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Callose accumulated in the tissues of boron deficient bean and cotton plants, the extent and distribution of which depended on the species. Sieve plates in the phloem of boron deficient bean were characterized by heavy plugs of callose, while the sieve plates of boron deficient cotton were essentially unaffected. Translocation of 14C was, however, drastically reduced in both plants. It is suggested that callose deposition in boron deficient plants is a secondary effect of cellular damage.

Twenty-seven popular South African inbred maize lines, four commercial maize cultivars, two sweet corn cultivars and two grain sorghum cultivars were screened by means of a rapid, semi-quantitative method to determine DIMBOA concentration_ Significant differences were found between inbred lines. Sweet corn cultivars exhibited a relatively high concentration of DIM BOA, while grain sorghum contained a very low concentration. Although differences in concentration between plants cultivated from different seed sizes were found, no definite trend could be established.S. Atr. J. Plant Soil 1984, 1: 99-102 'n Eenvoudige en vinnige metode is gebruik om 27 populere Suid-Afrikaanse ingeteelde mielielyne, vier kommersiele kultivars, twee suikermieliekultivars ,l'ln twee graansorghumkultivars te sif vir DIMBOA-konsentrasie. Betekenisvolle verskille het tussen ingeteelde mielielyne voorgekom. In die suikermieliekultivars het 'n relatief hoe konsentrasie DIMBOA voorgekom terwyl 'n baie lae konsentrasie in graansorghum gevind is. Tussen plante wat van verskillende saadgroottes gekweek is, is verskille in DIMBOAkonsentrasie verkry, alhoewel geen definitiewe tendens vir 'n hoer konsentrasie by plante wat van groot sade gekweek is, gevind kon word nie.S.-Atr. Tydskr. Plant Grond 1984, 1: 99-102

Coal-derived sodium humate was found to stimulate primary root growth of seedlings of cantaloupe (Cucumis melo L.) at 1000mg L -1, lettuce (Lactuca sativa L.) and onion (Allium cepa L.) at 500 and 1000 mg L 1, as well as hypocotyl growth of cantaloupe at 1000 mg L-~. Growth enhancement was not due to release of nutrient elements by the product, and, in the case of lettuce and onion, was not due to increased availability or uptake of mineral elements. Growth stimulation of cantaloupe, however, was dependent on the provision of nutrient solution. Growth stimulation of onion roots under axenic conditions indicated an effect of the humate per se rather than a response mediated via microbial breakdown products.