. Annals of applied biology. Biology, Economic; Biochemistry. Winifred E. I^renciilky 151 The association between the amount of growth and the (juantity of soil available is further demonstrated by the efficiency indices of the barley with different rates of seeding (Table VI), the index decreasing steadily with the increase in the number of seeds per pot. Fig. 3 shows this even more strikingly. As the large pots contain exactly twice as much soil as the narrow pots, two seeds in large pots each have as much soil and therefore food available as one seed in the narrow pots, four in large as two
. Annals of applied biology. Biology, Economic; Biochemistry. Winifred E. I^renciilky 151 The association between the amount of growth and the (juantity of soil available is further demonstrated by the efficiency indices of the barley with different rates of seeding (Table VI), the index decreasing steadily with the increase in the number of seeds per pot. Fig. 3 shows this even more strikingly. As the large pots contain exactly twice as much soil as the narrow pots, two seeds in large pots each have as much soil and therefore food available as one seed in the narrow pots, four in large as two in narrow, etc. Consequently in the figure the efficiency in- dices for both sets of pots are plotted together according to the quantity of soil available for individual plants, and the curves are practically co- incident, showing again how entirely dependent the growth is on the available food supply. per 8 seeds per 20 kilos of boil. 4 seeds per 10 kilos of soil. Fig. 3. Black line shows the average efficiency indices for varying numbers of plants grown in 20 kilos of soil (broad pots). Dotted Ime ditto in 10 kilos of soil (tall pots). 2. EFFECT OF INDIVIDUAL FACTORS ON COMPETITION. The above experiments with mustard and barley show that if the food supply in the soil is restricted this will be the chief limiting factor in determining the amount of possible growth, and therefore the action of other factors of competition will be less obvious. On the other hand, these other factors are at work at the same time under these conditions so that the results obtained are not necessarily solely due to competition for food. In order, therefore, to ascertain the w^orking of the various factors it is necessary to arrange experiments in which each may be studied individually, without interference by the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrati
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