majority showed both significant skewness and kurtosis. Positive skewness shown for the yield parameters seed-cotton yield, lint yield, boll number and boll weight in all varieties suggested there was scope for improvement by selection. Negative skewness for lint percentage was found in three varieties, suggesting previous intense selection for this trait. The coefficient of variation of lint percentage with one variety (Deltapine Smooth Leaf) was considerably less than that recorded 30 years earlier for its predecessor D x PL 11 A.

Covariance adjustments to seed cotton yield of individual plants, based on various hypotheses of the relationship between a plant's yield and that of its neighbours failed to give reductions of consequence in the variability of yield. It was concluded that inter-plant influences were far more complex than the models assumed.

Four steers, average body weight 260±15 kg, fitted with portal catheters were used in a 4×4 Latin Square design to evaluate the influence of dietary protein degradability in the rumen on peptide and amino acid fluxes across the gastrointestinal tract. Dietary protein degradability was regulated by using different protein sources and the diets were calculated to contain 130 g CP/kg and 9·62 MJ ME per kg DM. Plasma concentrations of amino acids were analysed before and after acid hydrolysis of samples first subjected to chemical deproteinization and physical ultrafiltration, and peptide amino acids (PAA) were calculated as the difference between total and free amino acids (FAA). Portal blood flow and arterial concentrations of FAA and PAA were not affected by protein degradability or by diet. Venoarterial concentration difference and net portal flux of FAA tended to increase (P < 0·10) with increase of degradable protein intake. Portal-arterial concentration difference (P < 0·05) and net portal flux (P < 0·10) of PAA increased linearly as dietary protein degradability increased. The proportion of PAA in total amino acid (FAA+PAA) net flux was not modified by dietary protein degradability or by diet, and the mean value as a proportion was 0·32. The major PAA absorbed were glutamate, leucine, aspartate and lysine for all diets, accounting in total for 0·50 of PAA flux. The results demonstrate that PAA may contribute significantly to AA flux across the portal-drained viscera (PDV) of steers, and both FAA and PAA net fluxes can be affected by degradable protein intake.

1. Sweet corn is adjusted to the conditions of North America. British climatic conditions differ from American in the longer summer day-length and in lower spring soil temperature. Cold hardiness, i.e. the ability of the seed to germinate after lying in cold, wet soil, is therefore an important factor when introducing sweet corn into Britain.

2. Varieties germinate differently according to when they are sown. Furthermore some varieties germinate better than others in March and even April, thus demonstrating the genetic nature of cold hardiness.

3. Selections were first made from plants surviving March sowings and in later years, as hardiness increased, from those surviving February sowings.

4. Selections for hardiness were made in (i) Canada Gold, (ii) Early Golden Market sweet corn, (iii) Golden Standard Maize dent corn and (iv) derivatives of Peruvian crossed sweet corn.

5. All responded rapidly in their increased ability to germinate from February sowings except the Peruvian sweet derivatives which failed to show much improvement.

6. Future breeding work in Britain depends on establishing from our selections cold hardy inbreds able to combine well in giving good F1's for commercial use.

The growth patterns of impetus groups of muscles were mostly not significantly affected by rate of growth of the musculature. One small group – the low/average impetus muscles – had a significantly lower ‘b’ value in the calves fed at a high plane. It appears that under differences of feeding encountered commercially, no changes of practical importance in the relative growth of muscles are likely to be produced which are attributable to rate of growth of the musculature.

A population of 12 ryegrass genotypes was grown at densities of 0·25, 16 and 8 ryegrass + 8 white clover plants per sq ft and was periodically cut to stubble heights of O5 in. or 3 in. For individual plants, yields, tiller numbers, tiller lengths and emerged inflorescence numbers were recorded. Density was the main determinant of plant size, but cutting-height effects were shown, most markedly for the number of inflorescences.

Initially the frequency distribution of plant weight was positively skewed under all treatments, but became less skewed for the population at 0–25 plants per sq ft and more skewed for the population at higher densities. Development of the skew was delayed where white clover was grown. Generally, increasing skew was associated with increasing positive kurtosis.

Frequency distributions of tiller numbers were less skewed than those of yields. Frequency distributions of tiller length were less skewed than the corresponding higher density distributions of yield and tiller number.

Treatment effects on population means demonstrate the different responses which may be obtained with widely spaced plants or those grown in swards. Changes of the frequency distribution of the population are interpreted using the model of Koyama & Kira (1956) and are related to procedures assessing the performance of plants under selection for growth in swards.

Grain-filling, as the final growth stage of rice, is sensitive to environmental temperature change. Previous studies mainly concerned about the effects of high temperature stress during grain-filling on rice growth, and most experiments were carried out with pot for cultivating rice and greenhouse for warming. This research investigated the response of rice grain-filling of superior spikelets (SS) and inferior spikelets (IS) of two japonica cultivars to elevated temperature during grain-filling stage under open-field warming conditions in lower reaches of Yangtze River Basin using free-air temperature enhancement facility. Results indicated that rice yield was not significantly changed by warming less than 4°C. SS and IS showed different responses to elevated temperature during the grain-filling stage, whereas there were similar trends between two cultivars and years. For SS, although elevated temperature enhanced its filling rate during the early grain-filling period, and caused a shorter grain-filling period and a lighter grain weight; for IS, elevated temperature improved its grain weight by enhancing its filling rate during middle and late grain-filling period due to the increased number of days with suitable temperature. For both SS and IS, key starch biosynthesis enzymes and indole-3-acetic acid content exhibited generally a similar dynamics trend with grain-filling rates, and these sink strength parameters presented higher levels under elevated temperature relative to natural temperature for IS during middle and late grain-filling period. Consequently, warming less than 4°C presented different influences on SS and IS; the improvement of IS filling under warming regime was associated with the intensification of grain sink strength.

A series of experiments investigated mineral supplements for the correction of negative calcium and phosphorus balances in horses fed tropical grass hays containing more than 0·5% total oxalate.

A daily supplement of a soluble calcium source was retained with an efficiency of 60% implying no interference with calcium absorption from supplements by oxalate or other factors in the hays.

The palatability of limestone, rock phosphate, dicalcium phosphate, a limestone and dicalcium phosphate mixture and mono-ammonium phosphate was tested with a view to providing a supplement once weekly. With the exception of the latter, all were consumed readily when mixed with 50–60 % molasses (w/w) and hourly intakes of 200 g calcium and 50 g phosphorus were recorded.

In balance trials using horses fed tropical grass hays, 1 kg of either rock phosphate, or a mixture of limestone and dicalcium phosphate (1:2, w/w), each mixed with 1·5 kg molasses, was fed on the 8th day of a 14-day balance trial. The retention of calcium from the supplements ranged from 19 to 41% and that of phosphorus from 22 to 42%. The passage time for unabsorbed minerals was about 4 days. This amount of supplementation can accommodate calcium and phosphorus losses of at least 20 and 10 mg/kg live weight/day respectively. A supplement of 1 kg limestone overcame a negative calcium balance of 20 mg/kg live weight/day but did not overcome a negative phosphorus balance.

The results of recent trials for winter wheat (Triticum aestivum L.) have influenced farming practice in the UK by encouraging the use of lower seed rates. Spink et al. (2000) have demonstrated that, particularly if sown early, wheat can compensate for reduced plant populations by increased tiller production.

Results from seed-rate trials are usually analysed separately for each environment or each combination of environment and variety, and not combined into a single model. They therefore address the question of what the best seed rate would have been for each combination, rather than answer the more relevant question of what rate to choose for a future site. The current paper presents a Bayesian method for combining data from seed-rate trials and choosing optimum seed rates: this method can incorporate information on seed and treatment costs, crop value and covariates. More importantly, for use as an advisory tool, it allows incorporation of expert knowledge of the crop and of the target site.

The method is illustrated using two series of trials: the first, carried out at two sites in 1997–99, investigated the effects of sowing date and variety in addition to seed rate. The second was conducted at seven sites in 2001–03 and included latitude and certain management factors. Recommended seed rates based on these series vary substantially with sowing date and latitude.

Two non-linear dose-response functions are fitted to the data, the widely used exponential-plus-linear function and the inverse-quadratic function (Nelder 1966). The inverse-quadratic function is found to provide a better fit to the data than the exponential-plus-linear and the latter function gives estimated optimum rates which are as much as 40% lower. The economic consequences of using one function rather than the other are not great in these circumstances.

The method is found to be robust to changes in the prior distribution and to other changes in the model used for dependence of yield on sowing date, latitude, variety and management factors.

In alpine regions of the Qinghai-Tibetan Plateau of China, perennial vetch (Vicia unijuga A. Br.) productivity is often low and variable, constrained by the cold and erratic precipitation environment. The aim of the current study was to identify the soil-environmental modifications needed in harsh alpine environmental conditions for improvement of perennial vetch growth, forage biomass production and seed yield. A 3-year field experiment was conducted in an alpine region of China to evaluate the effects of modified soil temperature and moisture conditions generated by three mulching treatments – plastic film mulching (FM), removal of plastic film mulching at the 30% flowering stage and barley straw mulching – on perennial vetch productivity. Higher mean soil temperature and soil water content were recorded in the FM treatment than in the control and other treatments. This enhanced perennial vetch growth, as indicated by higher photosynthetic rate, higher leaf area index and greater above-ground dry matter, and thus higher seed yield and water productivity. Examination by multiple linear regression showed the relative contribution of mean soil temperature to the variations in photosynthetic rate, above-ground dry matter and seed yield were greater than soil water content, whereas the reverse occurred in seeds/pod. In conclusion, the FM treatment provided adequate soil temperature and water resources to improve photosynthetic rate, above-ground dry matter, seed yield and water productivity, and thus increased the productivity potential for perennial vetch in the alpine region. The current research provides scientific support for large-scale perennial vetch cultivation and management in alpine regions.

The objective of the current paper was to apply mixed models to adjust the growth curve of quail lines for meat and laying hens and present the rates of instantaneous, relative and absolute growth. A database was used with birth weight records up to the 148th day of female quail of the lines for meat and posture. The models evaluated were Brody, Von Bertalanffy, Logistic and Gompertz and the types of residues were constant, combined, proportional and exponential. The Gompertz model with the combined residue presented the best fit. Both strains present a high correlation between the parameters asymptotic weight (A) and average growth rate (k). The two strains presented a different growth profile. However, growth rates allow greater discernment of growth profiles. The meat line presented a higher growth rate (6.95 g/day) than the lineage for laying (3.65 g/day). The relative growth rate was higher for lineage for laying (0.15%) in relation to the lineage for meat (0.13%). The inflection point of both lines is on the first third of the growth curve (up to 15 days). All results suggest that changes in management or nutrition could optimize quail production.