Boron deficiencies attributed

The samples with expected compositions led to lower BET areas (typically less than ca. 30 m g ) than the boron deficient samples which exhibited BET area close to 70-80 nf/g (Table 1). These high BET values were attributed to the excess of alumina in the samples. 

Yih et al. (95) studied the boron requirement of pollen-derived tissue from Ginko biloba. They found that lower boron levels in the culture solution caused a reduced rate of cell division with no noticeable efiFect on cell size. The deficient boron level also resulted in a lower level of fructose in the hydrolizable polysaccharide fraction. They observed 23% more cell wall material in boron-deficient tissue. It has also been observed that potato tissue grown with boron sprayed on the foliage contained more phospholipids (96). Shkolnik and Kopman (97) found that the root and apical parts of boron-deficient sunflower plants contained less phospholipids than normal plants. The authors attributed this decrease in phospholipid content to the role boron plays in altering the stmctural organization of cells. 

Different works show that the nutritional status of certain nutrients, such as boron (B), calcium (Ca), nitrogen (N), phosphorus (P) and iron (Fe) can trigger changes in phenolic metabolism. Of these nutrients, B is attributed with a clear and significant effect on the metabolism of these secondary compounds. As we shall discuss below, the relationship between B metabolism and phenolics is complex and depends largely on the sensitivity of the plant to B deficiency or toxicity. 

The mechanism of boron-induced etch rate reduction has been extensively investigated since its first observation in the late 1960s. Several models have been proposed attributing the phenomenon to increased lattice distortion and defect density, or surface passivation, or electron deficiency. As described below, although each of these models provides an explanation of some aspects of the phenomenon, a coherent account for the underlying mechanism is still lacking. 

Fig. 16f has log-log plots of chloride vs. boron. The Louisiana oil-field waters are usually high in B concentration, relative to evaporating seawater. Collins (1975) attributes this to the survival of B in solution until late-stage crystallization. The mine brines are generaUy deficient in B, relative to evaporating seawater, which may be due to the dissolution of halite from the salt deposit. Some of the mine waters do plot near the upward tip of the standard curve, indicating a relatively high concentration of B. 

---