SUMMARYSeeds of Phaseolus vulgaris L, cv, Nerina were hand-sown inside open-top chambers (OTCs) in which the plants were exposed to charcoal-filtered air (CF treatment), ambient air (NF), or ambient air with added 6, 12, 18, 25 or 30 nl r^ of ozone (NF6, NF12, NF18, NF25 and NF30 treatments, respectively). Exposure commenced as the crop emerged and continued on a daily basis until the end of the season. Ozone (O3) was added between 10,00 and 18,00 h GMT, The seasonal 7 h mean O3 concentrations ranged from 10 nl I"^ in the CF treatment to 50 nl r ' in the NF30 treatment.The growth and yield of P. vulgaris cv, Nerina demonstrated two distinct responses to O3 depending upon concentration. At seasonal 7 h means of 20, 26 and 32 nl 1"' (NF, NF6 and NFI 2 treatments respectively), the yield increased relative to that of the CF" treatment. The increase in yield peaked at 48% in the NF6 treatment {P < 0-05), and was associated with a 55 % increase in the maximum leaf number, longer retention of the canopy, and a 45 % increase in the number of pods present at the Rnal harvest. In contrast, seasonal 7 h mean O3 concentrations of 38, 45 and 50 nl T' (NFI8, NF25 and NF30 treatments) caused 26^2 "o reductions in the yield of P, vulgaris. The leaves of such plants developed extensive symptoms of O3 injury and were prematurely abscised from the plants. The reductions in yield were due to a decrease in the numbers of seeds per pod and in the weights of individual seeds.

Economic losses caused by weed competition in Manitoba grain crops were studied on 142 farm fields during a 3-year period, 1956 to 1958 inclusive. Ten paired plots were located in each farm field, one-half of each paired plot being kept weed-free throughout the growing season. Per cent protein was determined on wheat, barley and oat samples collected from 60 of these farm fields. Significant increases in protein content were obtained following weed removal in 22 of the 60 grain fields studied and small increases were noted in most other fields. In the combined analysis of all fields, removal of weeds resulted in significant increases (P =.01) in both protein content and yield of wheat, barley and oats. This suggests that weeds compete very effectively with grain crops for available nitrogen and that reductions in crop yields resulting from weed competition are generally accompanied by reductions in protein content as well.

The averages and ranges for thiamine in approximately 250 samples of cereals tested, expressed as μgm. per gm., were: barley 4.2 (3.3–5.7), oats 6.7 (3.8–8.6), wheat 4.5 (3.4–5.9); for riboflavin: barley 1.3 (0.9–1.6), oats 1.3 (1.0–1.7), wheat 1.2 (1.0–1.4). There was a marked increase in the thiamine content of oats over that for 1946—amounting to 0.7 μgm. per gm. Barley and wheat showed slight increases. The values for riboflavin in the three cereals grown in 1947 were about the same as those for the 1946 samples. Varietal effects on thiamine content differed somewhat from those observed in 1946. For barley, Garton, OAC21, Sanalta, and Montcalm were about equal and slightly better than Plush. The order of thiamine content of wheat—for those varieties of which more than 10 samples were tested—was Carlton, Regent, Redman, Thatcher, and agreed with the findings for the previous year. Durum wheats showed higher thiamine levels than spring wheats. There was no varietal effect on the thiamine content of oats. There was no varietal effect on riboflavin content of any of the cereals. None was observed for the 1946 samples. For 1946 no soil zone effect on vitamin content of any of the cereals was noted. In 1947 rendzina and black earth soils produced wheats with higher thiamine contents. An environmental effect other than that for soil zone on the thiamine and riboflavin content of wheat and oats was confirmed.

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A review of the literature on the ascorbic acid content of cabbage reveals such wide variations that it is difficult to state with any degree of confidence what figure or even what range of figures should be used to indicate the vitamin C value. I n this paper we hope to show a method for obtaining data that can be treated statistically to obtain a mean that is the best representation of the ascorbic acid value of cabbage.I n a compilation of vitamin values by Booher, Hortzler, and Hewston (1942) the lowest figure for the vitamin C coiitent of raw white cabbage is 14.3 mg. per 100 gm. and the highest figure is 180.9 mg. per 100 gm. This great variability is due to many factors among which variety and season are undoubtedly important. These two factors were stressed particularly by the following investigators : Gould, Tressler, and King (1936), working with six varieties, three summer and three winter, state that summer cabbage has more vitamin C than winter cabbage. Burrell, Brown, and Ebright (1940), using 30 varieties and strains, report a range from 48 to 180.9 mg. per 100 gm. with the higher values for summer cabbage. Lampitt, Baker, and Parkinson (1945) analyzed cabbages at various times throughout the year. I n all they had 334 analyses with an average vitamin C content of 0.6 mg. per gm. for most of the year but with higher values f o r spring and early summer.Not only is there a difference in the vitamin C value of cabbages owing to variety and season but the distribution of the vitamin is not uniform within the cabbage itself, as shown by the results of the following investigation : Sheets, Leonard, and Geiger (1941) reported that the outer green leaf blades of cabbage contained more vitamin C than the inner, bleached ones. aallott (1942) also reported that the outer leaves of Milan cabbage, with a range from 130 to 140 mg. per cent, contained more vitamin C than did the iiiiier leaves. On the other hand, Ranganathaii (1935) obtained more for fresh inner leaves than for outer leaves with values of 132.6 and 125.8 mg. per cent, respectively. Last year in a preliminary investigation in our own laboratory it was found that the ascorbic acid concentration was highest in the core, being 88.1 mg. per cent. The content of the outer tissue was 48.5 mg. per cent, while the inner tissue was slightly higher at 52.2 mg. per cent. Further analysis this year showed that the outer quarter of local cabbage contained 31.3 mg. per cent, while the inner quarter, not including the core, contained 42.4 mg. per cent. Although these data do not agree as to the part of the cabbage which 236