Showing papers in "The Journal of Agricultural Science in 1989"
TL;DR: Field experiments comparing 13 winter wheat varieties representing very old, old, intermediate and modern groups were carried out over three seasons, and the genetic gain in yield measured is compared with those estimated for other countries.
Abstract: Field experiments comparing 13 winter wheat varieties representing very old, old, intermediate and modern groups were carried out over three seasons. The experimental sites were on soils of high fertility and weeds, diseases and pests were controlled by applications of proprietary agrochemicals. Lodging was prevented by supporting the plants with coarse-mesh netting.The average yield of all varieties over the three harvest years 1984, 1985 and 1986 was 7·7 t/ha (at 15% moisture content). Compared with the very old varieties which were grown by farmers during the 19th century, the modern varieties gave 59% more grain, had 14% more ears/m2 and 30% more grains per ear, but a similar mean grain mass. The modern varieties yielded slightly more biomass (total above-ground dry matter at harvest), were much shorter and reached anthesis about 6 days earlier than the older ones. In 1984, when the yields were greater than in 1985 and 1986, the yield advantage of the modern varieties was more in percentage and absolute terms than in the other years. Also, in 1984, the differences between the very old and the modern varieties in biomass was the greatest.The genetic gain in yield measured in these experiments is compared with those estimated for other countries and reasons for the variation are discussed.
249 citations
TL;DR: The book shows the sorts of factors that should be considered before governments interfere with established activities in the United States and should be read by agriculturalists since afforestation and deforestation have important effects on agriculture and control of the former has many implications for the latter.
Abstract: ment intervention in the United States, is to be welcomed. After an Introduction, there are chapters on State forest practice Acts, cost sharing and technical assistance programmes, price-reporting services, minimum wage and occupational safety and health regulations, the Jones Act (which restricts shipments between USA ports to USA-built, -owned and -operated vessels), taxation, and public ownership of forestlands. The book ends with a chapter giving a summary, conclusions and policy implications. Each chapter analyses economic and social effects in a fairly rigorous way but, as the authors point out many times, they are constrained by inadequate data. Nevertheless, the book shows the sorts of factors that should be considered before governments interfere with established activities. It should be read by agriculturalists since afforestation and deforestation have important effects on agriculture and control of the former has many implications for the latter. Agricultural scientists need to think ahead so that the land resources of the world can be used to best advantage.
188 citations
TL;DR: The fluxes of NH3-N from the grazed swards were greatest whilst the animals were present and there were large differences between treatments, the ratio of total NH3 losses from 420 N grass to those from 210 N grass and grass/lover being 7·8:1.
Abstract: Ammonia (NH3)-N fluxes from three swards, grazed by cattle and with different N managements, were measured using the mass balance micrometeorological method after a 7-day grazing period in the spring of 2 years. At the same time the impact of the sward managements on N returns in dung and urine was examined in housed animals and the effects of the changes in excreted returns on NH3-N losses examined. The treatments were ryegrass swards receiving either 420 or 210 kg N/ha per year, and a mixed ryegrass/white clover sward receiving no mineral N. There was little difference in the faecal N returns between treatments but there were differences in the N returned in urine, thus 74, 60 and 56% of the excreted returns from 420 N, 210 N or grass/clover treatments, respectively, were in urine. The fluxes of NH3-N from the grazed swards were greatest whilst the animals were present and there were large differences between treatments, the ratio of total NH3 losses from 420 N grass to those from 210 N grass and grass/lover being 7·8:1. The NH3-N losses were equivalent (i) to 12,5 and 7 % of the urinary N returns to 420 N, 210 N grass and grass/clover swards, or alternatively (ii) to 9 and 3% of the fertilizer addition to 420 and 210 N swards and 3% of the estimated rate of N2 fixation in the grass/clover sward. Throughout the investigation there was little difference between the effects with the 210 N grass swards and those with grass/clover.
129 citations
TL;DR: In this paper, pig and cow slurries were acidified to pH values between 7 and 4 with 5 M H2SO4 and showed a significant positive correlation between the NH4+-N content of the slurries and the volume of acid required to attain a target pH of 6·0 for pig slurry and a pH of 5·5 for cow slurries.
Abstract: Pig and cow slurries were applied to bare soil surfaces in the laboratory. Volatilization of NH3 was measured using ventilated enclosures for 3·25 days after slurry application. Slurries were acidified to pH values between 7 and 4 with 5 M H2SO4. Lowering cow slurry pH to 5·5 decreased NH2 volatilization by 95%, while lowering pig slurry pH to 6·0 decreased NH3 volatilization by 82%. A field experiment, measuring the volatilization of NH3 for 2 h after application to grassland stubble of slurry acidified to pH values between 7·5 and 5, gave similar results to the laboratory study.Titration curves were constructed within the pH range of 9 to 4 with cow and pig slurries. There was a significant (P < 0·05) positive correlation between the NH4+-N content of the slurries and the volume of acid required to attain a target pH of 6·0 for pig slurries and a pH of 5·5 for cow slurries. One litre of slurry containing 2 g of NH4+-N required c. 20 ml of 5 M H2SO4 for acidification.
122 citations
TL;DR: It is demonstrated that AO has a marked effect on the microbial population and the stoichiometry of the rumen fermentation, and that these changes can be seen in an in vitro system.
Abstract: Frumholtz, P. P., Newbold, J., Wallace, R. J. (1989). Influence Of Aspergillus oryzae fermentation extract on the fermentation of a basal ration in the rumen simulation technique (Rusitec). Journal of Agricultural Science, 113 (2), 169-172.
99 citations
TL;DR: The prospects for improving crop yields through genetically modifying photosynthesis are assessed and the reasons why this is so are examined.
Abstract: There are no generally known instances where genetic improvement in crop yield has been attributed, by retrospective analysis, to improved photosynthesis Neither are there any cases where selection for improved photosynthesis has resulted in increased crop yield (…) The purpose of this review is to examine why this is so and to assess the prospects for improving crop yields through genetically modifying photosynthesis
80 citations
TL;DR: In this paper, the effects of the measured rates of loss on the input of NH 3 from grazed grassland to the atmosphere are discussed and the relationship between inputs and total losses and also between the concentration of N in the herbage and losses per animal.
Abstract: Total loss under continuous grazing was 61% of that under the rotational system. Although the losses represent only 7.8, 5.6 and 3.7% of the inputs to 420N, 210N and GC treatments, there was a good relationship between inputs and total losses and also between the concentration of N in the herbage and losses per animal. The effects of the measured rates of loss on the input of NH 3 from grazed grassland to the atmosphere are discussed
78 citations
TL;DR: These studies show that bone resorption, salivary P secretion, P absorption and urinary P excretion all play a part in P homoeostasis in the growing ruminating calf, and that the relative importance of each of these processes depends upon the P status of the calf.
Abstract: The mechanisms by which phosphorus homoeostasis is achieved in growing calves in response to changes in P supply ranging from deficient to excess were investigated in three studies in which additional P was given in the diet, infused into the abomasum, or infused directly into the blood.Whereas the rate of P absorption was directly related to P supplied, the efficiency of absorption of P differed according to the supply. Thus, the absorption efficiency was low from the P-deficient basal diets, increased with P supplementation until the supply was sufficient to meet requirements and then decreased at higher rates of P supply, possibly as a result of homoeostatic control.The serum P concentration, which was directly related to the rate of P absorption, appeared to determine the rates of P retention, salivary P secretion and urinary P excretion. Urinary P excretion was negligible at P intakes below those needed to supply requirements, and any additional P absorbed was partitioned between retention and salivary P secretion in the ratio 0–88:1, these two processes continuing to have equal priority for absorbed P until retention reached a maximum, approximately equal to the postulated growth requirement. Only when the growth requirement for P had been met, did urinary P excretion occur, increasing progressively as the serum P concentration exceeded the renal threshold.The endogenous faecal loss of P increased in direct relation to salivary P secretion and hence to the rate of P supply, the increase occurring even in P-deficient animals. This finding supports the claim that the inevitable endogenous faecal loss of P is not maintained at the constant rate expected at zero P intake until all requirements are met, as assumed by the Agricultural Research Council (1980) in their calculations of P requirements, but varies in direct relation to the P intake needed to supply a particular requirement. Indeed, these results suggest that the ARC (1980) recommendations for P, particularly for growing animals, are too low.Finally, these studies show that bone resorption, salivary P secretion, P absorption and urinary P excretion all play a part in P homoeostasis in the growing ruminating calf, and that the relative importance of each of these processes depends upon the P status of the calf.
72 citations
TL;DR: Growth and water use of kabuli-type chickpea was measured during the 1982/83 and 1983/84 growing seasons in northern Syria under rainfed conditions and comparison between seasons showed that the relations could not be used predictively.
Abstract: Growth and water use of kabuli-type chickpea was measured during the 1982/83 and 1983/84 growing seasons in northern Syria under rainfed conditions. Winter-sown (November) and springsown (March) crops of cv. ILC 482 were grown in 1982/83 while in 1983/84 spring-sown crops of contrasting genotypes (ILC 482, ILC 1929 and ILC 3279) were compared.In 1982/83, shoot dry matter and seed yields of the winter-sown crop were almost twice those of the spring-sown crop although the water use of both crops was almost the same. Root growth of both crops was most rapid before flowering but continued until maturity (early June) in the winter-sown and until mid to late pod filling (also early June) in the spring-sown crop. Root dry weight (c. 45 g/m2) and length (c. 45 cm/cm2) were similar in both crops during pod filling.In 1983/84, shoot weight, root weight and root length were similar in all genotypes but the later maturity of ILC 3279 resulted in lower seed yield and hence harvest index, and greater water use.The root length density decreased approximately logarithmically with depth in the soil profile although comparison between seasons and with other published results showed that the relations could not be used predictively. Water use efficiency was poorer in the second, drier season and was almost doubled by winter sowing.
71 citations
TL;DR: In this paper, the effects of intake of dry matter, concentration of phosphorus and the physical form of two low-P barley straws upon the faecal losses of P were investigated.
Abstract: Twelve sheep were fed semisynthetic roughage diets at three rates to study the effects of intake of dry matter, concentration of phosphorus and the physical form of two low-P barley straws upon the faecal losses of P. The sheep were in negative P balance throughout the experiement. The absorption of dietary P increased with P intake and was unaffected by differences in the physical form of the roughage. For each barley straw diet, endogenous faecal P increased with dry matter intake, and was higher when the roughage was ground than chopped. Over the whole experiment, daily endogenous faecal P ranged from 8.5 to 31.5 mg/kg live weight. Endogenous faecal P was related to P intake or to dry matter intake and plasma inorganic P. The concentration of faecal endogenous P was negatively related to the intake of each diet. It is concluded that the concentration of inorganic plasma P and the rate of salivary secretion are responsible for the endogenous faecal excretion of P and the regulation of P balance in sheep fed low-P diets.
65 citations
TL;DR: Use of a one-dimensional neighbour method of analysis in 1019 variety trials of a range of crops conducted by plant breeders in four states of Australia in 1985–87 resulted in an average reduction of 42% in variances of varietal yield differences compared with conventional randomized complete block analysis.
Abstract: Use of a one-dimensional neighbour method of analysis in 1019 variety trials of a range of crops conducted by plant breeders in four states of Australia in 1985–87 resulted in an average reduction of 42% in variances of varietal yield differences compared with conventional randomized complete block analysis. Of these trials, 219 were designed as square, rectangular or generalized lattices and the average reduction in variances of varietal yields with incomplete block analysis and recovery of interblock information was 33%. The results emphasized that plots should be wide enough to avoid interplot competition, and that neighbour analysis is of most benefit in trials with short plots or when the field layout has many plots in a row.
TL;DR: It was concluded that a major cause of declining productivity in sown grass pastures is the immobilization of N in decomposing grass litter.
Abstract: The extent and rate of N release from nylon bags containing green panic litter was measured for up to 319 days (long-term studies) in 1978/79 and 1979/80 in Gayndah, Australia. Dry matter (DM) decomposition rates were measured in 41 periods of 39 days and related to environmental variables and initial litter N concentrations (short-term study)
TL;DR: The proportion of the legume in the harvested material was much lower than expected from the seed ratios and Digestibility and crude protein content were highest in the mixtures of triticale and peas.
Abstract: Two small-grained cereals, Mulga oats and a triticale line, and two legumes, local vetch and local peas, were grown in pure stands and in mixtures at various cereal: legume seed ratios (20:80, 40:60, 60:40 and 80:20) for three successive cropping years, 1981/82 to 1983/84, at Laxia and Dromolaxia, Cyprus, in each year.The cereal pure stands produced, on average, more dry matter, 8·40 t/ha, and more digestible organic matter, 4·12 t/ha, than the legume pure stands, 3·68 and 2·18 t/ha, respectively. On average, total dry matter production decreased linearly as the seed proportion of the legume component in the mixture increased. The proportion of the legume in the harvested material was much lower than expected from the seed ratios. The highest proportion of legume was seen in the mixtures of peas with triticale and ranged from 8·1 to 35·5% at the various sowing rates. Digestibility and crude protein content were highest in the mixtures of triticale and peas.
TL;DR: Evaluated the effects of chloride or sulphate salts on the yield and mineral composition of chickpea at different electrical conductivities in arid and semi-arid areas of India.
Abstract: Chickpea is the most important pulse crop of the arid and semi-arid areas. In India, it is cultivated during winter, depending on soil moisture stored from the preceding summer rain, which is often inadequate to ensure a satisfactory crop.In most such areas, saline ground water is the only source of supplementary irrigation to which chickpea, like other pulses, is highly sensitive (Maas & Hoffman 1977). Field observations indicate (Manchanda et al. 1981) that chickpea is more sensitive to chloridedominated than to sulphate-dominated saline water irrigation. Since most saline ground water and saline soils are dominated by chloride or sulphate salts, this study evaluated the effects of these salts on the yield and mineral composition of chickpea at different electrical conductivities. (ECe).
TL;DR: In this experiment moderately high populations of each crop were found to be necessary to obtain beneficial yields from the mixtures and semi-additive mixtures, with 67% of eachcrop's pure stand population, appeared most appropriate.
Abstract: The growth and development of maize and soya bean when grown in mixtures in different proportions and arrangements were studied at Samaru (11° 11' N, 38° E) and Yandev (07° 23' N, 09° 10' E) in the savannah belts of Nigeria. The crops were sown in both pure and mixed stands. The pure-stand densities were 513 plants/m2 for maize and 20·15 plants/m2 for soya bean. Mixtures were made in three proportions: additive (100:100), containing 100% of the sole crop population of each crop; semi-additive (67:67), containing 67% of each crop's sole population; and replacement (67:33 and 33:67), containing 67% of one crop's population to the other's 33%. The mixtures were formed either on the same ridge (in-ridge) or on different ridges (alternate ridge).Maize grain yield at Samuru was not significantly reduced in mixtures except where its proportion was reduced to 33% of its sole crop density. Seed yields in soya bean were significantly reduced in all mixtures, and when associated with maize density of not greater than 67%, soya bean was capable of 50% of its sole crop yield. At Yandev, late planting coupled with inadequate rainfall in the month following planting depressed seed yields in both crops, the sole crop yields being only 1·53 t/ha in maize and 0·24 t/ha in soya bean. Also maize appeared to be adversely affected in the mixtures at this location, the yields being significantly reduced in the mixtures irrespective of planting ratios.All mixtures, except 100:100 at Yandev, proved beneficial by producing land equivalent ratio (LER) values greater than one, while 67:67 proportions made higher gross returns than any of the sole crops at Samaru. In this experiment moderately high populations of each crop were found to be necessary to obtain beneficial yields from the mixtures. In this regard semi-additive mixtures, with 67% of each crop's pure stand population, appeared most appropriate.Incidence of maize streak was significantly lower in alternate ridge mixtures; otherwise the crop in the mixtures seemed to be little affected by pattern of plant arrangement; while soya bean was quite sensitive, its flowering and podding being significantly delayed in in-ridge mixtures at Yandev. The legume yields in this mixture were also slightly, though not significantly, adversely affected. Thus alternate ridge arrangement was more favourable.
TL;DR: Forage oats grown alone showed a very high yield response to N and rainfall ranging from 30 to 18·2 t D.M. yield and had a strong positive effect on total forage crude protein (CP) and mineral composition as mentioned in this paper.
Abstract: Experiments were conducted on the seed rates of the components of oat-vetch mixtures combined with varying rates of nitrogen fertilizer in a rainfed area of north-east Portugal in 1982–3 and 1984–5.Forage oats grown alone showed a very high yield response to N and rainfall ranging from 30 to 18·2 t D.M./ha, but had a very low crude protein concentration (37–54 g/kg D.M.) and a poor mineral nutrient composition.The increased use of vetch in the seed mixture had a buffering effect on dry-matter (D.M.) yield but this depended very much on crop N nutrition. For N-deficient conditions vetch inclusion increased the D.M. yield and had a strong positive effect on total forage crude protein (CP) and mineral composition. When crop N nutrition was good, very high D.M. yields (> 12 t D.M./ha) were possible using a high proportion of oats, with vetch making a reduced contribution to the yield and nutritive value of total forage.Seed rates suggested in the literature for Mediterranean conditions are adequate for low N inputs and low available soil N, but not for high D.M. yields which can only be obtained by using a higher proportion of oats and adequate N fertilizer.
TL;DR: In a field which had been grazed by dairy cows for 26 years, the bulk density of both total soil and fine earth increased rapidly with depth down to 10-12 cm, but decreased below this depth.
Abstract: In a field which had been grazed by dairy cows for 26 years, the bulk density of both total soil and fine earth increased rapidly with depth down to 10–12 cm, but decreased below this depth The bulk density was approximately twice as great in the 10–12 cm as in the 2–4 cm layer Total porosity in the 10–12 cm layer was only 22%Slitting the soil to penetrate the compacted layer approximately doubled net herbage accumulation and the net uptake of N, P and K, raising herbage production and uptake of nutrients from a low level to an acceptable one Slitting tended to increase the concentrations of nitrate-N and K in herbage, but had little effect on the concentration of total N Slitting increased the weight of ash-free root in the 10–20 cm depth range
TL;DR: The ad libitum group grew faster and were larger in all body dimensions on each occasion, except for leg length at 27 months which showed no statistical difference between groups, and the unrationed animals were consistently wider at the shoulders but smaller in leg and chest dimensions.
Abstract: Measurements of skeletal size were made at 2–3-month intervals on 30 Border Leicester × Merino castrate male (wether) sheep between 2 and 27 months of age. Fifteen sheep were fed ad libitum on a high-quality diet and the other 15 half the average amount consumed by the first group, age for age. The ad libitum group grew faster and were larger in all body dimensions on each occasion, except for leg length at 27 months which showed no statistical difference between groups. When the groups were compared over the live-weight range common to both (16–44 kg) the unrationed animals were consistently wider at the shoulders but smaller in leg and chest dimensions.The relationship between each body component and age is described by a Mitscherlich equation and the relationship with live weight by a linear equation in which both variables are log transformed. Separate relationships were determined for each sheep and tested for differences within and between groups.
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TL;DR: Dairy cows offered ad libitum access to grass silage received 8 kg/day concentrate differing only in phosphorus content during the winter feeding period and all animals were grazed together on perennial ryegrass pastures during the summer period.
Abstract: In an experiment, carried out over 3 years, two groups of dairy cows offered ad libitum access to grass silage received 8 kg/day concentrate differing only in phosphorus content (low P concentrate: 4·0–4·5 g/kg dry matter (D.M.); high P concentrate: 6·0–6·5 g/kg D.M.) during the winter feeding period of approximately 6 months. During the summer period all animals were grazed together on perennial ryegrass pastures. There were no consistent significant effects of P content on any of the variables measured. The mean calving indices were 371 (S.E. = 3·71, n = 122) and 379 (S.E. = 4·28, n = 95) days and overall conception rates were 0·70 and 0·68 for the low and high P treatments, respectively. Mean plasma P concentrations during the winter period were significantly reduced (P > 0·01 or greater) in years 2 and 3 of the study on the low P treatment. In 1 year milk yield was significantly higher (P > 0·01) on the low P treatment although the fat content was significantly reduced (P > 0·05) but these effects were not recorded in the other 2 years.
TL;DR: The apparent digestibility of N up to the terminal ileum was significantly higher for wheat than for barley, and significantly higher in high- than in low-protein varieties, while over the whole gastro-intestinal tract, the difference between the cereals was larger; a greater proportion of wheat N than of barley N was digested in the large intestine.
Abstract: Estimates were made of the dry matter (DM) yield and N content of cereal grains harvested from trial plots. They included 236 combinations of variety and treatment, with 13 varieties of winter wheat grown under six husbandry regimes, 14 varieties of spring barley under three husbandry regimes and ten varieties of winter barley under 11 husbandry regimes. The husbandry included timing and rate of fertilizer application, use of growth regulator and fungicide, and seed rate.For all three cereals, there were highly significant positive associations between grain N content (g/kg DM) and grain DM yield (t/ha) when individual varieties were grown under different conditions. The regression coefficients were: winter wheat 2·28, spring barley 0·74 and winter barley 1·06. When varieties were compared under constant husbandry, the association between N content and yield was negative; the regression coefficients were: winter wheat – 1·53, spring barley –1·14 and winter barley –1·21.The contents of lysine, threonine, isoleucine and valine were examined in 19 samples of winter wheat, 19 of spring barley and 21 of winter barley. Each cereal type included a comparison of varieties under one husbandry regime and a comparison of husbandry regimes in one variety.The amino acid composition of wheat protein changed little with either variety or treatment. In spring and winter barley, lysine concentration in grain protein (g/16 g N) decreased with increases in grain N which arose from additional fertilizer N. There were similar decreases in threonine, isoleucine and valine in winter barley, but varietal differences in grain N were not associated with significant changes in the amino acid composition of grain protein.The nutritive values of spring barley, winter barley and winter wheat were compared in digestion and N balance studies in growing pigs. A subset often samples was examined which included, for each cereal type, high- and low-protein varieties, each (except for spring barley) grown with high or low rates of applied fertilizer N.Apparent digestibility of dry matter measured at the terminal ileum was similar (0·67–0·70) in all three types of cereal but there was a tendency for the DM of high-protein varieties to be digested better than that of low-protein varieties. Over the whole digestive tract, the apparent digestibility of the DM of wheat was higher (0·83) than that of barley (0·75).The apparent digestion of the starch of all samples was virtually complete (0·98) by the end of the ileum; the remainder was digested in the large intestine.The apparent digestibility of N up to the terminal ileum was significantly higher for wheat than for barley, and significantly higher in high- than in low-protein varieties. Over the whole gastro-intestinal tract, the difference between the cereals was even larger; a greater proportion of wheat N than of barley N was digested in the large intestine.The rate of N fertilizer application did not significantly affect the apparent digestibility of any amino acid but there were significant differences amongst the cereal types in the apparent digestibility of seven amino acids. The amino acids in high-protein varieties were, on average, 6 % more digestible than those in low-protein varieties.When allowance was made for the endogenous flow of amino acids, some of the differences between cereals and between high- and low-protein varieties disappeared but some significant differences remained.The biological value (BV) of wheat protein (0·43) was significantly lower than that of barley protein (mean 0·57). When pigs were fed wheat as the sole protein source, the higher N content of wheat compensated for its lower BV. There were no significant differences in the rates of N retention between pigs fed on wheat or barley.
TL;DR: Herbage and oil yields of Mentha arvensis, M. piperita and M. spicata increased significantly with N fertilization and those of M. citrata with up to 150 kg N/ha; and oil content decreased in all the species.
Abstract: Herbage and oil yields of Mentha arvensis (Japanese mint), M. piperita (peppermint) and M. spicata (spearmint) increased significantly with N fertilization up to 100 kg N/ha and those of M. citrata (bergamot mint) with up to 150 kg N/ha. Plant height, leaf: stem ratio and leaf area index increased with N application; and oil content decreased in all the species. Economic optimum doses of N for M. arvensis, M. piperita and M. spicata were 167, 153 and 145 kg N/ha, respectively and their oil yields expected from the response equation were 190, 103 and 50 kg/ha, respectively. The calculated optimum fertilizer rate for M. citrata was 225 kg N/ha, giving a yield of 193 kg oil/ha. Oil quality did not vary appreciably with N fertilization.
TL;DR: In a field study of two varieties in Cambridge, UK, in 1985 and 1986, the percentage of total incident radiation intercepted by potato canopies with complete ground cover was as low as 80% for some plots but approached 100% in dense ones as mentioned in this paper.
Abstract: In field studies of two varieties in Cambridge, UK, in 1985 and 1986, the percentage of total incident radiation intercepted by potato canopies with complete ground cover was as low as 80% for some plots but approached 100% in dense canopies. Although percentage ground cover is useful for assessing canopy growth, it is not wholly suitable for estimating light interception and may lead to serious errors in calculation of efficiency of conversion into dry matter.
TL;DR: The data suggested that, when the DE content of the diet falls below 10·5 MJ/kg D.M., the young rabbit is unable to compensate further by increasing daily VFI, and is forced to settle for a low-quality grassmeal diet.
Abstract: Ninety-six young rabbits (48 males, 48 females) each weighing 08 kg were offered one of six diets to appetite (n = 8 per treatment) or at one of four restricted feeding levels (n = 2 per treatment). All animals were culled at ca. 2 kg body weight and carcass analysis was carried out. Nutrient retention was estimated by the comparative slaughter technique.Five of the experimental diets (A–E) were formulated to contain increasing concentrations of a poor-quality grassmeal (0, 100, 300, 500 and 700 g/kg, respectively), the remainder of the diet consisting predominantly of ground oats and soya-bean meal. A sixth diet (F) was based on a common laboratory rabbit diet (SGI). All diets contained similar digestible crude protein (DCP): digestible energy (DE) ratios of ca. 13·1 g DCP/MJ DE. Acid detergent fibre concentrations in diets A–F were 146, 158, 213, 264, 321 and 180 g/kg dry matter (D.M.), respectively.When feeding to appetite, growth rates were depressed at the highest inclusions of grassmeal (diets D and E). Growth rates (GR) and voluntary food intakes (VFI) for diets A–F were: GR (g/day): 40, 41, 43, 36, 30 and 40; VFI (g D.M./day): 93, 103, 120, 137, 159 and 111, respectively. The depression in growth rate on diets D and E was associated with a reduction in total daily DCP and DE intake. The data suggested that, when the DE content of the diet falls below 10·5 MJ/kg D.M., the young rabbit is unable to compensate further by increasing daily VFI. Males grew significantly faster than females (40 cf. 37 g/day) and females had fatter carcasses at slaughter (301 cf. 274 g fat/kg carcass D.M.).Relationships between daily N and energy intake and their retention in the body of the growing rabbit were calculated using data from both restricted and ad libitum-fed animals. Daily energy retention (ER, kJ) was related to daily DE intake (DEI, kJ) by the equation: ER = –227 + 6 x DEI (b ranged from 0·407 to 0·502, according to diet).The estimated maintenance energy requirement of the growing rabbit ranged from 351 to 434 kJDE/kg0·75 per day and the average value across all diets was 377 kJ DE/kg0·75 per day.Daily N retention (NR, g) was related to daily digestible nitrogen intake (DNI, g) by the equation: NR = –0·398 + 6 x DNI (b ranged from 0·589 to 0·667, according to diet).The estimated N requirement for maintenance ranged between 0·464 and 0·525 g DN/kg0·75 per day and the average value across all diets was 0·497 g DN/kg0·75 per day.
TL;DR: It is concluded that yield advantage of F1 hybrids so far tested is not generally sufficient to justify their introduction into U.K. agriculture.
Abstract: In experiments harvested in 1985 and 1986 the grain yields of 61 F1 hybrids among winter wheat varieties and advanced breeding lines were 5·9% greater than the yields of the best parents. In a trial with 430 hybrids in 1986, the hybrids yielded 3·6% more grain than the best parents. Among these 430 hybrids heterosis for yield was greatest for those from the lowest yielding parents. This result is taken to indicate that among these genotypes most genes for high yield have been fixed in the highest yielding parents.The hybrids had slightly fewer ears/m2, but more grains per ear and heavier grains than the highest yielding parents. They yielded more straw as well as more grain.The results are compared with those from other studies and it is concluded that yield advantage of F1 hybrids so far tested is not generally sufficient to justify their introduction into U.K. agriculture.
TL;DR: In this paper, a two-year field experiment on a mollisol at Pantnagar showed that organic sources of N gave generally higher rice yields than the equivalent split dressing of prilled urea (PU), attributed to significant variations in panicles/m 2, filled spikelets/panicle and nitrogen uptake by the crop.
Abstract: A two-year field experiment on a mollisol at Pantnagar showed that organic sources of N gave generally higher rice yields than the equivalent split dressing of prilled urea (PU). In 1985/86, Sesbania green manuring (40 kg N/ha) and PU (40 kg N/ha) and, in 1986/87, Sesbania (40 kg N/ha)+Azolla (40 kg N/ha) gave significantly higher yields than a split application of 80 kg N/ha as PU. Yield increases were attributed to significant variations in panicles/m 2 , filled spikelets/panicle and nitrogen uptake by the crop. These components, and grain yield, were significantly correlated with wet soil NH 4 + -N, which was increased by organic manuring. Wheat grown after each rice crop showed significant residual effects of the different sources of N applied to rice
TL;DR: Breeding for low tannin content in Vicia faba is feasible and selection can be based on plants with yellow-spotted flowers and red testas.
Abstract: Tannin content of the testa was estimated in crosses among six Vicia faba lines of diverse origin using the vanillin-HCl method. Additive genetic variance was predominant in the inheritance of tannin content. Two white-flowered parents possessed different genetic information for tannin content when the pleiotropic effect of genes for white flowers was eliminated. The genes controlling red testa (r), spotted flower (Sdp) and yellow pigment on the flower (yf) negatively influenced tannin content in the testa. Breeding for low tannin content in Vicia faba is feasible and selection can be based on plants with yellow-spotted flowers and red testas.
TL;DR: In this article, a series of 20 two-replicate row-and-column designs for field trials comparing between 25 and 100 varieties on small plots is presented, and the results show that most of the designs perform well.
Abstract: This paper presents a series of 20 two-replicate row-and-column designs for field trials comparing between 25 and 100 varieties on small plots.
ADAS1
TL;DR: The microbial method based on sheep faeces was as effective as that using rumen liquor in digesting ruminant feedstuff's in vitro, and seemed to have a distinct advantage in use.
Abstract: Three in vitro methods, one enzymic and two microbial, were applied satisfactorily to the determination of the dry matter digestibility of forages, but failed when applied to a variety of concentrate feeds. The microbial methods had the advantage that the proportion of weight lost from forages during the in vitro process approximated closely with their determined in vivo digestibilities. The microbial method based on sheep faeces was as effective as that using rumen liquor in digesting ruminant feedstuff's in vitro . Since sheep faeces are readily obtained from intact animals, the faeces liquor method would seem to have a distinct advantage in use.
TL;DR: There was no significant relationship between pod length and seed yield, although the highest- and lowest-yielding lines were, respectively, longand short-podded, and alternative approaches to using pod length as a criterion of selection for high yield are discussed.
Abstract: Ten selections from the cultivar China A, with widely different pod lengths, were compared in a single environment in Perth in 1983. Pod length was correlated positively with seed weight per pod but negatively with number of pods per plant. As a result, there was no significant relationship between pod length and seed yield, although the highest- and lowest-yielding lines were, respectively, longand short-podded.Two lines differing markedly in pod length were compared in a second experiment in 1984 in which sowing date and plant population density within a sowing date were varied. Although pod length was relatively stable, seed yield and some of its components were greatly affected by sowing date and plant density. Again, the long-podded line produced fewer pods with a greater weight of seed per pod than the short-podded line in most conditions. Compensation for greater seed weight per pod by a reduction in number of pods per plant was primarily responsible for the absence of significant differences in yield between lines in any treatment.Although long pods generally produced a greater weight of seeds per pod than short pods, the advantage in seed number and/or the weights of individual seeds was less than that expected pro rata for the much greater pod length. Indeed, short pods produced more seeds per unit length of pod than long pods. This suggested a less efficient distribution of assimilates within the longer pods, a greater amount being required to support the growth of pod walls than in short pods.Alternative approaches to using pod length as a criterion of selection for high yield are discussed.
TL;DR: Characterization of accessions of Lolium perenne collected in Romania, using naturally hardened tillers in an artificial freezing test, is described and cold tolerance of the accessions was positively correlated with the mean temperature of the coldest month at the sites of origin and with persistence in swards after three winters.
Abstract: Characterization of accessions of Lolium perenne collected in Romania, using naturally hardened tillers in an artificial freezing test, is described. Accessions showed contrasting hardening response to variation in the winter environment at Aberystwyth. Cold tolerance of the accessions, measured as lethal temperature for 50% of the tillers (LT50), was positively correlated with the mean temperature of the coldest month at the sites of origin and with persistence in swards after three winters. Superior populations were identified within this collection and are being used as a source of winter hardiness in a breeding programme.The role of temperature and irradiance in the contrasting hardening responses of three accessions was investigated in controlled-environment studies with seedlings.The advantages of environmental simulation techniques for characterization of genetic resources are discussed.