Experiments testing the effects of variety, sowing date, seed rate, amount and time of application of nitrogenous fertilizer in the spring, application of nitrogenous fertilizerin the autumn and disease control at four sites in the north of England in 1980, 1981 and 1982 are described and the results are discussed.

The siting of the experiments and the seasons had important effects on grain yield and influenced the response to the total amount of nitrogen used and to disease control. The other husbandry factors produced more consistent effects. The choice of variety and drilling date had thegreatest influence on yield. The responses to the different seed rates, to the method of applying nitrogenous fertilizer and to autumn-applied nitrogen were smaller. The effects were additive.

It is argued that differences in the efficiency of light interception by the foliage affects grain yield; that light interception may be influenced by the state of the foliage at the start of the period of rapid growth from April onwards; and that site, season and husbandry all affect the development of the crop up to that point.

A co-ordinated trial has been carried out at twenty-one centres to obtain information on the following problems: does the addition of synthetic lysine to a ‘standard’ ration, widely recommended and used in this country, beneficially influence the performance of growing pigs, and is the effect influenced by whether the source of supplementary protein is white fish meal or soya bean meal ?

In comparison with a ration providing levels of crude protein and lysine recommended in the A.R.C. ‘Nutrient Requirements of Pigs’, the ‘standard’ ration which contained less crude protein and total lysine, produced slightly lower performance, but about the same profit. The performance on the ‘standard’ ration could be improved by the addition of synthetic lysine, but such supplementation would not be profitable unless the cost of synthetic lysine was less than 21s./kg.

The response to added synthetic lysine was similar on rations in which the source of supplementary protein was either white fish meal or soya bean meal.

One of the probable adverse effects of climate change on agriculture is yield loss due to water scarcity. Assessment of meteorological drought risk with the index of crop water deficit (CWD) can help in determining appropriate adaptation strategies to counter such losses. Using daily weather data from 68 stations in Northeast China (NEC) for 1961–2010, the spatial and temporal behaviour of CWD was assessed and the sensitivity of climatic variables related to CWD during the potential growth period of maize was explored. The results indicated that the potential maize growth period decreased by 26 days due to climate warming. The deficit (i.e. a negative value for water demand) decreased from east to west and decreased gradually during 1978–1984 and sharply during 2000–2010. It is noteworthy that NEC experienced severe droughts especially in the 1970s and the 2000s, and relative humidity was the most sensitive parameter affecting evapotranspiration. Regions in the middle of Heilongjiang and Jilin should take precautions concerning climate change effects on CWD, while the northern part of NEC should take precautions concerning changes in temperature and sunshine hours. Growing late-maturing and drought-tolerant maize varieties is therefore a good option for higher production in NEC, coupled with enhancing the availability of water in this limited-rainfall region, and should form a part of the strategy to cope with climate change.

Fat colour is of importance in beef produced for English markets because of discrimination against deep yellow fat. The factors at present known to affect colour are genetic(1,4) and those relating to food supply(2,3), but not much is yet known of the various circumstances or natural conditions under which the colour will vary in shade. It was the purpose of this investigation to determine some of these. Rabbits were selected for the preliminary experiments, as, although it is questionable whether the colouring matter in the fat is quite the same as in cattle (3, 5), it is very probably affected by the same conditions. Experiments could be done quicker and cheaper in rabbits than in cattle on which the results could be tested after the pioneer work in the rabbit was completed.

Resistance in Rossol and Nematex is separately conditioned by single genes. The genes are incompletely dominant and non-allelic. It was not possible to distinguish between homozygous and heterozygous resistant plants in segregating families.

1. An examination was made of four chemical components of herbage—nitrogen, crude fibre, acid-soluble ash and acid-insoluble fraction—from different genetic populations of Lolium perenne, grown in two trials at various related densities, some plots being irrigated. Dates of the frequent harvests were determined by the growth stage of the herbage.

Field experiments were carried out to study the effect of a highly purified paraffinic oil on the efficiency of some insecticidal sprays used for the control of thrips and cotton leafworm. The results show that the oil used separately at the rate of 7·51/ha significantly reduced the population of thrips, but oil-insecticide combinations were superior to oil or insecticides applied alone. The mineral oil increased the efficiency of candidate insecticides against both thrips and cotton leafworm two-fold or more.

In a previous paper on the “Interpretation of Milk Records” the following points were dealt with:

I. Selection of a figure definitive of a cow's milking capability.

II. The influences affecting such a figure.

(a) The usual methods of describing a cow by her total yield per calendar year, per lactation, or per average week are inconvenient both for practical breeding on a large scale and for definite enquiry on the inheritance of milk yield or its possible correlation with other characters. The figures are inconvenient because a variety of circumstances which affect them must be stated for every individual case before such figures can be reliable. Chief of these circumstances are age of cow, length of lactation, number of weeks dry before calving, interval between calving and subsequent service, and time of year of calving.

1. A review of land restoration problems in relation to the soil depth required for successful crops showed that factual information on this orthodox method of restoration was inadequate.

2. A field trial sited on pulverized fuel ash is described in which the relationship between crop yield and soil depth at a range of fertilizer levels was determined; kale, oats, rape, barley and potatoes were the test crops.

3. The crops were divided into two groups, sensitive (kale and barley) and tolerant (oats, rape, potatoes) to ash toxicity, on the basis of their response to soil depth at the high fertilizer level. Quadratic expressions relating yield to soil depth, over the range 3–36 in. at each fertilizer level were fitted to the data for each crop group.

4. Yield isoquants, derived from the fertilizer response curves at each soil depth, enabled soil depth-fertilizer level combinations to be ascertained for producing a given level of crop yield. Fertilizer could be substituted for soil more effectively for tolerant than sensitive crops.

5. A 12 in. cover of soil together with 1½ times the normal farm fertilizer dressing for the crop was the minimum for acceptable yields. Fertilizer use may have to be increased to twice normal dressings to maintain yields if soil depths are reduced to below 12 in.

6. Crop yields were not increased by a soil covering greater than 24 in. deep.

The effect of exchangeable sodium percentages (ESP) of 86, 61, 43, 33 and 28 on forage yield and chemical composition of four cultivars of pearl-millet (LC-2, LC-5, LC-6 and LC-7) was studied under field conditions during 1981 and 1982. Dry and green forage yields were significantly higher at 28 ESP over other ESP values. Increasing ESP decreased the yield and concentration of Ca, K and P but increased that of Na in the plants. Cultivar LC-5 was found to give the best performance under sodic soil followed by LC-7, LC-6 and LC-2. At an early stage of crop growth (45 days), cv. LC-2 had significantly lower concentrations of Ca, K and P and a higher Na concentration compared with other cultivars.

1. For experimental purposes the treatment of cotton seed with sulphuric acid, prior to planting, has always been the custom at Barberton. In view of the doubts about the benefits of this treatment which were expressed by Christidis (1936), experiments were carried out at Barberton in the 1938–9 and 1939–40 seasons, to provide concrete proof, if possible, of the advantages which it was believed resulted from it.

2. A series of stand counts made soon after germination revealed definite benefits with acid treatment, in all experiments in both seasons. The seedlings emerged considerably earlier than those from untreated seeds, and the stands recorded at the final counts revealed a significant advantage for acid-treated seed, throughout the experiments. The second season's experiments gave a greater advantage for acid treating when meteorological conditions were bad than when they were good, but the advantage even with ideal weather was still significant. The benefit of acid treatment was shown to be greater, too, with poor samples of seed than with good, and with the smaller seed rate than with the greater.

1. Fractionation studies are reported which show that in young spring pasture of low magnesium content, more than 50% of the magnesium is watersoluble, the proportion being higher in pasture at the seeding stage than in young leafy material.

2. Insoluble magnesium constituted about onethird of the magnesium in young leafy pasture and about one-fifth to one-quarter in pasture at the seeding stage.

3. Acetone-soluble magnesium varied from about 12% of the total in young leafy grass to 5% or less in grass at seeding.

4. Fertilizer treatments, though affecting the total magnesium contents, apparently did not affect the proportions in the different fractions.

A low sodium diet was given to Scottish Blackface ewes over two reproductive seasons. It provided a total of 3–7 mmol sodium per day, except during lactation when the intake was about 11 mmol sodium per day. Control ewes were given the same diet supplemented with sodium chloride to Agricultural Research Council recommended concentration which was about ten times greater than that in the experimental diet.

The ewes remained clinically healthy throughout the experiment. The length of gestation and the birth weight of lambs were unaffected by diet. The number of lambs born alive per ewe lambing was unaffected by year or diet.

The percentage of ewes producing twins was similar in control ewes in both years at about 64; in treatment ewes this was 70% in year 1, and 50% in year 2. Lamb mortality was higher in both years in the treatment ewes than in control ewes. None of these differences reached significance.

Neural networks (NNs), especially the group method of data handling-type NN (GMDH-type NN), are new tools in modelling growth and production in poultry systems. In the present study, the GMDH-type NN was used to model early egg production (EEP, eggs/bird) in Ross 308 broiler breeders (BBs) from 24 to 29 weeks of age based on their dietary energy and nutrient intake. The selected input variables were intake levels of metabolizable energy (ME; MJ/bird/day), crude protein (CP; g/bird/day), methionine (Met; g/bird/day), and lysine (Lys; g/bird/day). A sensitivity analysis (SA) technique was utilized to evaluate the relative importance of input variables on model output. The GMDH-type NN revealed a high ability in the modelling of EEP based on the input variables investigated. The SA results indicated that the models developed showed most sensitivity to dietary intake of Met, followed by dietary intake of Lys, ME and CP, respectively. The maximum sensitivity of each input variable was considered as the optimum value for maximizing EEP in BB. The suggested optimum values for dietary nutrient intake were as follows: 1·9–2·1 MJ/bird/day for ME, 23 g/bird/day for CP, 0·65–0·8 g/bird/day for Met and 1·4–1·5 g/bird/day for Lys.

The effect of different concentrations of aminoethoxyvinylglycine (AVG; 0 (control), 250, 500, 750 and 1000 mg/l), an ethylene biosynthesis inhibitor, on grape berry set and fruit quality was evaluated under vineyard conditions. Treatments were performed on ‘Alphonse Lavallée’ grape cultivar at full bloom stage for two years. Cluster and berry growth (length, width and weight), firmness, soluble solids content, yield, berry set, anthocyanin content and colour parameters were determined on treated and untreated (control) fruits. As a result of the study, the effects of AVG concentrations on firmness were not significant. When AVG applications were compared with control, it is determined that some quality properties were statistically affected, the others were not. Fruit set was increased by lower concentrations of AVG (250 mg/l) and anthocyanin content was increased by higher concentrations of AVG (750 mg/l).

Two experiments were conducted to evaluate the effect of short transport stress on ewes during di-oestrus and pro-oestrus. In Experiment 1, intra-vaginal sponges containing fluorogestone acetate were inserted into ewes for a period of 12 days. A gonadotrophin (PMSG) injection was given at the time of sponge withdrawal to induce oestrous. To dissociate the possible effect of PMSG during pro-oestrus, a second experiment was designed in which prostaglandin was used as the oestrous induction factor. Ewes in both experiments were subjected to 30 min of transport by truck. In addition, oestrous behaviour and serum cortisol concentration were evaluated. Control groups consisted of un-transported ewes. In both experiments, cortisol concentration was greater (P <0·01) in transported than in un-transported animals. No difference (P> 0·05) was found between moving the ewes during pro-oestrous or di-oestrus (0·30±0·03 v. 0·53±0·18 ng/ml and 3·88±0·97 v. 2·94±0·73 ng/ml in Experiment 1 and 2 respectively). The number of ewes detected in oestrous was similar (P>0·05) among those stressed during di-oestrus, pro-oestrus or un-transported animals within each experiment (66, 47 and 42% respectively in Experiment 1 and 96·7 in all situations in Experiment 2). In general, higher cortisol concentration and more ewes displaying oestrous behaviour were detected in Experiment 2. It was concluded that under the conditions of these experiments, no difference was found in the proportion of ewes displaying oestrus regardless of the phase of the oestrous cycle in which they were transported.

Under the short-day conditions and cool temperatures prevailing from January to March in the Nile delta, Egypt, potato (Solatium tuberosum) seedlings grown from true potato seed formed tubers in the nursery when the plants were less than 5 cm in height. In order to examine the hypothesis that slow field establishment after transplanting and low tuber yields of these seedlings were caused by premature tuberization, different treatments to delay tuberization were applied in the nursery before transplanting.

Increasing the air and soil temperature in the nursery accelerated both the development of the above-ground and below-ground shoot organs, but did not improve field establishment of the seedlings after transplanting. Extension of the photoperiod with incandescent dim light, exogenous application of gibberellic acid (GA), and removal of the shoot apex to encourage the growth of lateral branches from the leaf buds increased biomass allocation to the above-ground shoot organs, decreased tuberization in the nursery and accelerated field establishment of transplanted seedlings. Extension of the photoperiod was the most effective treatment to delay tuberization, and doubled the final tuber yield from transplanted seedlings.

The results are in agreement with the hypothesis that poor field establishment and low final tuber yields from potato transplants may be caused by the presence of strong tuber sinks at transplanting, which reduce assimilate partitioning towards the roots and above-ground shoots.

Plants of three populations of Festuca arundinacea, syn. 1 and syn. 2 (North African) and S. 170 (British) were subjected to 3 h cold stress treatments in the range 13–25 °F. Such treatments were applied independently to either roots or shoots, the untreated plant portions remaining at 35–40 F°.

In all populations considerable tiller death occurred following exposure of roots to temperatures of 17 °F or below; however at no temperature was there complete killing of tillers. Tiller deaths occurred following shoot exposure to temperatures below 21 °F in syn. 1 and syn. 2, and below 19 °F in S. 170. Universal mortality occurred in all populations after shoot exposure to 13 °F.

The degree of insulation of the root: shoot junctions affected survival of both roots and shoots in all populations. Discrepancies between apparent damage to plant parts following treatment, and subsequent survival, suggested that the ability of plants to replace damaged parts might influence survival.

Conclusions are included from the completed programme of growth cabinet studies on cold tolerance of F. arundinacea populations reported in the present series of papers.

In factorial experiments covering a range of sowing dates and insecticide treatments the numbers of fleabeetle, jassid and whitefly on cotton in the Sudan Gezira were shown to be strongly influenced by the date of sowing and the age of the crop.

Attack by fleabeetle was most severe on cotton seedlings from July and early August sowings. Few fleabeetle were found on either more mature plants from these sowing dates or on seedlings from later sown cotton.

Whitefly numbers were highest on late July and early August sown cotton. Peak numbers were attained attained in late September and October and then fell to very low levels in November irrespective of date of sowing.

Jassid numbers were related both to plant age and to time of year, more being found on cotton sown, in July and early August early in the season and on later sown cotton later in the season. The highest numbers were found in November and December at which time populations were higher on cotton sown in mid-August or later than on earlier sown cotton.

A recent paper by W. B. Haines on soil shrinkage is discussed and his explanation of residual shrinkage criticised in the light of earlier work by the writer on evaporation of water from soil. A modification of Haines' tentative explanation is suggested.

The experimental results of Haines nave rendered it possible to define more clearly than previous work allowed the significance of the critical moisture content and the divergence between the first sloping portions of the rate of evaporation curves and the corresponding portions of the vapour pressure curves.