Role of Roots and Shoots of Soybeans in Tolerance to Excess Soil Zinc¹

Abstract

Reciprocal grafts were used to determine the relative importance of the roots and shoots of soybean (Glycine max L.) in tolerance to excess soil Zn. Grafts, in all combinations, were made between ‘Wye’ (Zn‐tolerant) and ‘York’ (Zn‐intolerant) soybean cultivars. For plants grown at soil pH 6.2 and soil Zn additions of 1.31, 131, and 393 ppm, the results showed that the scion genotype controlled relative Zn tolerance, while the rootstock genotype controlled Zn absorption and translocation. Differences in foliar Zn concentrations were not responsible for differential Zn tolerance of these two soybean cultivars.

Zinc Phytotoxicity

“…Polson and Adams (1970) found bean cultivars differed, and White et ai. (1979a;1979b;1979c) found that soybean cultivars differed in susceptibility, but not by as much as two-fold. Boawn and Rasmussen (1971) compared Zn uptake and phytotoxicity in a range of economic species (Table 1), and Boawn (1971) reported on a field study with leafy vegetable crops grown on neutral pH soil amended with ZnS0 4 • Among the leafy vegetables, spinach and chard accumulated Zn more strongly and were more susceptible than other crops.…”

“…In further experiments of White et al (1979b), reciprocal grafts were made between soybean cultivars with lower or higher tolerance to soil Zn. Tolerance (resistance to yield reduction or chlorosis) was a character of the shoots, not the roots.…”

Cadmium and Zinc

“…Interestingly, variation in tolerance was a property of the scion, while uptake and translocation was a property of the rootstock [191]. Tolerance variation was great enough that one could breed for greater Zn tolerance, but this property has little value in normal agriculture.…”

Grafting as a tool in common bean breeding

“…This corresponds with other studies in soybean and common bean. For example, the scion genotype has been reported to influence seed weight, protein content, days to maturity (Cardwell and Polson 1972) and tolerance of plants to zinc (White et al 1979) in soybean and yield per plant in common bean (Izquiredo and Hosfield 1982) grafting trials.…”