Some effects of nitrate and light intensity on soybean root growth and development

Abstract

A field experiment was conducted to determine the effects of light intensity and nitrate nutrition on soybean (Glycine max (L) Merr.) root growth and development. Relative growth rates, total, root and nodule dry weights, and the rates of increase in the number of roots indicated that nitrogen fixation limited growth relative to that achieved with nitrate and that the response to nitrate increases with light intensity and varies with plant age. Nitrate increased with rate of taproot extension but light intensity had no effect.

Phenology, growth, and yield of field-grown soybean and bush bean as a function of varying modes of N nutrition

“…Imsande (1989) reported that soybean receiving excess amounts of mineral N accumulated less total N than inoculated, well-nodulated plants. In contrast, it has been observed more frequently that crops receiving high rates of applied mineral N produce greater yield and accumulate more N than their symbiotic counterparts (Cassman et al, 1981;Buttery and Stone, 1988;George and Singleton, 1992). Our results agree with the latter reports and indicate there is a real cost, reflected in reduced growth and yield, associated with legumes being symbiotic.…”

Summer squash response to root restriction under different light regimes1

“…In comparison, Buttery and Stone (1988) reported that soybean plant response to increased nitrate was governed by light regime, or in other words, that nitrate nutrition was more important when light was not limiting growth. The apparent greater sensitivity of plants to PAR than to soil conditions such as nutrient supply and root restriction may explain why weed competition studies indicate the shading effect of weeds generally contributes more to yield losses than does root competition (Régnier et al, 1989).…”

Patterns of variability in the diameter of lateral roots in the banana root system

“…It is interesting to note that diameter decreases were more pronounced for roots of higher order. These roots could be penalized in at least two ways in the case of assimilate deficiency: directly because less resources are attributed to them, as shown in several studies (Tester et al ., 1986; Buttery & Stone, 1988; Rogers et al ., 1992; Tatsumi et al ., 1992; Bingham & Stevenson, 1993; Thaler & Pagès, 1996a; Muller et al ., 1998), and indirectly because, as shown here, a decrease in the diameter of the parent roots will result in a decrease in the diameter of their laterals. This case is illustrated in GE, where a decrease, compared with FE, in secondary root diameters was accompanied by a sharper decrease in tertiary root diameters.…”

“…The results of several experimental studies have shown that compensatory growth caused by carbon redistribution occurs in unevenly compacted soils (Gersani & Sachs, 1992; Bingham & Stevenson, 1993; Thaler & Pagès, 1997; Mulholland et al ., 1999; Montagu et al ., 2001; Bingham & Bengough, 2003). Moreover, low carbon availability affects lateral roots more than primaries (Tester et al ., 1986; Buttery & Stone, 1988; Rogers et al ., 1992; Tatsumi et al ., 1992; Bingham & Stevenson, 1993; Thaler & Pagès, 1996a; Muller et al ., 1998). When primary roots are subjected to soil compaction or are truncated, lateral root diameters increase (Schuurman, 1965; Hackett, 1971; Crosset et al ., 1975; Lamond et al ., 1983; Thaler & Pagès, 1997), and this response is probably attributable to increased carbon availability for laterals (Thaler & Pagès, 1997).…”