ALBERT

Description: XII. SummaryThe experiment was designed to compare under Trinidad conditions three varieties of fodder grass and ascertain the correct stage at which each should be cut to give the maximum nutritive value per acre. It consisted of a yield trial in the form of a Latin square in which the treatment series included four cutting rotations on main plots and three varieties of fodder grass on subplots as appended

Description: The object of this experiment was, in the first place, to see whether, with cotton experiments, there was an advantage in planting a larger number of seeds per hill than the customary number of three; and, in the second place, to see the effect of the interaction of time of thinning with varying numbers of seeds per hill.In cotton breeding work, where trials of new strains have to be carried out as soon as sufficient seed is available, it is important to conserve seed in all possible ways. At the same time it is necessary to plant sufficient seed to give a full and even stand for all strains.In experiments carried out in 1936–7 and 1937–8 stand counts, made soon after germination, showed the advantage of the higher seed rates in obtaining a quick and full stand. Later counts and final counts at harvest showed a considerable evening up, although the two-seed treatment proved unreliable, giving the lowest stand in both seasons.Plant height and weight records, made during both seasons, showed that plants from the larger hills were drawn up much more rapidly than plants from the smaller hills. This rapid elongation in stem height proved, from weight figures, to be at the expense of lateral development, weak and leggy plants being produced in these hills. The ten-seed treatment showed up particularly badly in this respect, the yield figures showing that the plants never recovered from this early deleterious effect.The six-seed treatment, whilst giving a quick and excellent stand suffered to a certain extent from the same defects as the ten-seed treatment. If thinned early they tended to fill out and become more comparable with plants from the three-seed treatment, but when thinning was delayed they never caught up and final yield suffered adversely.

Description: 1. The results of three uniformity trials with a U4 cotton at Barberton are reported. Two of these trials, carried out in a dry year, gave yields in the region of 400 lb. seed cotton per acre; the third, in a wet year, yielded over 1100 lb. per acre.2. Results from the three experiments agreed closely in essential details regarding size and shape of plots.3. In all three cases the percentage standard error per plot decreased rapidly as the plot was lengthened, but tended to increase slightly as the width of the plot was increased.4. The standard error increased as the block size was increased by the addition of more plots, indicating the desirability of keeping the number of strains in a variety trial as low as possible.5. With plots of the same shape the smallest plots were the most efficient, while with plots of the same size the efficiency increased as the plot shape became longer and narrower.6. Two fertility contour maps are given, which illustrate a general patchiness in yield common to cotton crops in the Barberton district.7. Details of the types of plot used at Barberton are given, together with the reasons for their adoption.

Description: The effect of applying a nitrogenous fertiliser to wheat at seven different times and three rates, was studied in pot culture. It was found that the later the time of application the smaller was the increase in the yield of total dry matter and of straw. The increase in the yield of grain, on the other hand, was constant for the first six times of application, the last of which was made on May 25, but a later application made after ear emergence produced no increase.Analysis of the grain yield showed that early application produced its effect by increasing the number of ears per plant. Later applications caused a smaller increase in ear number, but also increased the number of grains per ear and 1000-corn weight. There was no evidence of a critical time for tiller formation such as has been postulated by Doughty and Engledow.The increase in total nitrogen uptake was equal for all times of application, but the ratio of nitrogen in grain to nitrogen in straw and chaff was greater, the later the time of application.The writer wishes to thank Messrs A. M. S. Clarke, G. T. Detlefsen and S. A. W. French for much help with the experimental work, and Mr R. G. Warren for making the nitrogen determinations.

Description: 1. A comparison is made of Δ for the blood of sheep with Δ for the contents of the stomach compartments. It is suggested that the approximate identity of the two sets of values is best explained by the view that absorption takes place from the compartments.2. A variation of 0·570–0·630 is recorded for Δ for the blood of sheep.

Description: 1. The effect of low-temperature treatment on some varieties of wheat, barley and oats has been found to be profoundly affected by the time of sowing of the treated grain.2. Winter sowing showed the least vernalisation effect, while in the spring the stimulative action became more pronounced as far as earing acceleration is concerned, as the sowing was made progressively later. This was particularly marked in winter varieties.3. Developmental studies of the control and vernalised plants showed the stimulative action on early growth and growing point development in the winter varieties.4. Tiller counts on control and vernalised plants of three winter wheat varieties demonstrated the fact that each variety was stimulated to earlier tiller production, but in two of the varieties this resulted in a reduction of surviving ears at harvest.

Description: 1. Following an examination of weaning weight with respect to litter size, it is concluded that no general relation between the two exists. Although a significant regression of weight on litter size was found, it appears probable that in herds where the relation between fertility and milk yield is different, such a regression will not necessarily be found.2. A sampling experiment was carried out to determine the extent to which a sample might be expected to represent the whole litter. A correlation of 0·96 was found between the mean growth rate of samples consisting of the four pigs nearest the average at weaning and the mean of the whole litter. This represents a loss of 8 per cent of the information. With three or two pigs chosen in the same way the loss was greater. Samples of four pigs chosen at random did not give results significantly different from those of the four pigs nearest the average. The choice of the heaviest four pigs resulted in a loss of 15 per cent of the information.3. The slight difference between the results from the random sample and the sample of the four average pigs indicated that there must have been only a small correlation, between weaning weight and subsequent rate of growth. An analysis of post-weaning rate of growth showed that the intra-class correlation of pigs of the same weaning weight was 0·15. Individual weight at weaning would therefore appear to be of slight value in estimating subsequent performance.4. Intra-litter correlations of growth rate for litter classes eight and nine were found to be 0·3 and 0·5. These values are higher than those found by others, probably as a result of the inclusion of the pre-weaning period in the calculation of the growth rates. There would appear to be grounds for believing that at least a fifth of the individual variance may be accounted for by additive gene effects.

Description: 1. The effect of low-temperature grain pre-treatment on two winter varieties of wheat and two winter varieties of barley is seen in a very definite reduction in the number of tillers produced, which, however, had no subsequent effect on the number of ears surviving at harvest. Very little effect resulted from the treatment of spring varieties of wheat and barley in the number of tillers produced, although the spring wheat variety did show a slight reduction.2. Gross yields per plot were unaffected by the treatment in all the varieties, but the yields per plant were affected in the wheat experiment, and the yield per ear in the barley experiment. There was a general increase in the yield per plant of all wheat varieties, while in the yield per ear one barley variety was unaffected, another showed an increase, while the third suffered a reduction.3. The grain from treated plants was affected in 1000-grain weight and nitrogen content in the wheat experiment, while only the 1000-grain weight suffered any change in the barley experiment. Only one wheat variety showed an increase in 1000-grain weight, while each of the three varieties responded differently with regard to the nitrogen content of the grain. Similarly, each of the three barley varieties was affected differently with regard to 1000-grain weight, one being unaffected, another showing a decrease, while the third showed an increase.4. Analysis of the behaviour of the varieties with regard to tillering and ear production showed clearly that the maximum of tillers produced bears little relation to the number of ears at harvest. In the barley varieties high yield and low nitrogen were associated with the largest number of ears, which in turn was associated with the lowest tillering. In the wheat varieties high yield was associated with high 1000-grain weight. In both experiments the spring varieties outyielded the winter varieties whether the latter had been treated or not.

Description: 1. It is shown that the leaf area: leaf weight ratio decreases with increasing leaf weight.2. The relation between the leaf area: leaf weight ratio and leaf weight is well fitted by a linear regression equation.3. A method of estimating the mean leaf area per leaf or per plant of a field crop by means of this regression is described. The mean weight per leaf is determined by a large sampling, and the leaf area: leaf weight ratio and its regression on leaf weight are estimated on a small subsidiary sample.4. Alternative methods of estimation from the mean leaf weight and either the unweighted or the weighted mean leaf area: leaf weight ratio are shown to give positively biased estimates of mean leaf area.5. It is emphasized that the small sample, from which the leaf area: leaf weight ratio and its regression on leaf weight are determined, must be a strictly random selection from the whole population.