Some Aspects of Phosphate Nutrition in the Root System of Broad Bean (Vicia faba)

An attempt was made, using radiophosphate, to trace the movementof phosphate in the root systems of Vicia faba during the period0 to 2 hours after commencement of uptake. The results showthat phosphate inserted at an isolated point is first distributedabout the root systems of turgid plants and tends to accumulatetemporarily in the lateral roots before large-scale movementup the plant axis begins. This increased concentration in thelaterals, which is not thought to represent metabolic accumulation,is at a maximum at 75 minutes in turgid plants but in wiltedplants it terminates more rapidly. It is affected by potassiumcyanide solutions.     

THE PHYTOTOXIC PROPERTIES OF ALTERNARIC ACID IN RELATION TO THE ETIOLOGY OF PLANT DISEASES CAUSED BY ALTERNARIA SOLANI (ELL. & MART.) JONES & GROUT

Alternaric acid, a metabolic product of some strains of Alternaria solani , is highly phytotoxic. If introduced into the vascular system of cut shoots of tomato or potato, it travels upwards and causes necrotic lesions of the stem, petioles and leaf blades, very similar in appearance to the lesions appearing in some phases of natural attack by A. solani. Alternaric acid also produces similar lesions on plants outside the host-range of A. solani. Associated with the production of visible lesions is a disturbance of the water-balance of shoots. Transpiration is increased and, in spite of a simultaneous but smaller increase in water uptake, this eventually leads to complete desiccation of the shoots. A strain of A. solani known to produce alternaric acid in synthetic culture media produces a substance with similar biological properties when inoculated into tomato fruits. Since other workers have shown that some of the symptoms of A. solani attack are toxigenically induced, it is tempting to suggest that alternaric acid is the toxin concerned. On the other hand, there is no correlation between virulence of strains of A. solani and their ability to produce alternaric acid in synthetic culture media or in tomato fruits. Some highly virulent strains produce little or no alternaric acid under any conditions tested. There is some evidence that other toxins beside alternaric acid are produced by A. solani , not necessarily in the same proportions by all strains.     

The effects of seed production techniques on seed characteristics, seedling growth and crop performance of crisp lettuce

Seed crops of crisp lettuce were produced in three years with and without gibberellin 4 plus 7 (GA₄₊₇) application to the young seedlings. The effects on seed and seedling characters and field performance of harvesting seed at different times, either by shaking out mature seed or by ‘windrow’ harvests, were assessed. Differences between treatments in seed and seedling characters within any one year were relatively small although those treatments producing large seed gave large seedlings and those giving uniform seed gave uniform seedlings. There were no important effects of seed production treatments on field characters in any one year. However, when different years of seed production were compared directly there was a large effect of year of production on seedling establishment and the size and uniformity of seedlings. Application of GA₄₊₇ resulted in heavier and more uniform seedlings in two of the three years. The results suggest that major differences between commercial seedlots occur as a result of differences in the environment rather than in the technique of seed production.     

HUMAN REPRODUCTIVE CLONING: A CONFLICT OF LIBERTIES

Proponents of human reproductive cloning do not dispute that cloning may lead to violations of clones' right to self-determination, or that these violations could cause psychological harms. But they proceed with their endorsement of human reproductive cloning by dismissing these psychological harms, mainly in two ways. The first tactic is to point out that to commit the genetic fallacy is indeed a mistake; the second is to invoke Parfit's non-identity problem. The argument of this paper is that neither approach succeeds in removing our moral responsibility to consider and to prevent psychological harms to cloned individuals. In fact, the same commitment to personal liberty that generates the right to reproduce by means of cloning also creates the need to limit that right appropriately. Discussion of human reproductive cloning ought to involve a careful and balanced consideration of both the relevant aspects of personal liberty – the parents' right to reproductive freedom and the cloned child's right to self-determination.     

Some effects of temperature during seed development on carrot (Daucus carota) seed growth and quality

The growth and development of carrot seeds cv. Chantenay Red-cored Royal Chantenay at day/night temperatures of 20/10°C, 25/15°C and 30/20°C and subsequent seed performance were examined in 1984 and 1985. An increase in temperature from 20/10°C to 30/20°C reduced mean weight per seed by 20% in 1984 and by 13% in 1985. There were no effects of temperature on endosperm + embryo weight, or on endosperm cell number but the weight of pericarp decreased with an increase in temperature. Seeds grown at the highest temperature had the largest embryos and the highest nitrogen, DNA and rRNA content; they germinated and emerged earlier, and gave higher percentage seedling emergence than those grown at the lowest temperature. There were no effects of temperature during seed growth on the rate of imbibition of water by seeds during the germination process.