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The pulsed NMR technique for rapid and nondestructive determination of oil in oilseeds has been developed. The effects of spin-lattice relaxation time, spin-spin relaxation time, seed moisture, angular position of the seeds, sample tube thickness, and sample height upon the magnitude and reproducibility of the NMR signal were studied. Based upon these studies, various parameters for seed oil analysis have been fixed. The oil content of Brassica, peanut, and sunflower seeds was determined. The reproducibility of the measurement is ± 1 %. The technique was tested by measuring the oil content of the same seeds by the cold percolation method (CCl4 extraction). It was further tested by determining the oil content of 60 Brassica seed samples independently at three laboratories. The results of these tests are given.

The possibility that symptoms of flooding damage in plants are primarily caused by an accumulation of ethylene was investigated using pot-grown sunflower (Helianthus annuus) plants. When plants were flooded to the basal pairs of leaves, ethylene in roots and stems below the water line began to increase. This coincided with the start of hypocotyl hypertrophy and new root formation in hypocotyls, which continued for 14-16 days. There were highly significant correlations between ethylene concentration and number of roots and hypocotyl diameter. After approximately 4 days of flooding, ethylene concentrations in stems between nodes for the 1st and 3rd basal pairs of leaves started to increase, coinciding with initiation of chlorophyll breakdown and epinasty of the 2nd basal pairs of leaves. Thus, there were correlations between ethylene concentration and chlorophyll breakdown and epinasty. The lower the leaves, the more chlorophyll breakdown among 1st, 2nd, 3rd, and 4th basal pairs of leaves. The longer the flooding, the more severe the flooding damage; and even when returned to normal condition, plants flooded longer than 3 days were not able to recover from flooding damage. A gas chromatographic study revealed that Ethephon was absorbed by roots and decomposed to ethylene in the plant. Damage symptoms caused by soil application of Ethephon, such as reduced stem height, chlorophyll breakdown, epinasty of the 2nd basal pairs of leaves, and hypocotyl hypertrophy, were almost identical with those caused by soil flooding treatment. Microscopic studies revealed that radially enlarged cells and increased intercellular spaces in the cortex were the major contribution to the increased hypocotyl diameter in both flooded and Ethephon-treated plants. It is concluded that the increase in ethylene concentration in flooded plants is largely, although not exclusively, responsible for flooding damage symptoms.

SUMMARYAvailability of soil water was investigated and the methods of determining the lower limit of availability by biotic and standard 15-bar pressure were compared. Greenhouse-grown sunflower and okra were the test crops for the biotic method. The pressure membrane equipment was used for standard 15-bar moisture determination. Okra and sunflower took up water beyond the standard 15-bar tension, thus lowering the moisture content at moderate wilting below the generally accepted values. In topsoil okra wilted at very high tensions, but at somewhat lower tensions in subsoil samples, unlike sunflower which wilted at higher tensions in subsoil samples. An equation is given which may be used to estimate the moisture content at the moderate wilting point of plants with known wilting tensions.

Activity of nitrate reductase in roots and cotyledons of cotton seedings (Gossypium hirsutum L. cv. Deltapine 16) increased rapidly on germination, reaching a maximum after 1 day of imbibition. Thereafter, activity declined until emergence and greening of the cotyledons, when it again began to increase steadily. Germinating soybean (Glycine max (L.) Merrill cv. Merit) and sunflower (Helianthus annuus L. cv. Peredovic) seedlings did not show the early peak of activity. The early peak depended on nitrate and was sensitive to cycloheximide, but not to actinomycin D or other inhibitors of RNA synthesis. The second, light-dependent increase was sensitive to actinomycin D. In roots, the early peak of activity occurred before any growth. After emergence of the root tip from the seed coat, activity was localized in the terminal 2 millimeters, whether expressed on a fresh weight, protein, or root basis. The difference in activity between the apical (0-2 millimeter) and subapical (2-4 millimeter) segments did not result from differences in nitrate availability, energy supply, or turnover rates of nitrate reductase. Root activity was similar to that of the cotyledons after emergence, in that both were sensitive to actinomycin D.

The potential growth-regulating compound 4-chloroglutaranilic acid (CGA) was tested in whole-plant bioassay systems which utilized sunflower seedlings (Helianthus annuus, L.). Test systems included the growth of plants in soil , solid inert (Vermiculite) substrate, and hydroponic (Seed-Pak) pouches.

Summary The response of the light-stimulated rise in glycolate oxidase activity to treatment with actinomycin D and cycloheximide was investigated in developing sunflower cotyledons. The increase in enzyme activity normally starts at the third day of germination and continues for 2–4 days. It was inhibited by actinomycin D only if the antibiotic was added before the third day. Actinomycin D treatment of cotyledons from 2-day-old dark-grown seedlings was without effect on the rise in glycolate oxidase activity. This negative response was due neither to a photo-destruction of the inhibitor nor to a failure of the antibiotic to be absorbed. The absorption could be demonstrated by morphological effects caused by actinomycin D at this stage of development. When actinomycin D was applied to dark-grown white mustard seedlings shortly before placing the seedlings in the light, actinomycin D again did not inhibit the rise in glycolate oxidase activity in the cotyledons. But the light-mediated synthesis of anthocyanin was strongly suppressed by the antibiotic. — Cycloheximide inhibited the increase in glycolate oxidase activity whenever it was added to sunflower cotyledons during their development. — The results are discussed in view of the regulation of microbody function in sunflower cotyledons.

The processing conditions for obtaining high oil quality and yield in continuous caustic refining of the following crude oils are given: tallow, palm, fish, rapeseed, and sunflower. pH Monitoring of reaction mixture assures proper caustic dosage. pH Set point range for various crudes is noted.

Uptake, translocation and complex formation of 14C-labelled 4-amino-3,5,6-trichloropicolinic acid (picloram) and 2,4-dichlorophenoxyacetic acid (2,4-D) in seedlings of rape (Brassica napus L. cv. Nilla) and sunflower (Helianthus annuus L. var. uniflorus) were studied. Sunflower is susceptible both to 2,4-D and picloram, while rape is susceptible to 2,4-D but more tolerant to picloram. The uptake of the herbicides through the leaves was almost complete in both species. Translocation of 2,4-D into the roots took place more readily than that of picloram. In sunflower about 50 per cent of the applied 2,4-D was extruded through the roots into the nutrient solution after 9 days. In the picloram-treated sunflower most of the activity was found in the aerial parts, while in picloram-treated rape most of the activity still occurred in the treated leaf after 9 days. No activity at all was found in the roots or in the nutrient solution of the picloram-treated rape seedlings. While the major part of 2,4-D always was found in the state of free herbicide, a large fraction of picloram was rapidly bound into water-soluble complexes. This binding was especially pronounced in rape. Separation by paper chromatography showed that different radioactive compounds were formed. Most of these could be hydrolyzed, thereby releasing free herbicide. The results support the hypotheses that complex formation could counteract herbicide translocation and toxicity of auxin herbicides.

Relatively low concentrations of Pb, Cd, Ni, and Tl inhibit photosynthesis and transpiration of detached sunflower leaves ( Helianthus annuus L.). The primary mode of action is the interference with stomatal function. Photosynthesis is reduced by 50% of maximum when left tissue concentrations in mM · g −1 are 0·31 (63 ppm) Tl, 0·85 (96 ppm) Cd, 0·93 (193 ppm) Pb, or 1·35 (79 ppm) Ni.

A normally grown crop of sunflower on red sandy loam soils was found to remove considerable quantities of chloride and sodium. On heavy clay soils with saline patches sunflower plants removed large quantities of sodium followed by chloride and sulphate. In view of its salt tolerance, it is suggested that intercropping or rotation with sunflower might help reduce soil salinity and improve soil conditions where salinity problems are coming up especially in heavy clay soils with low permeability. re]19720711

Sunflower (Helianthus annuus L. var. Giganteus) and corn plants (Zea mays L. var. Velox) were grownin mono and mixed culture for 11 days in nutrient solution containing no iron, inorganic Fe3+ and FeEDTA (2 ppm Fe each) respectively to evaluate the interaction between both plant species on their ability for iron uptake. Both plant species developed chlorosis under iron stress (no iron, inorganic Fe3+); however, due to the ability of sunflower plants to lower the pH of the nutrient solution under iron stress conditions, in presence of inorganic Fe3+ the pH lowering was followed by regreening of sunflower in mono and mixed culture. In mixed culture but not in mono culture corn plants also regreened under these conditions. With respect to iron accumulation, therefore, the sunflower plants promoted the uptake and translocation of iron to the shoot of corn plants, i.e. an ‘Fe-efficient’ species can improve the iron nutrition of an ‘Fe-inefficient’ one. In contrast to this corn plants had little or no effect on the iron nutrition of sunflower plants. The corn variety used in this experiment developed chlorosis even in presence of 2 ppm Fe in form of EDTA. This high susceptibility to iron chlorosis was related to the P/Fe ratio in the shoot rather than to the capacity of the plants for absorption and translocation of iron, because sunflower plants with the same or even lower iron content but lower phosphorus content were green.

The Peltier-cooled thermocouple dewpoint hygrometer technique of in situ measurement of leaf water potential was further developed. The observed response of the instrument agreed so well with theoretical analysis that calibration based on theory was within 1% of that obtained using salt solutions of known water potential. Simultaneous measurements with the hygrometer and a beta gauge were made to derive the leaf water content–potential relationships for several crop plants. Results showed relative water contents dropping only to near 0.95 for mature corn (Zea mays L.); sorghum (Sorghum vulgare Pers.); and sunflower (Helianthus annus L.) leaves, and to 0.90 for not quite mature soybean (Glycine max (L.) Merr.) leaves as potentials declined from near −1 bar to the plant wilting point (−8 to −14 bars). Further decline of leaf water potential resulted in relatively much greater loss of leaf water.

(14)C-(UL)-l-Alanine was applied to the surface of mature leaves at the second node of sunflower (Helianthus annuus L. cv Commander) plants, under illumination. The alanine was absorbed during a 4-hour period, and some of it was metabolized by the absorbing tissue. After a lag period of about 15 minutes from first application, distribution of (14)C through the plant proceeded in much the same pattern as when (14)CO(2) is assimilated by similar leaves. Most, if not all, of the (14)C exported from the absorbing regions was in sucrose. Only minute amounts appeared in alanine or other amino acids in surrounding parts of the leaf blade or in the petiole, although these were strongly labeled in the tissue absorbing (14)C-alanine.When (14)CO(2) was supplied for 15 minutes to leaves of different ages, amino acids were lightly labeled in the leaf blade. Mature green leaves exported only sucrose. Yellowing leaves on 60-day-old plants exported a variety of substances including amino acids.

Octopine has been detected in normal tobacco leaf and stem tissue, normal sunflower stem tissue, pinto bean leaves, and normal tobacco callus tissue in culture. Octopine was identified in extracts by means of electrophoresis and chromatography in several solvent systems. Tobacco and sunflower tumor lines induced by various strains of Agrobacterium tumefaciens were found to contain from 1 to 240 times as much octopine as the normal plant tissues examined. Several strains of A. tumefaciens produce undifferentiated tobacco tumors containing high levels of octopine, but produce undifferentiated sunflower tumors containing normal levels of octopine and high levels of arginine. Further, strain CGIC of A. tumefaciens produces in tobacco an undifferentiated tumor which contains high levels of octopine and a teratoma which contains normal levels of octopine. This evidence shows that there is no consistent relationship between the causative strain of A. tumefaciens and the octopine content of the resulting crown gall tumor.

Stem elongation of sunflower plants inoculated at the two-leaf stage through apical buds with Plasmopara halstedii was greatly inhibited. Systemically infected plants did not show normal phototropic and negative-geotropic responses. There was a positive correlation between stunting of infected plants and ability of stem slices to remove indoleacetic acid (IAA) from test solutions. IAA disappearance in the presence of stem slices of infected plants was also highly correlated with area of mildew symptoms on leaves. Although IAA disappeared in the presence of all diseased tissues, leaf tissues were least active. No IAA disappeared in the presence of sporangia of the pathogen. These results explain reduced levels of IAA observed in mildew-infected sunflowers in earlier studies and may account for the characteristic stunting of systemically infected plants.

The efficiency with which plants transport water is related to the water potential differences required to drive water fluxes from the soil to the leaf. A comparative study of two woody and three herbaceous species (Citrus sinensis L. cv. Koethen, Pyrus kawakami L., Helianthus annuus L. cv. Mammoth Russian, Capsicum frutescens L. cv. Yolo Wonder, and Sesamum indicum L. cv. Glauca) indicated contrasts in water transport efficiency. Depression of leaf water potential in response to transpiration increases was found in the woody species; the herbaceous species, however, had more efficient water transport systems and presented no measurable response of leaf water potential to transpiration changes. Different maximum transpiration rates under the same climatic conditions were observed with different species and may be accounted for by stomatal response to humidity gradients between leaf and air. Leaf diffusion resistance in sesame increased markedly as the humidity gradient was increased, while leaf resistance of sunflower responded less to humidity. Stomata appeared to respond directly to the humidity gradient because changes in leaf water potential were not detected when leaf resistance increased or decreased.

SUMMARYGrowth of the sunflower cultivar Peredovic was examined when exposed to periodic severe moisture stress, with and without soil drench application of CCG at the two-leaf stage. The experiment was conducted in sand culture under partly controlled environment conditions. Morphological and physiological measurements were made throughout the growing period. Amongst the responses to CCC were increased stem and petiole width, and decreased length of internodes, head diameter and photosynthetic area. Moisture stress reduced photosynthetic area and the root/shoot ratio. Both CCC and moisture stress increased the number of stomata per unit area.

This report contains an analysis of the carbonized seed remains from the Mitchell Site (39DV2), an Over Focus village near Mitchell, South Dakota. The motive for the study is to explore the amount and kinds of nutritional and material resources which the botanical world (of seeds) provided these villagers. Eight proposi tions and goals are outlined to be tested by the analysis. The use of flotation and sieving through #40 (.0165 in.) mesh screen of all materials was found to be the most efficient method for recovering seed remains. Forty-five genera and species of prehistorically-deposited (carbon ized) seeds are identified. Corn appears in nearly all samples, suggesting that this crop, along with bison meat, provided a major source of food. Quantities of the weed seeds Chenopodium sp. and Amaranthus sp. are clearly associated with corn and seeds of the domesti cated sunflower. Tobacco seeds are also identified for the second time on the Plains. A table of associations and specific Chi-square tests are used to interpret the relative significance of the seeds identified here. In addition, ethnographic data on the use of particular seed types is included where no archaeological use can be inferred.

Summary Watercultureexperiments with different plants fed with cyanamide as nitrogen source led to the following results: Cyanamide doses between 50–100 mg N per 1 nutrient solution rised definitely the content of free arginine in leaves, stems and roots of rape, corn, sunflower, wheat and white cabbage in comparison with other forms of nitrogen, such as nitrate-, ammonium-, and amidino-nitrogen. The activity of arginase is inhibited by cyanamide. The increase of the arginine content is explained as a possible direct synthesis of arginine from cyanamide via guanidino compounds as well as a reduced enzymatic breakdown of arginine. Cyanamide in not critical doses will be rapidly metabolized in plants.

Broad bean 5.8-S rRNA was digested separately with T1 and pancreatic A ribonucleases and the resulting oligonucleotides (27 and 19, respectively) were fractionated by two-dimensional electrophoresis. The oligonucleotides were further analysed and the nucleotide sequences of most of them determined. They were compared with those from 5.8-S rRNA of dwarf bean, tomato, sunflower and rye. The results suggest that the sequence of the molecule has been highly conserved during the evolution of the flowering plants.

Detached corn and sunflower leaves exposed to various concentrations of Cd, supplied as CdCl2, exhibit reduced photosynthesis and transpiration. The reduction is dependent on the concentration of CdCl2 solution and generally becomes more pronounced with time. In sunflower, net photosynthesis and transpiration are completely inhibited within 45 min after the introduction of 18 mM Cd. Within two hours net photosynthesis is reduced to 40% and 70% of maximum after the introduction of 9 and 4.5 mM Cd respectively. In corn the trend of photo-synthetic response to Cd is similar to that in sunflower except that the inhibition in corn is more pronounced at all treatment levels. A strong linear relationship between photosynthesis and transpiration inhibition is obtained in both species suggesting that Cd contamination induces stomatal closure.

Peltier-cooled thermocouple dewpoint hygrometers were used to measure leaf water potentials at several transpiration rates on intact corn (Zea mays L.), soybean (Glycine max (L.) Merr.), and sunflower (Helianthus annus L.), grown in a controlled environment in silica sand rooting media frequently watered with nutrient solution. Hygrometers were left in position for the duration of measurements on each plant, but tests showed this to have little effect on measured potentials. Measured potentials were found to be linearly related to the transpiration rates (correlation coefficients greater than 0.98). Extrapolated values of leaf water potential at zero transpiration were within a few tenths bar of measured nutrient-solution potentials. These results indicated that plant resistances to water flow remained constant from near zero transpiration up to the maximum obtained average rates of 1.8–3.0 g dm−2 h−1. The magnitude of the resistance varied considerably from plant to plant even within a single cultivar of one species and definite conclusions as to interspecies differences in resistance were not made. Estimates of the relative resistance in the root, stalk, and the leaf that were made for a few plants were similar to previously published results.

The life and seasonal histories of Gymnocarena diffusa Snow (Diptera: Tephritidae) were studied during 1971 and 1972 under both laboratory and field conditions. Host range for G. diffusa are species of Helianthus , principally H. annuus L. and H. maximiliani Schrad. G. diffusa is univoltine with an apparent obligatory diapause in the overwintering pupae. Adult flies emerged in mid-June; a sex ratio of 60% male, 40% female was recorded. Males reached sexual maturity 5 days after emergence; this maturity was correlated with development of the ejaculatory apodeme. Preoviposition period for females averaged 17 days; oviposition occurred in commercial fields by mid-July when buds were 2–8 in diameter. Eggs were laid singly on the involucral bract. Larvae fed in the receptacle for an average of 30.6 days. Infestations of sunflower varieties by G. diffusa averaged 56% with up to 7 larvae recorded per sunflower head.

For single unstressed plants, the distribution of leaf area as a function of azimuth angle shows a trend towards a preferred azimuth which can be supported statistically. Young sunflower leaves, and to a limited extent bean leaves, follow the sun and the preferred azimuth therefore changes from east to west during the day. With pepper and cucumber a significant trend towards a northeasterly azimuth was found irrespective of the sun's position. Distributions are given in terms of the cosine of the angle between the sun's beam and normals to the surfaces of the leaves, and the phase angle between the leaf-normal projection on the solar plane and the sun's beam. Calculations show that the heliotropism of sunflower leaves and to some extent of bean leaves, significantly increases the radiation intercepted by these species throughout the day compared with that expected for a random leaf distribution.

An adaptation of Van den Honert's model of the soil—plant—atmosphere continuum is useful for understanding how leaf water potential is influenced by soil and atmospheric factors in the complex natural environment. In field-grown citrus, climatic and leaf resistance changes causing increased transpiration rates resulted in reduced leaf water potentials; however, the relationship between leaf water potential and transpiration was influenced by soil water potential and soil temperature, as predicted by the model adaptation. Leaf water potentials of young greenhouse-grown sunflower and sesame plants remained constant and high over a broad range of transpiration rates, suggesting a much more efficient water transport system for these plants. The comparison of the relationship between plant water balance and transpirational flux for contrasting species and environments is a promising approach for understanding the suitability of crop plants for their environment.

In order to clarify the morphological and physiological causality responsible for the sterility in sunflower, the authors carried out histological observations on the male sterile plants as comparing with fertile ones. Fertile and male sterile inflorescences of sunflower (Helianthus annuus L.) 'P 21 ms' which inherit male sterility genetically, were used for this study. For histological observations, paraffin sections were cut to a thickness 15 μm and stained with the modifications of triple stain of Himes'es et al.. On observation with the behavior of tapetum during microsporogenesis, the sunflower studied in this experiment belong to the plasmodial type. After the microspore stage, distinguishable differences in the anther were observed. The tapetal cell wall of the fertile anther breaks down, and the tapetal protoplasm extruds into the anther loculus to envelop the microspores. On the contrary, tapetal cell wall of the sterile anther exists in situ and the tapetal cell increase in size. In addition, at both sites and shapes of tapetal nuclei at the microspore stage, a clear difference between the two types of fertilities could be distinguishable. As a result it is concluded that the abnormality of the tapetal cell lysis is closely related with male sterility. And it is also presumed that the sites or shapes of the nuclei were related with male sterilty. For the histochemical reactions, no conspicuous difference between the types of fertilities could be observed.

SUMMARYNine high-oil varieties of sunflower were evaluated for their reactions to salinity during emergence in salinized soil culture ranging from 0 to 12·80 mmhos/cm under controlled temperature of 27±1 °C. The varieties were Louck, Vniimk-8931, Chernianka-66, Record, Armarisky, Peredovik, Orizont, Mhjak and Zarea.Soil salinity decreased the percentage of emergence in all varieties of sunflower. The rate of decrease in emergence of some varieties was greater than others. Among varieties tested Vniimk-8931 (a tall variety) and Chernianka-66 (a dwarf variety) showed the highest and the lowest tolerance to salinity at 7·60 mmhos/cm, respectively. For electric conductivities above 7·60 mmhos/cm, the nine varieties of sunflower could be classified in three categories. Vniimk-8931, Record, Louck, Peredovik and Armarisky as high salt tolerant, Mhjak and Orizont as medium salt tolerant and Chernianka-66 as low salt tolerant varieties.

The construction and use of several sizes of cages for experiments or colony rearing of the large milkweed bug, Oncopeltus fasciatus (Dallas), are described. Large adults are produced by a mean sunflower seed consumption of about 60 mg per bug, of which 1/3 is retained as dry body weight, and smaller adults by limiting consumption to about 30 mg per bug. Water consumption is of the order of 20% of live body weight per day at 30°C. Adults can be stored at 14°C for 3 months without food and for at least 5 months with an aqueous (SYE) solution of 50% (w/w) sucrose and 1.25% yeast extract, absorbed in polyester fleece. Survivors, restored to 30 °C with seed, produce enough viable eggs to maintain the colony; egg production is larger if the cold-storage period is shorter, but still lower than that of unstored colonies. First-stage nymphs can be stored for 2 months at 14°C on SYE; mortality is high but survivors grow and reproduce at 30°C on seed. Larger nymphs, like eggs, do not tolerate prolonged cold-storage. During 14°C storage there is little or no seed-feeding, mating, or egg production, but nymphs can still molt at least once. The sucrose intake rate is ca. 20—30 mg/g-day at 30°C but only % as great at 14°C. The rearing system described minimizes labor and various potential problems; frequent servicing is required only during the egg-production stage.

1. Symptoms of sulfur deficiency developed quickly in tomato plants. They were: chlorosis of leaves, the upper leaves becoming yellow first, anthocyanin development in leaves and stems, small leaves with stiff texture, and thin stems. 2. Minus-sulfur stems were high in starch, sucrose, total soluble nitrogen, and the soluble nitrogen fractions-ammonia, amides, and nitrates-but low in reducing sugars as compared with plussulfur stems. 3. The above results agreed well with those of previous studies by the writer on the effects of sulfur deficiency on soybean, sunflower, and black mustard and in most respects with data of Nightingale et al. for tomato plants grown at New Brunswick, New Jersey. Their results differed in two main respects from those obtained by the writer. They found that the lower leaves became chlorotic first and that reducing sugars accumulated in minus-sulfur stems along with other carbohydrates. 4. It is concluded that variations in atmospheric conditions probably accounted for difference...

Es wird uber eine Farbreaktion berichtet, die nach den bisherigen Untersuchungen zur Unterscheidung zwischen unraffinierten und raffinierten Sonnenblumenolen geeignet ist. Der qualitative Nachweis der farbgebenden Substanz last sich uber das Unverseifbare fuhren, er gelingt aber auch nach entsprechender Anreicherung mit dem Ol direkt. Unter den gewahlten Versuchsbedingungen zeigen Presole auf dem Dunnschicht-Chromatogramm nach dem Bespruhen mit Antimon (III)-chlorid kurz oberhalb des Startpunktes zwei blaue Zonen mit ahnlichem Rf-Wert. In raffinierten Sonnenblumenolen fehlen die blaufarbenden Substanzen, die sich bisher als Keto-Sterine erwiesen haben. Investigation and Adjudgement of Sunflower Oils of Natural Purity Colour reactions, which were employed till now and found suitable for differentiating unrefined from refined sunflower oils are reported. The qualitative detection of the substances responsible for the colour reaction can be carried out with unsaponifiables, however, it is also possible to use the oil directly after a certain enrichment. Under the experimental conditions chosen, and using antimony trichloride spray the pressed oils give two blue spots with similar Rf-values on the thin-layer chromatogram located slightly above the start. These substances giving a blue colour, which were found to be keto-steroids, were absent in refined sunflower oils.

Helminthosporol, a metabolic product of Helminthosporium sativum, remarkably stimulated elongation of the second leaf sheath of rice seedlings of various varieties. It also stimulated the elongation of hypocotyls of cucumber seedlings. This substance did not have any effect on the growth of peas, tomato, sunflower and the dwarf mutants of maize. This substance did not have auxin-like activities.

Little work has been reported on the effect of different temperatures upon the growth of excised root tips in sterile nutrient solutions. White (6) working with root tips of wheat found the optimum temperature for their growth to be between 26? and 27? C. This investigation was undertaken to determine the effect of different temperatures upon the growth behavior of excised root tips of dent corn, cotton, sunflower, and Burpee's Extra Early pea.

Similar changes occurred in the ultrastructure of host cell organelles in the rust-infected tissues of both flax and sunflower. Up to the onset of sporulation at 8 days after inoculation the only major alteration in cell structure was a marked tendency for the cell organelles to be aggregated around the intracellular fungal haustorium and an accumulation of starch in the plastids. During sporulation, however, some striking changes occurred in the structure of plastids, mitochondria, and microbodies. Eleven days after inoculation, in a zone of host tissue adjacent to the rust pustule, the plastids no longer contained starch and varied in structure even within a single cell. Some were similar to normal chloroplasts, others had larger grana, and some bore a close resemblance to chromoplasts. In sunflower, but not in flax, mitochondria contained atypical plate-like cristae in addition to the usual vesiculate type. The micro-bodies of both plant species all contained crystalline cores in contrast to earlier stages in the disease where crystals were only occasionally detected. The plastids were also altered considerably in another zone of tissue situated beneath the rust pustule. In some plastids the thylakoids extended along their long axis, forming several large grana, and in others the large grana were interconnected by lamellae arranged in a vesicular or tubular configuration. Frequently the starch grains in these plastids were broken down into small rosettes of darkly staining particles with an appearance similar to that of animal glycogen.

Diffusible-gibberellin yields in agar from green sunflower apical buds fell within 40 hr of excision of the buds when they were incubated on 1.5% agar. Incubation on agar containing either 2.0% sucrose or 0.1% mevalonate allowed continued gibberellin production by the buds for at least 72 hr. Mevalonate was more effective than sucrose as a stimulant of gibberellin synthesis. Gibberellins obtained from the buds did not appear to be products of wounded tissues at the cut stem surface, but represented normal gibberellin biosynthesis by bud tissues.

Single attached leaves of sunflower (Helianthus annus L. "Mennonite") were supplied (14)CO(2) of constant specific radioactivity in gas mixtures containing various CO(2) and O(2) concentrations. The (14)CO(2) and CO(2) fluxes were measured concurrently in an open system using an ionization chamber and infrared gas analyzer.The rate of photorespiration (5.7 +/- 0.3 mg CO(2).dm(-2).(-1)) during photosynthesis in 21% O(2) at 25 C and 3,500 footcandles was over three times the rate of dark respiration and was independent of CO(2) concentrations from 0 to 300 mul/l. The steady rate of CO(2) evolution into CO(2)-free air was about 30% lower. Low oxygen (1%) inhibited both (14)CO(2) and CO(2) evolution, both during photosynthesis and in CO(2)-free air in the light.At 300 mul/l CO(2) apparent photosynthesis was inhibited 41% by 21% O(2). Two-thirds of the inhibition was due to the inhibition of true photosynthesis by oxygen and one-third due to the stimulation of photorespiration. At 50 mul/l CO(2), where the percentage inhibition of apparent photosynthesis by 21% oxygen was 92%, photorespiration accounted for two-thirds of the total inhibition.The rate of (14)CO(2) uptake by the leaf decreased about 30 seconds after the introduction of (14)CO(2), indicating that (14)CO(2) was rapidly evolved from the leaf. The rate of (14)CO(2) evolution increased rapidly with time, the kinetics depending on the CO(2) concentration. The high specific radioactivity of the (14)CO(2) evolved during photosynthesis or in the early period of flushing in CO(2)-free air showed that the substrate for light respiration was an early product of photosynthesis. From the measurement of (14)CO(2) and CO(2) evolution into CO(2)-free air over a longer time period it was apparent that at least three compounds, each of decreased (14)C content, could supply the substrate for light respiration.Based on a consideration of the specific radioactivity of (14)CO(2) evolved under a variety of conditions, it is suggested that total CO(2) evolution in the light or photorespiration is composed of two processes, dark respiration and light respiration. Light respiration is a process that only occurs in the light, persists for some time on darkening, and metabolizes substrates that are quite different from those of dark respiration.

CCC was shown to be effective in retarding stem growth of sunflower; this effect was overcome by gibberellic-acid application. Using an agar-diffusion technique, the gibberellin (GA) content of sunflower apices treated with CCC was found to be significantly reduced as compared to controls. Similarly, the GA content of agar diffusates obtained from 2-day-old sunflower root tips treated with CCC was also significantly reduced as compared to controls.Root exudate or bleeding sap obtained from mature CCC treated sunflower plants contained no measurable GA-like substance, although it could not be argued that this was due to suppression of GA synthesis in the root systems.