1. Plant Nutrients. 2. The Soil as a Plant Nutrient Medium. 3. Nutrient Uptake and Assimilation. 4. Plant Water Relationships. 5. Plant Growth and Crop Production. 6. Fertilizer Application. 7. Nitrogen. 8. Sulphur. 9. Phosphorus. 10. Potassium. 11. Calcium. 12. Magnesium. 13. Iron. 14. Manganese. 15. Zinc. 16. Copper. 17. Molybdenum. 18. Boron. 19. Further Elements of Importance. 20. Elements with More Toxic Effects. General Readings. References. Index.

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Principles of plant nutrition

PATHWAY OF ETHYLENE BIOSyNTHESIS 156 Methionine as an Intermediate ....... 157 S-Adenosylmethionine as an Intermediate 158 I-Aminocyclopropanecarboxylic Acid as an Intermediate . ......... 158 Methionine Cycle ........ 161 Conversion of l-Aminocyclopropanecarboxylic Acid to Ethylene 164 REGULATION OF ETHYLENE BIOSYNTHESIS 167 Regulation in Ripening Fruits and Senescing Flowers ...... 167 Auxin-Induced Ethylene Production 169 Regulation of Ethylene Biosynthesis by Ethylene 169 Stress-Induced Ethylene Production . . . . . . . . 171 Regulation by Light and Carbon Dioxide 173 Inhibitors of Ethylene Biosynthesis : 174 Conjugation of l-Aminocyclopropanecarboxylic Acid to l-(Malonylamino) cyclopropanecarboxylic Acid 178 CONCLUDING REMARKS 180

Ethylene biosynthesis and its regulation in higher plants

Seed dormancy is an innate seed property that defines the environmental conditions in which the seed is able to germinate. It is determined by genetics with a substantial environmental influence which is mediated, at least in part, by the plant hormones abscisic acid and gibberellins. Not only is the dormancy status influenced by the seed maturation environment, it is also continuously changing with time following shedding in a manner determined by the ambient environment. As dormancy is present throughout the higher plants in all major climatic regions, adaptation has resulted in divergent responses to the environment. Through this adaptation, germination is timed to avoid unfavourable weather for subsequent plant establishment and reproductive growth. In this review, we present an integrated view of the evolution, molecular genetics, physiology, biochemistry, ecology and modelling of seed dormancy mechanisms and their control of germination. We argue that adaptation has taken place on a theme rather than via fundamentally different paths and identify similarities underlying the extensive diversity in the dormancy response to the environment that controls germination.

/pdf/seed-dormancy-and-the-control-of-germination-4tdhm2985s.pdf

Seed dormancy and the control of germination

The variation in growth rate with temperature of unicellular algae suggests that an equation can be written to describe the maximum expected growth rate for temperatures less than 40°C. Measured rates of phytoplankton growth in the sea and in lakes are reviewed and compared with maximum expected rates. The assimilation number (i.e., rate of photosynthetic carbon assimilation per weight of chlorophyll a) for phytoplankton photosynthesis is related to the growth rate and the carbon/chlorophyll a ratio in the phytoplankton. Since maximum expected growth rate can be estimated from tempera­ ture, the maximum expected assimilation number can also be estimated if the carbon/ chlorophyll a ratio in the phytoplankton crop is known. Many investigations of phytoplankton photosynthesis in the ocean have included measures of the assimilation number, while fewer data are available on growth rate. Assimilation numbers for Antarctic seas are low as would be expected from the low ambient temperatures. Tropical seas and temperate waters in summer often show low assimilation numbers as a result of low ambient nutrient concentrations. However, coastal estuaries with rapid nutrient regeneration processes show seasonal variations in the assimilation number with temperature which agree well with expectation. The variation in maximum expected growth rate with temperature seems a logical starting point for modeling phytoplankton growth and photosynthesis in the sea.

Temperature and phytoplankton growth in the sea

Auxin: regulation, action, and interaction.

Histological studies on the coleoptile. ii. comparative vascular anatomy of coleoptiles of avena and triticum

During the course of experiments on the metabolisnm of Kalanchoe in short and long days (5, 8,11 ) it was noticed that the leaves of plants induced to flower became red, especially at the apical end and on the underside. Nonflowering plants, i.e. those kept in long days, showed only slight and delayed reddening along the leaf margins. However, it was observed that when the leaves of plants on long day were boiled in HCl, a deep red color developed in the solution. This indicates presence of a leuco-anthocyanidin (1) and suggests that the photoperiod might be causing conversion of this compound to the red anthocyanin. Since the flowers whose formation is induced by exposure to short days are also bright red, it appeared further that the photoperiodic stimulus may exert a systemic effect which would lead to the formation of anthocyanin simultaneously in several parts of the plant. A detailed study was therefore made to determine: A, if the anthocyanins in flower and leaf were the same, or related, B, if the reaction is indeed a true response to photoperiod, C, the nature of the metabolic change involved. Although anthocyanins very commonly appear in the leaves of young growing shoots, especially of woody plants, and also in mature fully grown leaves (autumn colors) their appearance in leaves in direct association with flowering seems to have been less commonly noticed. It is not uncommon, however, for plants with red or blue flowers to develop anthocyanin in the midribs or petioles of the leaves, while those with white flowers do not.

Formation of Anthocyanin in Leaves of Kalanchoe blossfeldiana-a Photoperiodic Response.

RECENT discoveries in the gibberellin series have brought to light a large number of new compounds the activity of which varies widely in different tests1. In particular, Hashimoto and Yamaki2 with tobacco seeds, and Toole and Cathey3 with lettuce seeds, reported that GA4 was much more active than GA3, while Brian et al.1 indicate that GA4 and GA7, which had about equal activity on lettuce seeds, were both more active than GA3. However, the latter group stated that they were “not able to establish a simple relationship between dose and response” in their test. Borriss and Schmidt4 crystallized a gibberellin preparation from cultures of Gibberella fujikuroi which was 30 times as active as GA3 on the germination of Diplotaxus seeds and up to 2,000 times more active than GA3 on seeds of Lepidium ruderale. Later this preparation, first called gibberellin A6 or ‘D’ (ref. 4), was found to be a mixture of GA4 and GA7.

Activity of Gibberellin ‘ D ’ on the Germination of Photosensitive Lettuce Seeds

The Effect of Light on the Uptake and Transport of Indoleacetie Acid in the Green Stem of the Pea

Die Hypothese, dass eine geotropische Reizung von Hafer-Koleoptilen eine Querverschiebung des Wuchsstoffes zur Folge hat, ist mit radioaktiverβ-Indolylessigsaure (Indol-CH2C14OOH) bestatigt worden. Das Verhaltnis der aus der oberen und der unteren Flanke von Koleoptil-Zylindern mit Agarblockchen abgefangenen Indolylessigsaure wurde gleich 40:60 gefunden.

Kenneth V. Thimann

Papers

Histological studies on the coleoptile. ii. comparative vascular anatomy of coleoptiles of avena and triticum

Formation of Anthocyanin in Leaves of Kalanchoe blossfeldiana-a Photoperiodic Response.

Activity of Gibberellin ‘ D ’ on the Germination of Photosensitive Lettuce Seeds

The Effect of Light on the Uptake and Transport of Indoleacetie Acid in the Green Stem of the Pea

The lateral transport of indoleacetic acid-C14 in geotropism.