Experiments at Sutton Bonington in 1973 and 1974 compared the growth and yield of sugar beet which was handweeded at different stages with that where weed control was entirely by pre- and post-emergence herbicides, used alone and in various combinations. Data from the series of handweeding treatments enabled the crop's minimum weed control requirements to be specified. They indicated that an ideal herbicide would kill all the weeds present when applied at the six-leaf stage, persist in the soil to prevent weed infestation for 4 weeks, but not check the crop to the extent that recovery was incomplete. That the crop was capable of recovering from a degree of early check was clearly evident from the handweeded treatments; it proved possible for crops whose weights had been depressed by 25–30 % when first weeded to recover completely by harvest.

The performance of all post-emergence treatments fell short of these requirements. When the crop was at the six-leaf stage, the earliest emerging weeds were too far advanced to be killed by the herbicide. By themselves, pre-emergence herbicides gave weed control equivalent to only 2 or 3 weeks of handweeding but they did pave the way for more effective use of post-emergence treatments by restricting the spectrum of weed sizes present and sensitizing those plants which did establish. The most effective herbicide regime used in the experiments was the sequence of chloridazon applied pre-emergence followed by two post-emergence applications of phenmedipham. However, phenmedipham clearly checked the crop. Two weeks after application crop dry weight was usually depressed by one-third. Provided weed control was adequate, recovery was usually complete by the end of the season.

1. Radioactive phosphorus was injected into young sheep that had been fed diets low in either phosphorus, phosphorus and vitamin D or calcium. Forty-eight hours after the injection the animals were killed and samples of bone and teeth were removed for specific activity determinations.

2. The specific activities of bone varied according to the site from which it was taken, but in general a strong inverse relationship was found between specific activity and the quality of the skeleton.

3. In teeth that were formed during the period the diets deficient in phosphorus or phosphorus and vitamin D were fed, the specific activities of the dentine and enamel were greater than for corresponding tissues from the control animals.

Knowledge of Ascophyllum nodosum extracts (ANEs) is still limited to avocado ‘Hass’ in the tropics. The objective of this study was to evaluate the effects of two ANEs application methods (foliar v. drench) at four different doses (0, 2.5, 5 and 7.5 ml/l) on the physiological response of three different avocado stages (seedlings and young and adult trees). Foliar or drench ANEs applications were performed monthly for all plants for 16 weeks. The evaluated variables were recorded at 4 and 20 weeks after the start of treatment (WAT). The results showed that ANEs can be applied to the drench or foliar method at doses ≥5 ml/l in the different growth stages evaluated. In seedlings, foliar or drench ANEs applications increased total dry weight (34.5 and 57.9 g for 0 and ≥5 ml/l, respectively) and stomatal conductance (gs) (380 and 205 mmol/m2s for 0 and ≥5 ml/l, respectively) at 20 WAT. In young trees, both application methods also improved growing index (88.6 and 102 cm for 0 and ≥5 ml/l, respectively) and gs (516 and 636 mmol/m2s for 0 and ≥5 ml/l, respectively) at the last sampling point. Adult trees showed that foliar or drench applications at higher doses also caused an increase in fruit yield (3.4 and 8.7 kg/tree for 0 and ≥5 ml/l, respectively) at 20 WAT. In conclusion, the use of foliar and soil ANEs applications at higher doses (≥5 ml/l) can be considered for integrated crop management of ‘Hass’ avocado.

Late planting due to erratic onset of the rainy season is becoming more frequent in the Sahelo-Sudanian climate where cotton is grown, causing seed cotton yield (SCY) loss and higher risk of drought at the end of the crop cycle. Therefore, cultivars should be adapted to late (from July 10) planting date (PD) in Senegal. The aim of this study was to analyse the interaction between genotypes and PD on SCY in Senegal under rainfed conditions. Field experiments were conducted in 2018 and 2019 using a split-plot design (two PDs, eight cultivars) at three experimental stations. Robust analysis of SCY was used to moderate the effect of potential outliers. The average SCY was 1404 kg/ha under early planting, and 714 kg/ha under late planting. The best SCY was obtained under early planting conditions, in environments with good rainfall. The loss due to late planting was significantly affected by cultivar choice. None of the cultivars performed best under both early and late PD. Under early PD, cultivar CS 50 gave the best SCY, while under late PD it was cultivar IRMA Q302. The best performing cultivar on average depended on the proportion of early plantings. A model was developed to identify the best overall cultivar based on the expected proportion of early planting, as a decision support tool for the cotton development company, if only one cultivar is released. The benefit of releasing a second cultivar for late-planted fields is considered.

Biofertilizers, such as arbuscular mycorrhiza fungi and phosphate-solubilizing bacteria (PSB), have been reported to enhance plant growth under water stress conditions. This study aimed to investigate the effect of different biofertilizers on potato photosynthesis and growth under water deficit stress. The experiment was conducted over two crop years (2019 and 2020) using a randomized complete block design with three replications. Four irrigation intervals (70, 90, 110 and 130 mm of cumulative evaporation) and six biofertilizer treatments (PSB, Funneliformis mosseae [FM], Rhizoglomus fasciculatum [RF], PSB + FM, PSB + RF and no use) were applied. Severe moisture stress (130 mm evaporation) compared to no stress (70 mm evaporation) increased substomatal carbon dioxide concentration. The application of biofertilizers improved tuber yield under severe moisture stress, with FM showing the highest increase (62.9%), followed by RF (59.8%) and PSB (48.4%). The use of PSB along with mycorrhizae led to a significant decrease in mycorrhizal colonization percentage at all irrigation levels. The highest percentage of colonization and net photosynthesis was obtained from the application of both mycorrhizal species under irrigation conditions after 70 mm of evaporation. The application of PSB alone resulted in a 14.6% increase in the transpiration rate, additionally, the use of mycorrhiza led to an 18.7% increase in stomatal conductivity compared to no-biofertilizer. The results suggest that the simultaneous use of PSB and mycorrhizae can be effective in mild moisture stress, but in severe moisture stress, the use of mycorrhizal species alone is more effective.

The experimental determination of the digestibility of feeding stuffs has been carried out only to a very limited extent in this country. Nearly all the tables of digestibility-coefficients are of Continental origin, those of Kellner having pre-eminence and being generally adopted. The desirability of carrying out digestibility trials with home-grown feeding stuffs and with new feeding materials obtained from the Colonies and India is, however, apparent, and this is also the case with many of the proprietary feeds which are much used in this country.

Grain yield, plant height, spike length, grain weight per spike, 100-kernel weight, protein quantity and quality of Mexipak wheat grown with four rates of applied nitrogen (0, 75, 150 and 225 kg N/ha) and five rates of applied zinc (0, 1·25, 2·5, 5·0 and 7·5 kg Zn/ha) were measured. All these attributes were affected significantly by nitrogen fertilization in a linear manner. Differences among rates of applied zinc were significant for grain weight per spike, 100-kernel weight, grain yield and protein quantity and quality.

Propionate and glucose metabolism were compared in two groups of Scottish Blackface ewes, one in which ewes had been fitted with vaginal pessaries impregnated with progesterone-analogue for the synchronization of oestrus and the other when ewes were in anoestrus. In ewes given the same amount of feed, the production rate of propionate increased significantly (P < 0·05) from 33 in anoestrous ewes to 44 gC/day in ewes with pessaries. The proportion of glucose-carbon apparently synthesized from propionate also increased significantly (P < 0·05) from 0·31 in anoestrous ewes to 0·44 in ewes with pessaries. The proportion of glucose-carbon apparently recycled was also significantly (P < 0·01) increased from 0·12 to 0·22. No changes were observed in glucose concentration, production rate or oxidation rate between the two groups of ewes.

When growing Cheviot hoggs were wholly maintained indoors on a very poor quality hay fed ad libitum they had a low food intake and consequently were losing weight. A 40 g. supplement of ‘Fodder Yeast’ greatly increased the hay intake of the sheep, and this was accompanied by a steady gain in body weight. Increase in body weight appeared to be accountable for by the increase in food consumption. These findings, obtained in a pilot experiment, require confirmation with a larger flock of sheep.

The genetic parameters controlling the expression of seed yield and the yield components have been studied using both generation mean and triple test cross (TTC) analyses in two crosses of field pea. From generation mean analysis, it is obvious that in addition to significant estimates of additive and dominance components, epistatic components of mean [(i) and (I) types] were also important and duplicate type of epistasis was predominant for all the traits in both sets of crosses. In the TTC analysis, the major genetic component of variance was the additive component, though the dominance component was also found to be significant. There was evidence of epistasis for most of the characters studied. In fact, the overall epistasis (i type) was the major component of epistasis, but the parameter F was found in the non-significant range. The mean performance of the characters studied was higher in randomly-mated biparental progenies (BIPs) but there were more desirable transgressive segregants in the TTC population. Thus the genetic information obtained from both analyses seems to be complementary rather than alternative modes of inheritance in governing the expression of these useful economic traits.

Acetyl-CoA hydrolase which is stimulated by adenosine-5′-triphosphate is present in the cytoplasm of ovine liver and, unlike in certain others species, is not inactivated by cold. It is suggested that this enzyme is involved in a substrate cycle between acetate and acetyl-CoA. The heat produced as a result of such cycling may be as much as 2·5% of basal heat production and may be partly responsible for the increased heat increment that often follows the ingestion of diets that provide large quantities of acetate.

In the breeding of animals like cattle which reproduce slowly relative to the working life of a breeder, time is a factor of major importance. A study has therefore been made of the duration of samples of pedigree herds in order to obtain some indication of the time actually spent by breeders in the selective breeding of dairy cattle.

The samples consisted of pedigree Ayrshire, Jersey and Shorthorn herds, (a) established at various fixed times in the past; and (b) existing in 1939. The former were traced forwards, and the latter backwards, by means of herdbook registrations. Each sample contained not less than 300 herds, and the distribution of durations in each was considered in relation to the movement of population numbers in the whole breeds from which they were drawn.

Four equally spaced feeding levels, estimated to cover the range of commercial practice, were examined using a total of 208 pigs over the live-weight range 28–100 kg. The pigs were penned in groups of six or eight and were balanced for sex within pens. Three centres participated in the experiment contributing five, two and one replicates respectively.

Efficiency of feed conversion was not significantly affected over the range of feed intakes studied, thus daily gain was linearly related to feed intake. A 10 decrease in feed intake increased killing-out percentage by 0·3 unit and decreased backfat thickness by 1 mm at both the shoulder and mid rump. The corresponding changes in the percentages of subcutaneous fat plus skin and meat were similar in magnitude at approximately 0·85 unit.

Muscle quality was reduced with higher feed intakes but weight of liver, as increased. Details of other offal weights and carcass measurements are given.

Short-duration pigeonpea can give up to three harvests in environments with mild winters (e.g. minimum temperature above 10 °C) such as those prevailing in peninsular India (Sharma, Saxena & Green. 1978; Chauhan, Venkataratnam & Sheldrake, 1984). This is mainly due to the short time (about 120 days) taken to produce the first flush, and the strong perennial character of pigeonpea. The seed yield of short-duration pigeonpea in this multiple-harvest system may reach 5·2 t/ha (Chauhan et al. 1984).

An experiment was conducted to examine the effect of fertilizer (triple superphosphate) and stocking rate on animal and pasture productivity on Sumba Island, Eastern Indonesia. The Ongole heifers used in the 1-year experiment gained weight during the wet season and lost weight during the dry season at stocking rates of 0·5 and 1·0 head/ha when grazing native Themeda pasture. The dryseason weight loss was arrested when a prepared seed-bed pasture, which contained 21 % Siratro at the start of the experiment was grazed at a stocking rate of 1·5 head/ha. Increasing the stocking rate to 2·5 head/ha on this pasture resulted in an increase, in the weed component of the pasture from 12 to 84% in 1 year.

The mineral content of plucked samples of pasture indicated that levels of Ca and Mg were generally adequate for growing beef cattle and that Na supplementation would be beneficial. Plant N concentration was below 1·5% in the Themeda and Imperatacomponent but above this in the legume at the prepared seed-bed site. The P concentration in the Themeda and Imperata was always below the 0·24 % level required by cattle, as it was in the legume at the end of the experiment.

The introduction of herbaceous legumes into pastures under set stocking conditions can lead to pasture instability.

Two-year-old tea bushes were given NPK fertilizer on 12 November 1986 and 14CO2 on 22–23 December 1986 and 9–10 January 1987. Late-autumn fertilizer dressing stimulated photosynthate accumulation in the whole bush, especially in overwintering leaves and roots. Large amounts of photosynthates in overwintering leaves provide the nutrition required for early spring budding. Lateautumn dressing also accelerated the transport of photosynthates from leaves to roots in winter, where photosynthates, with absorbed nitrogen, synthesized more animo acids, especially theanine and phenylalanine. The re-use of photosynthates stored in the roots of the dressed bushes during shoot growth the following spring was also facilitated by late-autumn dressing. The contents of amino acids and caffeine in the shoots of dressed bushes were much higher than those in the control, whereas the content of polyphenol was lower than in the control. The results indicate that late-autumn dressing improves the quality of spring green tea.

The analysis of plant competition experiments in which all possible pairs of p genotypes are grown in replacement series is discussed. Two methods of analyses, using models of de Wit (1960) and Gleeson & McGilchrist (1980), are compared. The two approaches, which are shown to be linked algebraically, complement each other in terms of agronomic interpretation.

Sheep are commonly used to graze dairy pastures in the late autumn and early winter, to make use of grass that cows have rejected and to utilize any late growth with a minimum of poaching damage. From late December onwards sheep are less welcome to farmers because of the possible harmful effect on the regrowth of grass in the spring. But if the alternative to grazing from January to March is to bring the sheep indoors and feed them hay or silage, then this cost may be greater than that of the grass lost in the spring. Wilman & Griffiths (1978) concluded that the reduction of yield in spring was directly related to date of last grazing but emphasized that they had made no measurement of herbage remaining at this time. Furthermore, their measurements of subsequent yield were in dry matter to a cutting height of 4 cm with no estimate of the amount of ash or green and dead material.