It is suggested that the covariance method of statistical analysis is of considerable value in correcting for uncontrolled inequalities arising early in an experiment, and in analysing the effects of developmental factors on yield. As an example its application to the results of an experiment with beans is described.

It is with great pleasure that the writers acknowledge their indebtedness to Dr J. Wishart for his helpful criticism throughout the work.

Nitrogen fixing, free-living, organisms like Azotobacter and Azospirillum are known to increase the nodulation and efficiency oiRhizobium (Krasilinikov & Korenyakov, 1944). The beneficial effect of incorporation of Azotobacter with Rhizobium may be due to the production of auxins (Vancura & Macura, 1960) and prolonged survival of Rhizobium in the presence of a large amount of polysaccharide gums (Krasilinikov & Korenyakov, 1944). In green gram (Vigna radiata L. Wilczek), because of high temperature and unavoidable soil moisture stress during hot and dry summer months (April-June), survival of the seed-inoculated Rhizobium is very poor (Lai, Dubey & Chandra, 1983). In the present study attempts were made to improve the efficiency cf Rhizobium as an inoculant by the use of Azotobacter chroococcum and Azospirillum brasilense.

The F1 and F2 generations of a diallel cross of six-row barley involving the parents, Beecher, Athenais, Atlas 46, 3130-4564-3, and 3130-864-4 were studied and heterosis, inbreeding depression, and combining abilities were measured for grain yield, number of tillers per plant, number of kernels per plant, kernel weight, and plant height. Significant heterosis was detected for grain yield in two of the ten crosses, for number of tillers per plant in one cross, for number of kernels per plant in two crosses, for plant height in three crosses, and for kernel weight in none of the crosses. The inbreeding depression of the F2 generation was present in most cases but significantly so in a few. Atlas 46 x 3130-4564-3 exhibited inbreeding depression for grain yield, number of kernels per plant, and plant height.

The general combining ability (GCA) mean squares of both generations were significant for all characters studied except number of kernels per plant in the F1 generation. The specific combining ability (SCA) mean squares were significant for only plant height in the F1 generation and all characters studied except number of tillers per plant in the F2 generation.

The GCA effects indicated that Beecher and Athenais are good general combiners for grain yield and its components. The latter parent produced good yielding hybrids with slightly shorter plants than the remaining hybrids.

The SCA effects revealed that Athenais × 3130-4564-3, Athenais × 3130-864-4, and Beecher × Atlas 46 seem good specific combinations for high grain yield. Also, the former two crosses tend to produce shorter plants.

(1) The skeletons of young pigs on a ration composed mainly of cereal grains but with the addition of cod-liver oil show a very distinct lack of calcification, the percentage of ash being about 12 per cent. lower than in the bones of normal animals.

(2) Calcification of the bones proceeds up to maturity. A difference of about 360 gm. tricalcic phosphate was found between the same mature bones of normal and calcium-deficient animals.

(3) The ratio of lime to phosphate is almost the same in the different bones of the same individual as well as in the normal and rachitic bones of swine. The main characteristic of the bones in low-calcium rickets is a low-ash content, but the composition of the ash is normal.

This study investigated whether the interaction of protein level and grain type can affect milk production, nutrient digestibility and rumen fermentation in primiparous Holstein cows. Four dietary treatments were used: high-protein with barley as the only grain source, HP-B; (2) high-protein with an equal mix of barley and maize, HP-BM; (3) low-protein with barley as the only grain source, LP-B and (4) low-protein with equal proportions of barley and maize, LP-BM. High-protein diets showed no improvement in milk or protein yield compared with low-protein, but barley and maize mix diets increased energy-corrected milk yield and fat yield compared with barley-only diets. The highest total apparent digestibility of dry matter, organic matter and neutral detergent fibre was observed for LP-BM whereas HP-BM showed the greatest crude protein digestibility. Treatment had no effect on total volatile fatty acid concentrations, molar proportion of acetate and propionate and acetate to propionate ratio. The lowest ruminal pH was observed for LP-B. High-protein diets resulted in greater concentrations of ammonia nitrogen (N), urinary N, blood and milk urea nitrogen compared with low-protein diets, whereas low-protein diets showed better nitrogen utilization efficiency. This study showed that primiparous lactating cows do not benefit from high-protein diets with different fermentation rates of grain sources, but barley and maize diets may improve milk production performance, ruminal fermentation and pH under the present dietary conditions. The current results on milk production performance should be interpreted with caution due to the small number of cows used (eight in each treatment).

Bahia grass (Paspalum notatum Flugge) plants were grown in growth chambers at Gif, France, and at Gainesville in Florida, demonstrating that the species is a long-day plant and greatly influenced by light quality during the photosynthetic period. Flowering occurred in all instances when the middle of the dark period was interrupted with red or red + far-red light. With nightly interruptions of farred light, flowering occurred only when a sufficient quantity of far-red was present during the photosynthetic period. Plants grown under short days with nightly interruptions of red, far-red or red + far-red light had less starch accumulation and greater leaf growth and dry weight than plants grown without nightly light interruptions, whatever the light quality during the photosynthetic period. The treatments did not affect the partitioning of assimilates and flowering in the same way.

An experiment was conducted to evaluate whether dietary reduction and sex class affect nutrient intake, digestibility, purine derivative (PD) excretion and heat tolerance coefficient in lambs. Thirty-five hair lambs (14.5 ± 0.89 kg initial body weight (BW), 2 months old) were used in a completely randomized study with a 3 × 3 factorial arrangement, three sex classes (11 intact males, 12 castrated males and 12 females) and three levels of feeding (ad libitum, 300 and 600 g/kg/dry matter (DM) feed restriction) for 120 days. Intact and castrated males showed higher intakes of DM and neutral detergent fibre corrected for ash and protein (NDFap) than females. At 300 g/kg/DM feed restriction, NDFap digestibility was lower in intact males than in other classes; however, no differences were found between classes when subjected to ad libitum feeding or 600 g/kg/DM. The basal endogenous nitrogen and endogenous urinary losses were highest in intact males. Allantoin, uric acid and PD excretion, as well as PD absorption and microbial protein production were lowest in the animals subjected to 600 g/kg/DM feed restriction. Microbial protein synthesis (MPS) was highest in animals subjected to 600 g/kg/DM feed restriction. The lowest temperatures were observed in animals subjected to 600 g/kg/DM feed restriction. The heat tolerance coefficient was highest in animals subjected to 600 g/kg/DM feed restriction. In conclusion, feed restriction reduced the time spent on feeding and rumination but increased the digestibility of DM. The restriction level of 600 g/kg/DM maximized MPS and infrared thermography indicated an elevated heat tolerance coefficient.

We investigated whether the one-time application of polymer-coated urea (PCU) before transplanting could simultaneously improve the grain yield and nitrogen use efficiency (NUE) of japonica-indica hybrid rice (JIHR) through a field experiment. The local high-yield JIHR cultivar Chunyou-927 was field grown during the rice-growing seasons in 2019 and 2020. The experiment consisted of three treatments: no nitrogen application (0N), application of conventional urea (CU), and the one-time application of PCU. Grain yield was 1.0–1.3 t/ha higher, and agronomic NUE (kg grain yield increase per kg N applied) was 5.2–5.9 kg/kg higher, respectively, under the PCU treatment compared with the CU treatment across the two study years. When compared with the CU treatment, the PCU treatment could (1) improve root morphological trait, (2) reduce redundant vegetative growth during the early growth period, (3) increase matter production during the mid and late growth period, and (4) increase plant activity during the grain-filling period. Overall, our findings indicate that one-time PCU application before transplanting of the JIHR cultivar holds great promise for increasing grain yield and NUE.

Soils in the green-house are exposed to conditions that are admittedly more or less artificial. The range of temperature and moisture is not the same as that in field soils, while the aeration of green-house soils is, if anything, even more artificial. The artificial conditions are emphasized still more strongly when the soil is kept in small pots. The operations incident to the filling of the pots and the applications of fertilizers involve a more intimate contact of the soil particles with atmospheric oxygen than is possible under field or garden conditions. This leads to an abnormal multiplication of the soil bacteria and to a consequent abnormally rapid oxidation of the organic matter. In the course of time the more readily decomposable portions of the organic matter in the soil become depleted and this is followed, in turn, by a decline in the numbers of bacteria that will grow on agar plates. It is possible that the rapid falling off in numbers is due not merely to the depletion of the readily decomposable organic matter, but also to the accumulation of certain cleavage products injurious to the bacteria. Of the latter factor we have no direct knowledge and it is referred to in this place only as a possible explanation of the facts recorded below. It may be added here, also, that the greatly decreased number of bacteria appearing on agar plates should not be accepted as absolute proof that the total number of microorganisms in the soil had diminished. There is a possibility that a compensating increase had occurred of bacteria that do not grow on agar plates, as for instance, the nitrous and nitric ferments, etc.….

Studies were conducted to evaluate the effect of 50% restriction of normal daily water intake on nitrogen balance, plasma urea concentration and excretion of different urinary nitrogenous constituents (ammonia, creatine, creatinine, urea and undetermined nitrogen) in the Marwari breed of sheep of the Rajasthan desert, India. The results indicated that the reduction in feed intake in water-restricted sheep leads to a reduction in intake and excretion of nitrogen through faeces (P < 0·01) and urine (P < 0·01) of these animals. No sigficant differences in the excretion of most urinary nitrogenous constituents between ad libitum watered and water-restricted animals were observed, except for creatine which was excreted in significantly higher concentrations in the urine of the water-restricted animals. On offering water ad libitum for 3 days to the restricted animals, the plasma urea in these animals dropped from 33·0 to 20·7 mg/100 ml, i.e. almost to the level in the animals watered ad libitum (18·7 mg/ 100 ml). The daily dry-matter intakes of the ad libitum watered and restricted animals were 790 and 488 g, respectively. The digestibility coefficients for dry matter and crude protein of the feed were 47·1 and 27·2%, respectively in ad libitum watered and 56·6 and 39·5%, respectively, in restricted animals. This improvement in the efficiency of digestion in water-restricted sheep may not be due to any enhanced microbial activity in the rumen, but may possibly be due to an increased absorption of feed nutrients in the hind gut of these animals.

The effects of season and altitude on floral initiation of two Trifolium repena L. cultivars, Haifa and California Ladino, were tested in the area of Ayacucho, Peru (2730 m, 13° S), with regard to their seed production potential. Specific effects of daylength at a constant temperature (20 °C) were examined in growth chambers.

In Ayacucho, the proportion of inflorescence-bearing nodes was found to be lowest between December and June (Haifa 10–20%, Ladino 0–10%) and highest in August (Haifa 30%) and September–October (Ladino 15%). Late in the cool season, floral initiation of Ladino, but not that of Haifa, increased strongly at a high altitude (3250 m). In growth chambers, Haifa initiated few inflorescences and Ladino none in a 10 h daylength. In 16 h, the floral initiation of Haifa was very limited but Ladino formed many inflorescences. Floral initiation of Haifa was most pronounced and lasted longest after a daylength shift from 10 to 13 h.

It is concluded that seasonal and altitudinal variations in low temperature were the main factors influencing floral initiation in the region of Ayacucho. Haifa is considered to be an intermediate-day plant, suited for seed production in the region because of its marked and early flowering. Ladino was classified as a quantitative longday plant, unsuitable for seed production at this low latitude because of its retarded floral response to low temperature.

Three preliminary experiments at Cambridge (1904–70) indicated that several varieties and breeding lines of sugar beet differed in their response to fertilizers. Three factorial experiments were therefore made at Broom's Barn (1970–2) to measure response by four widely differing varieties of sugar beet (Sharpe's Klein ‘E’, Maris Vanguard, V.T.137 and Anglo-Maribo Poly) to nitrogen (0, 75 and 150kgN/ha), sodium (0 and 250 kg N/ha) and potassium (0 and 400 kg K/ha) fertilizers. Increases in sugar yield from 75 kg N/ha by each of the varieties were remarkably similar and giving a further 75 kg N/ha neither increased nor decreased the yield of any variety on average over the three experiments. The yield response to sodium and potassium was greatest in Sharpe's Klein ‘E’ and least in V.T.137; however, as with nitrogen, varieties responded inconsistently from year to year and the interactions were not statistically significant for data pooled over the three experiments. These experiments indicate that varietal differences in fertilizer requirement are unlikely to be important in commercial practice.

Field studies were conducted at Ilorin and Bacita during the 1985–6 cropping season to evaluate the use of hexazinone [3-cyclohexyl-6-(dimethylamino)-l methyl-1, 3, 5-triazine-2, 4(1 H, 3H)-dione] alone, and in combination with diuron [3,(3,4-dichlorophenyl)l-l dimethyl urea] in crops of sugar cane. Hexazinone, alone or in combination with diuron, effectively controlled a broad spectrum of weeds in a loamy sand soil at Ilorin. Most of the herbicide rates used were, however, severely phytotoxic to the crop. On silty clay-loam soils at Bacita, the same herbicide treatments, while giving effective control similar to that obtained at Ilorin, were not phytotoxic to the crop. Weed control effectiveness was influenced by the percentage of organic matter in the soils and by the amount of herbicides used. A broader spectrum of weeds was controlled by the mixture of hexazinone plus diuron than by hexazinone alone. There was no difference between the performance of the tank and formulated mixtures of hexazinone plus diuron.

Data from the F1, F2 and F3 generations derived from four F1 hybrids of sunflower were analysed to determine the genetical control of eleven agronomically important traits namely, flowering time (FT), final height (FH), seed set (SS), fresh seed weight (FSW), dry seed weight (DSW), 25-seed weight (SSW), head diameter (HD), head angle (HA), neck width (NW), Botrylis infection (BI) and percentage oil content (PO), with the objective of assessing their potential for producing superior recombinant lines. Comparisons of means revealed significant differences between the F: generations of crosses for all the characters except FT. Model fitting indicated that these differences were attributed either to variation in the magnitude of the dominance component [h], or the projected mean of the Finfin; generation, m. Further, all the variation in the generation means was accounted for by the m and [h] parameters and epistasis was shown to be non-existent for almost all the traits. Analysis of the second degree statistics revealed the presence of additive genetic effects and most of the characters showed moderate heritability except for HD, which was highly heritable. All the crosses were predicted to produce significant numbers of transgressive segregants and consequently were expected to yield superior inbred lines and second cycle hybrids either to be released as varieties as such or to be utilized in future breeding work. The overall differences between the crosses, however, were not highly pronounced and therefore it was not possible to identify a cross which would yield markedly superior recombinant lines and F1 crosses compared to the others.

Much of the recent increase in crisp lettuce production in the U.K. has been marketed as heavily trimmed solid ‘Iceberg’ heads, wrapped in plastic film. Supermarkets want ‘Iceberg’ lettuce with a minimum trimmed weight of 450 g (Anon. 1983) and consistency of product, but the mean head weight of crisp lettuce at maturity can vary considerably from one sowing to another as a result of environmental conditions earlier in growth (Pew, Gardner & Bessey, 1984; Wurr & Fellows, 1984). In midsummer, some sowings of the most popular variety Saladin can produce larger and heavier heads thanc supermarkets require and the cause of this variation needs to be understood in order to increase the proportion of crops meeting supermarket needs.

The conclusions that have been arrived at from the foregoing statistical examination of the available data on the physical properties of the Natal soils used by Coutts are:

(1) The base exchange capacity of the soil, as measured by Schofield's potassium phosphate buffer method, appears to be of predominant importance for predicting several of the soil properties, as for example the sticky point and the moisture content at 50 per cent. relative humidity. On the other hand, the clay content seems to be of quite minor importance in predicting these soil properties.

(2) The information from the data supplied by the Keen-Raczkowski box indicates that ω, the weight of water held per gram of soil in the box is very closely correlated with the base exchange capacity of the soil, while the swelling and pore-space parameters are more complex. The swelling υ seems to be dependent on the base exchange capacity of the soil and a term probably representing the structure of the soil, while the pore space p seems to be dependent on the clay content and a soil structure term. By choosing an appropriate definition of the pore space practically all the structure information given by the swelling parameters is contained in it.

1. Considerable differences were found in the specific conductivities of different soils at any one time of the year, and considerable differences in any one soil at different times of the year, the specific conductivities being highest in March and lowest in June and July. Hence it is only possible to compare different soils when samples of these soils are taken at the same time of the year.

2. A relation has been found between the specific conductivities of the soil extracts and the mean weights of lint per plant per row in the case of 2 strains of Ishan cotton. Other data are presented showing that the specific conductivity of a 1 to 5 soil extract is an index of the fertility of the soil.

3. It has been found that the specific conductivity of a soil decreases under continuous cultivation. There is evidence that the rate of solution also decreases under the same condition.

The effects of six amounts (0, 17, 34, 51, 68, 85 kg N/ha) of fertilizer N, applied at sowing time, on the crude protein (N × 6·25) content of barley grain sown as the first, second and fourth or later tillage crop after grazed pasture were studied over three seasons at a total of 126 sites. In addition, non-protein N in the grain was measured at 24 sites.

The overall crude protein content was 11·3% without N, increasing to 13·4% with 85 kg N/ha. The first increment of 17 kg N/ha gave the least increase in grain protein content. The year which gave the largest yields gave the lowest grain protein contents and vice versa. The mean grain protein contents without N for 1971–3 inclusive were 10·8, 11·5 and 11·8% respectively.

The mean grain protein contents without N when barley was sown as the first, second and fourth or later tillage crop after pasture were 12·6, 11·5 and 10·0% respectively; the corresponding values with 85 kg N/ha were 14·4, 13·9 and 11·8%. There was a positive relationship between grain protein content and lodging, especially in barley sown as the first tillage crop after pasture, where lodging was most severe.

Non-protein N was low and only accounted for 5–8% of the total grain N content. The mean grain. N uptake with no fertilizer N applied was 82, 70 and 49 kg/ha in barley sown as the first, second and fourth or later tillage crop respectively. The apparent recovery of fertilizer N was largest in fourth or later barley.

1. Two lots of twenty sheep each were fed indoors on rations known to produce satisfactory growth. The calorific value of the two diets was the same. One lot received 52 per cent, more digestible protein than the other. The diet of the low protein group was protein deficient according to the calculations of Wood.

2. The sheep were shorn at the beginning of the experiment and again at its conclusion. Fibre measurements were made on samples taken at the same two periods from the same body area. The fleece and fibres grown during the experimental period were compared in each case with the fleece and fibres grown during the pre-experimental period. The fibre measurements included fineness, length and fibre weight.

Experiments are described which analyse the effects of date of sowing and of a black petroleum soil mulch on the growth of two maize hybrids. The two hybrids used were Anjou 210, which is late maturing in S.E. England, and Kelvedon 75A, which is an early hybrid.

As sowing was delayed from mid-April until the end of May, so there was a greater development of vegetative tissue (mainly stem) and leaf area which reached peaks at a later stage after silking. In Anjou 210 early sowing led to higher grain yields (12%) as the production of peak vegetative weight near to the time of silking allowed dry matter produced after that stage, still at a time of high radiation, to move direct to the oars. Also, the remobilization of the secondary source of grain dry matter, namely previously stored photosynthate from the stem, occurred earlier with early sowing and to a greater extent when a longer grain-filling period was allowed.

The hybrid K 75A had a lower vegetative weight, and earlier silking coincided with higher levels of radiation, and the resultant increase in net assimilation rate led to a higher proportion of dry matter being partitioned into the ear. Because this hybrid flowered and senesced early, reserves of stem carbohydrate were low and the time available to transfer carbohydrate to the ear was short, resulting in lower yields than in the later maturing Anjou 210. K 75A also responded unexpectedly to the sowing treatments. Although late sowing gave higher grain yields in both hybrids up to 156 days after sowing, in the case of K 75 A, the early senescence curtailed the continuation of grain fill that would normally give early sowing an advantage and hence the late sown K 75 A produced 10 % more grain.

The application of a black petroleum mulch to the surface of the soil to raise soil temperature enhanced the benefits derived from early sowing. Plants given this treatment produced greater leaf areas and vegetative dry weights. As a result more carbohydrate was translocated from the stem during the grain-filling period, increasing grain yield by 13% following an increase in both number of grains and individual grain weight.