Field experiments, conducted on alluvial soil of Jalandhar during 1984–5 and 1985–6 with four rates of application each of N, P and K and four potato cultivars, Badshah, Bahar, Lalima and Jyoti, revealed significant responses to N and K. Badshah, Bahar and Lalima responded to 240 kg N/ha while Jyoti responded to 160 kg N/ha. Badshah did not respond to K. Bahar responded to 150 K/ha whereas both Jyoti and Lalima responded to 50 kg K/ha. Varietal responses to N were related to yield and crop duration while the responses to K were related to K composition of tubers. N showed inconsistent effect on percentage dry matter of tubers, but K decreased it. N increased concentration of N and P but decreased that of K.

In a field experiment conducted from 1981 to 1984 on alluvial soil (Ustochrept) of Jalandhar, green manure (GM) of dhaincha, sannhemp, pearl millet and moong did not affect tuber yield in the 1st year but increased it in the 2nd and 3rd years. GM of dhaincha and sannhemp were more effective than the moong in reducing responses of potatoes to K. GM of pearl millet was as effective as the dhaincha or sannhemp in 1981–2 and 1982–3 when buried 55 days after sowing but was inferior in 1983–4 when buried 85 days after sowing and resulted in reduced concentrations of N and P in potato plants. GM of dhaincha, sannhemp and pearl millet increased concentration of K in potato plants and available K in soil. GM of dhaincha and sannhemp, in particular, increased soil available K by decreasing non-exchangeable K whereas GM of pearl millet increased soil available K without affecting non-exchangeable K.

Azolla and blue-green algae (BGA) biofertilizers in rice cultures were compared with farmyard manure (FYM), Azolla and Eichhornia compost, green manuring with Sesbania and chemical nitrogen fertilizer as urea. Growing Azolla crop in rice field once before transplanting and twice after transplanting produced a fresh biomass of Azolla of 46·7–47·6 and 36·4–40·6 t/ha, containing 83·4–92·2 and 64·7–70·4 kg N/ha, with the rice varieties IR-36 and Mahsuri, respectively. The BGA produced only 7·9–8·9 and 5·2–7·2 t fresh biomass/ha, containing 19·5–20·6 and 14·8–19·3 kg N/ha with IR-36 and Mahsuri, respectively.

In the 1st year of the experiment application of FYM, Eichhornia and Azolla compost and green manuring of Sesbania produced lower grain and straw yields and panicles than 60 kg N/ha as urea, but during the 2nd year all these treatments showed responses equal to that of 60 kg N/ha as urea. Nitrogen concentration and uptake by rice in these treatments were, however, lower than that of 60 kg N/ha as urea. Growing and incorporating Azolla once before and twice after transplanting produced higher grain and straw yields, and more panicles, and also showed higher nitrogen concentration and uptake by rice than those of organic and green manures. The BGA inoculation to rice with 30 kg N/ha as urea produced less grain and straw, and fewer panicles, and also showed lower nitrogen concentration and uptake by rice than 60 kg N/ha as urea and other organic manures. Of the two rice varieties, IR-36 produced more grain and panicles than Mahsuri, but Mahsuri produced more straw.

Total nitrogen, organic carbon and available phosphorus of soil after harvest of the rice increased owing to the application of organic manures, green manures and Azolla and BGA biofertilizers. The green manuring of Sesbania and using Azolla once before and twice after transplanting and FYM showed highest organic carbon and available phosphorus in soil after harvest.

Twenty potato cultivars and breeder's clones were subjected to tests of external damage susceptibility at two sites. At one site tubers were, as in usual agricultural practice, lifted by mechanical harvester, and damage indices were subsequently assigned to each clone. At the other site tubers were harvested by hand on two dates. Drop tests were carried out on this material after 1 week in store and also, in the case of the laterdug (maincrop) material, after 3 months.

Ranks based on damage indices were approximately as expected from previous cultivar assessments carried out by other workers. The mean drop test scores showed varying degrees of rank correlation with the damage indices. The highest correlation was with ranks obtained from the drop test on early-harvested material. It was concluded that this was because damage had been inflicted in both cases before skin curing had occurred.

Development was studied in winter wheat sown after rape or after oats in September 1984, 1985 and 1986, and in October 1985. N03-N residues from rape in October exceeded those from oats by 60, 50 and 40 kg N/ha respectively in the 3 years. Previous crops affected development only in the 1984–5 season. The first 12 apical primordia were initiated faster after rape; thereafter rates were similar, wheat after rape having two more primordia than wheat after oats. Final numbers of leaves and spikelets were each increased by one. The first five leaves appeared faster after rape so that from December onwards the number of emerged leaves was one more after rape than after oats. The double ridge and terminal spikelet stages occurred 8 and 4 days respectively earlier after rape than after oats. Development was unaffected by N fertilizer applied in November or at various times from February onwards, although growth and N uptake were increased. Drought during autumn 1985 delayed emergence of the September-sown wheat and slowed the rates of initiation of the first ten primordia and appearance of the first four leaves. Consequently the number of shoots per plant in December was only about three cf. six in the other 2 years.

Experiments harvested in 1984, 1985 and 1986 tested the effects of combinations of three seed rates (12, 24 and 36 seeds sown/m2), with three sowing dates (late September and approximately 28 and 56 days later) and two sowing methods (conventionally drilled and ploughed-in after broadcasting) on field beans grown on Clay-with-Flints soil at Rothamsted.

Grain yield was always largest with the earliest sowing, smallest with the latest. The seed rate needed to achieve the largest yields increased with lateness of sowing. For September sowings the smallest seed rate was sufficient in 1984 and 1985 but 24 seeds/m2 were needed in 1986 when the exceptionally severe winter killed many plants. In all years 36 seeds/m2 were needed for the latest sowing date.

Ploughing-in the seed gave an average benefit to grain yield, relative to conventional drilling, of 0·3 t/ha but the benefit increased to about 2 t/ha for the latest sowing for the 1986 harvest.

The earliest sowing advanced flowering date by 2 weeks relative to the latest but did not affect harvest date. Early sowing did not increase susceptibility to winter kill and only slightly increased the risk of chocolate spot disease (Botrytis fabae Sard.).

In all years the largest yields came from combinations of treatments which led to about 35–50 pod-bearing stems per m2 at maturity. The best combinations of treatments gave grain yields of 5·6, 50 and 62 t/ha in the 3 years respectively. These reflect the benefits of correct combinations of agronomic treatments and were probably also the result of good control of pests and pathogens.

Winter wheat grown following potatoes on a sandy loam at Woburn in 1978–9, 1980–1 and 1981–2 was compared with that on a clay loam at Rothamsted in 1978–9 and 1980–1, and on a silty clay (alluvium) at Woburn in 1981–2. The cultivar was Hustler in the harvest years 1979 and 1981 and Avalon in 1982. On each soil in each year multifactorial experiments tested effects of combinations of six factors, each at two levels.

The best 4-plot mean grain yield ranged from 89 to 11·1 t/ha during the 3 years; it was smaller on the sandy soil than on the clay soil in 1979, but larger on sand than on the clay in 1981 and 1982. Until anthesis the number of shoots, dry weight and N content of the wheat giving these best yields were less on sand than on clay. Unlike grain weight, straw weight was always less on sand.

Sowing in mid-September instead of mid-October increased grain yield on clay in each year (by 0·4·0·7 t/ha) and increased yield on sand only in 1981 (by 1·6 t/ha). Early sowing always increased dry weight, leaf area, number of shoots and N uptake until May. The benefits were always greater on clay than on sand immediately before N fertilizer was applied in the spring and usually lessened later on both soils.

Aldicarb as an autumn pesticide increased grain yield of early-sown wheat on both soils in 1981 by lessening infection with barley yellow dwarf virus. Aldicarb increased yield on clay in 1982; it also decreased the number of plant parasitic nematodes.

Wheat on sand was more responsive to nitrogen in division, timing and amount than was wheat on clay. In 1979 yield of wheat on sand was increased by dividing spring N between March, April and May, instead of giving it all in April, and in 1982 by giving winter N early in February. In 1981 division and timing on sand interacted with sowing date. Yield of early-sown wheat given N late, i.e. in March, April and May, exceeded that given N early, i.e. in February, March and May, by 1·4 t/ha; single dressings given all in March or all in April also yielded less than the late divided dressing. Yield of later-sown wheat given all the N in April was at least 1·2 t/ha less than with all N given in March or with divided N. In all years treatments that increased yield usually also increased N uptake. Grain yield on clay was never affected by division or timing of spring N or by application of winter N. This was despite the fact that all treatments that involved a delay in the application of N depressed growth and N uptake in spring on both sand and clay. The mean advantage in N uptake following early application of spring N eventually reversed on both soils, so that uptake at maturity was greater from late than from early application. Increasing the amount of N given in spring from the estimated requirement for 9 t/ha grain yield to that for 12 t/ha increased yield in 1982, especially on sand. The larger amount of N always increased the number of ears but often decreased the number of grains per ear and the size of individual grains.

Irrigation increased grain yield only on the sandy soil, by 1·1 t/ha in 1979 and by 07 t/ha in 1981 and 1982. The component responsible was dry weight per grain in 1979 and 1982, when soil moisture deficits reaching maximum values of 136 and 110 mm respectively in the 2 years developed after anthesis; the component responsible was number of ears/m2 in 1982 when the maximum deficit of 76 mm occurred earlier, in late May.

Ninety 4-month-old wether lambs were allocated to an initial slaughter group (n =10) or to one cell (n= 5) of a 4 × 4 factorial treatment design involving four levels of infection with Ostertagia circumcincta (0, 1000, 2000 and 4000 larvae/day) and Trichostrongyluscolubriformis (0, 1000, 2000 and 3000 larvae/day). They were maintained indoors in individual pens and offered freshly cut ryegrass-white clover herbage during an 84-day period of infection after which they were slaughtered. Body protein, fat, water, Ca and P contents were determined. Feed digestibility was determined in all sheep during 5-day periods during weeks 2, 5, 8 and 11. Faecal egg counts were determined and blood samples obtained at intervals and total worm counts done at slaughter.

The effects of mixed infection on feed intake and body-weight gain were multiplicative. Mean D.M. intake of sheep infected simply with 3000 larvae of T. colubriformis or with 4000 larvae of O. circtimcincta was reduced by 10 and 8% respectively, but in those infected simultaneously intake was reduced by 30%. Energy retention was depressed mainly by reduction in gross efficiency of use of metabolizable energy in infections with T. colubriformisand by reduction in feed intake in infections with O. circumcincta. The additional effect of mixed infection occurred mainly through further depression in feed intake.

There was no interaction between infections in effect on deposition of Ca or P in the body, both species having significant effect. Infection with T. colubriformis caused hypophosphataemia and hypocalcaemia, but infection with O. circumcincta had no effect.

The number of worms established by the infections was generally low compared with previous studies with conserved and concentrate feeds. This was associated with relatively low pathogenicity in infection with O. circumcincta and normal pathogenicity with T. colubriformis.

Infection with T. colubriformis reduced the number of adult worms of O. circumcincta present at slaughter.

Field experiments were conducted at the Punjab Agricultural University, Ludhiana from 1980–1 to 1984–5 to study the response of lentil genotypes to phosphorus application and Rhizobium inoculation. The number and dry weight of nodules increased consistently with increasing rates of application of phosphorus from 0 to 60 kg P2O5/ha. Nitrogenase activity of intact root nodules increased from 17 530 to 22 390 nmol/h per g dry weight of nodules with 20 kg P2O6/ha and to 27391 and 29170 nmol/h per g with 40 and 60 kg P2O5/ha, respectively. Rhizobium inoculation also increased nodulation, nitrogenase activity and grain yield. Interaction between phosphorus and Rhizobium inoculation was significant in 3 out of 5 years, indicating that the combination of Rhizobium and 20 kg P2O6/ha gave yield equivalent to 40 kg P2O6/ha without Rhizobium.

All combinations of four harvesting treatments and two sowing dates were compared in each of 2 years in field experiments near Nicosia. In one of the years, two levels of applied nitrogen were compared. The harvesting treatments were: (1) a milk-stage cut, (2) a boot-stage cut and a regrowth cut, (3) a grazing-stage cut and a regrowth cut, and (4) three grazing-stage cuts and a regrowth cut. The sowing dates were (1) normal (12 November) and (2) early (15 October), with sufficient irrigation to ensure establishment.

Applied nitrogen had virtually no effect on leaf growth, evidently because of high reserves of available nitrogen in the soil. Early sowing increased the rates of leaf emergence, extension and expansion up to the time of the first ‘grazing’ cut (when the first node was showing) and reduced the number of leaves which died in that period. Where growth was uninterrupted to the milk stage, early sowing did not affect the number of leaves produced by a main stem or primary tiller, but increased the longevity of the later leaves. Where there were three ‘grazing’ cuts, early sowing allowed time for the production of more and larger leaf blades, with longer sheaths, between the third 'grazing’ cut and the final harvest.

The ‘grazing’ cuts considerably reduced the rates of extension and expansion and the final size of the leaves which emerged soon after a cut. There was good recovery subsequently, however, in rates of extension and expansion and final leaf size, particularly with October sowing.

During almost all the period of leaf production on a main stem or primary tiller, several leaves (up to six) were expanding at the same time. The stage, during the period between emergence and death, at which a leaf blade reached its full length was typically half-way between emergence and death. Where growth was uninterrupted, area per leaf blade was positively correlated with both the number of days between the emergence of successive leaves and the number of days between emergence and death.

Dry weight, nutrient content and other properties of winter wheat were measured from anthesis to maturity between 1969 and 1984. From 1969 to 1978 the cultivar Capelle- Desprez was grown either as a first wheat, in the rotation potatoes, beans, wheat, or as a second wheat, in the rotation fallow, wheat, wheat. From 1979 to 1984 the cv. Flanders was grown in the rotation fallow, potatoes, wheat and in this period the wheat was given fungicide sprays. Grain yield of Cappelle-Desprez grown as a first wheat was greater with 96 than with 144 kg N/ha in spring. First wheats yielded much more than second wheats with 96, but not with 144 kg N/ha. Second wheats had more eyespot and take-all, but less mildew, than first wheats. Mildew was more severe with the larger amount of N. Grain yield of Flanders as a first wheat was greater than that of Cappelle-Desprez. Yield of Flanders was greater with 144 than with 96 kg N/ha and it was greater still on plots given 96 kg Nha plus 35 t/ha farmyard manure. Other properties in addition to grain yield were changed by cultivar, rotation and manuring.

Examination of the variation between years showed relationships among properties and between some of them and grain yield. Many of the relationships were independent of cultivar or husbandry. Relationships between weather factors and some properties, but not grain yield, were detected. Grain yield of first wheats was closely related to number of grains/m2, but the relative importance of number of ears/m2 and number of grains per ear varied from year to year. Yield was positively related to dry weight per grain in Flanders, but negatively in Cappelle-Desprez. The weight of straw was usually less than that of the total above-ground crop at anthesis, but varied between years in a similar manner. The amount of N in grain plus straw was generally well related to the amount of N in the wheat at anthesis, although the changes in N content after anthesis ranged from a loss of 9 kg/ha to a gain of 51 kg/ha. The uptake of N, P and K was more closely related to dry weight than to nutrient concentration.

Variation between years in the proportion in the ear of 14C supplied to the flag leaf was similar to that of 14C supplied to the next lower leaf, but was different for 14C supplied before and after anthesis, and did not relate to other properties.

Date of anthesis ranged from 7 June to 5 July. A model incorporating responses to photoperiod, vernalization and temperature accounted for 78% of the variance in date of anthesis. The duration of the period from anthesis to leaf senescence ranged from 33 to 60 days and was linearly related to mean temperature above a base of 7·5 °C. Dry weight per grain was negatively correlated with mean temperature between anthesis and leaf senescence; a relationship including an adjustment for number of grains/m2 fitted both cultivars.

The amount of N in grain plus straw and percentage of N in grain dry matter were decreased by increased rainfall during the 3-week period following the application of N fertilizer in spring. An additional 10 mm of rain decreased N uptake by 2–8 kg/ha and N percentage by 0·055. N uptake in grain plus straw decreased with progressively later sowing. Grain N% was positively correlated with temperature and with radiation during parts of the period of grain growth, but only 10% of the variance was accounted for by the combined effects.

Experiments with seed advancement and devernalization identified treatments which both increased rate of emergence and establishment and decreased bolting. Treatment temperature and duration were more critical for devernalization than for improving establishment. Exposing seeds to 15 °C for 6 days (at restricted moisture availability to prevent premature germination) sometimes promoted slight devernalization but sometimes enhanced bolting; 20 °C for 3 days had little effect whereas 20 °C for 6 days was moderately effective. The best treatment for both improving establishment and decreasing bolting was to steep the seed in water for 3 h at 25 °C, dry it to between 115 and 120% of its original air-dry weight, store it for 4 days at 25 °C and then air dry.

Results in 1985 showed that the improvements are insufficient to allow sowing as early as 1 March. Following sowing on 17 March 1986, seed advancement increased establishment for two bulks of seed from 54 to 76% and from 63 to 77% respectively while bolting was decreased from 9·1 to 1·2% and from 5·9 to 0·7%. This suggests that in future it may be possible to recommend that sowing starts about a week earlier than at present.

The results also suggested that only a previous vernalizing experience could be reversed. There was no indication that a devernalizing stimulus could be stored by seeds and used to offset the effects of cold after sowing. However, the best treatment in 1985 would have reversed a much more severe vernalizing stimulus than that likely to be encountered by the seeds while on their mother plant.

The relation between the dry-matter degradability (DMD) of different cultivars of barley straw and their colonization by rumen micro-organisms was studied in incubations of straw with the mixed population in situ and with pure cultures of rumen bacteria in vitro. The total attached population in situ was quantified by particle-associated i glutamate dehydrogenase (GDH) activity, while the cellulolytic population was assessed by bound carboxymethylcellulase (CMCase) activity. CMCase reached a peak between 24 and 36 h incubation, and the peak activity was highly correlated with DMD between 24 ) and 96 h. After 36 h, CMCase activity declined, particularly with the more degradable (varieties. GDH continued to increase after 36 h and had no relation to DMD. The adhesion of pure cultures of both cellulolytic and non-cellulolytic bacteria was measured i turbidimetrically in a 30 min incubation. No relation was found between DMD and the extent of adhesion by any of Ruminococcus flavefaciens, Bacteroides succinogenes, Butyrivibrio fibrisolvens or Selenomonas ruminantium. It was concluded the rate of degradation of straw is not determined by the initial rate of attachment of cellulolytic micro-organisms, but by the way in which colonization subsequently develops after attachment takes place

The expression of symptoms of stem nematode reproduction on a total of 53 white clovers (26 cultivars, 14 genepools and 13 introductions from plant collections) was studied in a series of field and glasshouse experiments. Seedlings or stolon-tip cuttings were inoculated with nematodes and the clovers classified by the proportion of plants which developed symptoms. Significant differences were found between varieties although in each test the majority was intermediate between more resistant and susceptible extremes. There was significant positive correlation between tests, in spite of different inoculation methods and different average levels of susceptibility. Very large-leaved cv. Aran was more resistant than most other clovers tested, and small-leaved cv. S. 184 was more susceptible. There was no general correlation of leaf size with reaction to stemnematode. Small-leaved cv. Pronitro was also resistant while several large-leaved cultivars were susceptible. In observations of plants exposed to nematodes over a long period, either by sequential inoculations or through perpetuating latent infections, apparently resistant plants eventually succumbed and supported nematode reproduction. It has not been determined whether this was because selection for virulence in the nematodes had occurred.

The intercropping of Azolla pinnata (Vietnam) with rice varieties transplanted in rectangular (40×10 cm) and double-narrow-row (15 × 10:65–80 cm) spacings showed faster growth and nitrogen fixation than in square (20 × 20 cm) spacing with the same number of hills per unit area. Inoculation of 2·0 t/ha fresh Azolla, 10 and 30 days after transplanting, produced Azolla mats on the water surface 25 and 50 days after transplanting, respectively. The total fresh biomass of Azolla grown with different rice varieties in square spacing was 26·7–33·0 t/ha; this produced 41·9–61·3 kg N/ha. However, rectangular and double-narrow-row spacing produced 28·7–37·7 and 34·4–39·6 t/ha fresh Azolla containing 53·9–69·0 and 58·0·73–3 kg N/ha, respectively if the rice rows were transplanted in north-south direction and 36·3–41·5 and 40·0–43·7 t/ha fresh biomass containing 63·4–74·2 and 65·3–83·3 kg N/ha, respectively in east-west direction.

The grain and straw yields of rice grown in rectangular and double-narrow-row spacing with north-south row orientation were lower than the yields of rice in square spacing, but the east-west row orientation of these spacings showed yields similar to those obtained by growing rice in square spacing.

Legumes like Aschynomene, Neptunia and Sesbania possess nodules on their stems in addition to those on the roots (Barrios & Gonzelez, 1971; Dreyfus & Dommergues, 1981) and have the ability to grow under water. The most distinctive characteristic of all stem nodulating legumes in the presence of predetermined nodulation sites on the stem, the formation of which is independent of Rhizobiwm infection (Arora, 1954; Subba Rao, Tilak & Singh, 1980).

Two experiments were carried out to examine the value of copper, cobalt and selenium contained in soluble glass boluses as a means of providing supplementary trace elements to goats.

In the first experiment 36 purebred Toggenburg goats were used and divided into two groups. One group was treated with soluble glass boluses while the other was left as control.

In the second experiment 46 Saanen half-bred goats were used, divided into three groups. The first group was treated with soluble glass boluses, the second was treated with selenium injectable compound and the third was left as control.

Blood samples were collected on four occasions, during an experimental period of almost 12 months and plasma copper, serum vitamin B12 and blood selenium concentrations were determined. All those measurements showed significant increases for about a year, and were due to treatment. The advantages of glass boluses were not shared by the selenium injectable compound.

The influence of dietary nutrients on carcass composition, rate of tissue deposition and the development of specific tissues, major and minor muscles in particular has been well documented for pigs reared in a temperate environment. Attempts have also been made in this environment to simulate artificial tropical conditions and, on the consequence of such conditions, to predict the nutrition and growth of the pigs.

All combinations of four levels of potassium and two of nitrogen were applied in each of 2 years to a hill sward on a brown podzolic soil with an 8 cm peaty surface horizon anda very low level of extractable K. The sward had been surface-sown 11 years before with white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.). During the course of the experiment, harvesting was by cutting, with an average interval between cuts of 5 weeks. The previous management had been sheep grazing.

The proportion of clover in harvested herbage was increased by applied K and reduced by applied N. The clover grew strongly in the 1st year of cutting management where K, but no N, was applied, but there was much less clover in the 2nd year on all plots. The concentration of K in both clover and grass was greatly increased by applied K, but only the clover responded strongly in terms of extra herbage produced. This suggests that grass growth was N-limited, whereas the clover had sufficient N from symbiotic fixation.

Applied K increased the size and weight of clover leaves, the rate of extension of the stolon main axis, and the number and length of stolon branches, but did not affect the rate of emergence of leaves on the stolon main axis. Applied N had a generally negative effect on the aspects of clover growth and morphology which were measured. The length and weight per ryegrass leaf blade were generally slightly increased by both applied K and applied N.

Calves were fed continuously at 4 h intervals a low P basal diet with or without P supplementation to give three levels of dietary P intake: one was deficient in P (2·5 g/day), the second adequate (6·0 g/day) and the third contained an excess of P (10·0 g/ day) according to Agricultural Research Council (1980) recommendations. Once steadystate conditions were achieved (after 2–3 weeks on the diet) 32P and 46Ca kinetic studies were carried out, together with measurements of P flow rates at the reticulorumen and P and Ca balances. With increased dietary P intake, the amount of dietary P absorbed increased as initially did the efficiency of P absorption. Both the serum P concentration and the rate of P retention increased in direct relation to increased P intake and increased P absorption. Salivary secretion of P increased with increased P absorption and in direct relation to serum P concentration. Endogenous faecal losses of P were also directly related to P intake and P absorption and results suggest that increased loss with increased P intake is inevitable.

Despite a constant and adequate Ca intake, the rate and efficiency of Ca absorption, which was low on the low-P diet, increased significantly on the adequate and high-P diets. Similarly, Ca retention increased substantially on the higher P diets, showing that Ca metabolism can be controlled according to P status.