Effect of boron deficiency on some physiological and biochemical aspects during the developmental stages of wheat (Triticum aestivum L.) plant
2002
Nasser, L.E.A. (Alexandria Univ. (Egypt). Biology Dept.) | Aal | A.E.A.
The results of experiment I showed that inhibition of root growth in wheat (Triticum aestivum L. Giza 157) plants transferred to boron-free medium coincided with a major decrease in the ascorbate concentration of root. Under low-boron concentration, in which root growth was partially inhibited, ascorbate concentration declined in proportion to growth rate. Furthermore, the decline in ascorbate concentration was not related to ascorbate free radical (AFR) and dehydroascorbate (DHA) as well as ascorbate oxidase in boron-deficient root. Boron deficiency caused a substantial decrease in leaf area, shoot and particularly root weights and as a consequence a strikingly higher shoot/root ratio compared to boron sufficient plants was obtained. In experiment II, it was found that the proportion of total boron partitioned in different organs was on average, leaves contained 70 % of the total boron content in the whole plant compared to 20 % in the roots and 10 % in the stems. One of the most important effects caused by boron deficiency was the decrease in the nitrate content and some cations such as magnesium, calcium and especially, potassium in the leaf, but nitrate content decreased in a higher proportion than these cations. Nitrate reductase (NR) and ATPase activity of boron-deficient plants was also declined and this decline did not occur in boron-sufficient plants. Moreover, boron deficient plants had much higher starch contents and an appreciable accumulation of hexes and sucrose in the leaves than boron-sufficient ones. Soluble sugars might correct the osmotic imbalance elicited by the low content of nitrate and cations in plants subjected to boron deficiency. In experiment III, data showed that under boron deficiency, the number of grains was 18 per ear and sterility of competent florets was 96 % compared to 44 per ear and 46 % respectively under sufficient-boron plants.
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