The relative boron tolerance of three varieties of tall wheatgrass [Agropyron elongatum (Host) Beauv.], ‘Alkar,’ ‘Largo,’ and ‘Nebraska P. I. 98526,’ grown in nutrient cultures was determined. Alkar was also tested in soil cultures. Boron concentrations responsible for a 50% decrement in growth in nutrient cultures ranged from 33 to 38 ppm water-soluble B for the three varieties. The B level causing a 50% decrement in growth of the Alkar variety in the soil culture was 46 ppm water-soluble B in the soil solution.

Cotton varieties adapted to various regions of the Cotton Belt of the United States showed differential leaf crinkling symptoms and growth in greenhouse pots of acid Manteo soil (pH 4.5) from Orange, Va, Subsequent experiments with soils and nutrient solutions containing variable Mn confirmed the hypothesis that the plant symptoms were due to Mn toxicity; however, other evidence indicated that Al toxicity was more important than Mn toxicity in limiting growth. Cotton varieties showing the greatest tolerance to excess Mn in soils or nutrient solutions were ‘Rex Smooth Leaf’ (Arkansas), ‘Acala 1517D’ (New Mexico), and ‘Gregg’ (Texas). Varieties showing the least tolerance were ‘Acala 4-42’ (California) and ‘Coker 100A’ (South Carolina). Tolerance of some varieties was attributed to the fact that they or their ancestors were developed on high-Mn soils. Greater Mn tolerance of the Rex Smooth Leaf variety appears to be due not to reduced Mn uptake but to a greater ability to tolerate a high level of Mn in its tops. Cotton varieties having greatest tolerance to Mn were not necessarily those showing greatest tolerance to Al in a previous study.

Seedlings of four Agrostis species, two represented by two varieties each, were grown with continuous light and supplied with a complete nutrient solution. Within 5 weeks significant differences developed among species in several characteristics. A. alba L. plants had large leaves and stems, whereas those of A. canina L. were small in leaf size and stem diameter. A. palustris Huds. and A. tenuis Sibth. were intermediate in leaf size and stem diameter, but differed from each other in stem length and growth habit. A. alba and A. tenuis were upright in growth habit, but most plants of A. canina and A. palustris were decumbent. Plants could be classified easily as to species. Significant differences were not found between the varieties of A. palustris, ‘Penncross’ and ‘Seaside,’ but varieties of A. tenuis, ‘Exeter’ and ‘Highland,’ differed in several characteristics.

Plant analyses can be a powerful tool in the diagnosis of yield depressions. Critical plant composition data for corn, soybeans, wheat, and alfalfa are presented which can be useful in interpreting plant analyses. Data are also presented to indicate “normal” variations that may be expected to occur in plant composition resulting from variations hi varieties, seasons and soil. For the corn plant, the nutrient composition of some elements change with the leaf sampled and the maturity of the plant.

In Zea mays L., Sorghum vulgare Pers., and Setaria italica (L.) Beauv,, leaf number, an attribute differing with genolype and modified by temperature and photoperiod, is correlated with plant weight and height, photosynthetic area, time of flowering, and length of life cycle. Eighteen lnaize hybrids representing a wide range of genotypes, two maize races, three sgrghum varieties, and Hungarian millet were grown variously in CERES, the Canberra phytotron, under intense sunlight radiation and a variety of daylength and emperature regimes. In maize, the average change in leaf number per egree increased from 0.17 to 0.33 over the day/night temperature range 15/10, 21/16, 30/25, and 36/31 C under 16-hour daylengths, with about the same average increase under 10.hour days. Under short days, at 30 and 21 C, leaf numbers were reduced 2.6 and 1.8 below long-day values. With 30 C day temperature and 16-hour daylength, the earliest hybrid developed 15 leaves, the latest 22.3. Leaf numbers per plant were greatest at the higher temperatures, least at the lower, the average difference being almost six leaves per plant. For plants grown at high temperatures, cold treatments up to emergence of the 7th leaf decreased leaf number only in the earlier hybrids. Changes in nutrient level did not alter leaf numbers in the one hybrid studied. Within temperature regimes, leaf number was correlated with dry weight, leaf area, and height per plant at tasseling and with days to tassel emergence. Leaf numbers in sorghum and Hungarian millet responded to environmental changes in abaut the sanle manner as in maize.