Chlorine, Bromine and Sodium As Nutrients for Sugar Beet Plants

Chlorine, sodium and silicon have long been considered as elements that are possibly essential to the growth and development of sugar beets and other plants. Of these elements Cl has been found just recently by Broyer et al (2) to correct a severe nutritional deficiency of the tomato plant when grown in low halide culture solutions. Raleigh (28) observed enhanced growth of table beets in culture solutions supplied with NaCl instead of Na2SO4 as the source of Na. However, no symptoms attributable to a Cl deficiency were reported by him. Crowther (6) noted that sugar beet plants wilted less when Na was applied as NaCl than when supplied as Na2SO4. Significant responses to chloride additions were observed in nutrient solutions by Lipman (21) for buckwheat, by Eaton (7) for tomatoes and cotton, and bv Kretschmer et al (16) for lima bean fruit. As for Br, it has not been considered as a nutrient favorable to plant growth, even though it has been used repeatedly in ion absorption studies by many investigators for many years. Much has been written about Na in terms of direct and indirect effects upon plant growth (5, 9, 10, 19, 20, 23). As an indirect factor of growth the beneficial effects of Na applications to the soil have been explained frequently as a release of K from the soil, or as promoting better root development (5). These phenomena have been considered of special importance in meeting the K requirements of plants on soils low in K. Quite often too the growth of plants has been increased by the addition of Na salts to soils (4, 5, 8, 17, 36) or to nutrient solutions low in K (12, 24, 35). When plants are high in K, Na responses have been observed (12, 18, 31) but most often these are much reduced or not at all in evidence (4, 17, 18, 22, 35). Direct effects of Na on sugar beet growth in field experiments have been reported for muck soils by Harmer and Benne (9) and Harmer et al (10), for sand cultures by Tullin (32), and for table beets in pot experiments with soils by Larson and Pierre (18). Sodium deficiency symptoms have been reported (32) or described (9) in only a few instances and so far no specific function of Na, not performed by K, has been recorded (17, 19). Yet for the beet, "sodium may almost be deemed an indispensable nutrient element, approaching potassium in importance" (19). Silicon, when added as a silicate to soils, has been