Nodule and Plant Development in Stylosanthes humilis H.B.K.: Symbiotic Response to Phosphorus and Sulphur

Abstract

The effect of phosphorus and sulphur on the initiation and subsequent course of development of effective nodulation was determined for young seedlings of Stylosanthes humilis over the period days 1 1 to 26 from sowing. The plants were inoculated with an effective strain of Rhizobium and grown under controlled conditions in a small amount of nitrogen-deficient soil. Phosphorus had a beneficial effect on the initiation of nodules, which were first detected at day 11 in high-phosphorus plants, but not until day 14 in low. Thereafter, nodule development was greatly enhanced by phosphorus, nodule numbers, volumes and dry weights being increased. Nodule relative growth rates were stimulated from 0 . 3 g/g/day at low phosphorus levels to 0 . 7 g/g/day at high phosphorus levels over days 23-26. The nodules became pink earlier, and developed more rapidly as nitrogen-rich organs, in response to phosphorus. This suggested that from the earliest stages, phosphorus not only promoted the development of an increased mass of nodular tissue but also favoured an effective symbiosis. This enhanced nodule development led to greatly stimulated growth, with increasing amounts of total nitrogen and phosphorus in high-phosphorus plants. The assimilation of nitrogen by the whole plant was increased from 17 mg/g nodule dry weightlday at low to 53 mg/g/day with high phosphorus over days 23-26. Sulphur caused an increase in dry weight, but the response to sulphur mainly occurred late in development and was smaller than the response to phosphorus in the young seedlings of this trial.

Phosphorus regulation of nitrogen fixation in a traditional Mexican agroecosystem

“…Barea et al (1988) report that Rhizobium nodules often contain 2 to 3 times more P per unit of dry matter than the root on which they are formed. Numerous investigators have measured an increase in either nitrogen fixation, nodule weight, nodule nitrogen content, or overall N content of legumes when fertilized with phosphorus (Gates 1974;Graham & Rosas 1979;Singleton et al 1985;Israel 1987;Pereira & Bliss 1987). In this study I searched for a relationship between nitrogen fixation and plant phosphorus status in the field.…”

Effect ofRhizobium inoculation and the application of phosphate on the growth, yield and nitrogen fixation of soybeans

“…This is clearly confirmed by our present investigation. The importance of phosphate in the nutrition of nodulated legumes to improve their growth, yields and N2-fixation has been well documented (Gupta & Sen 1966;Idris et al 1977aIdris et al , b, 1978Gates 1974;Cassman et al 1981;Hart et al 1981;Taha et al 1967;Subba Rao 1976).…”

Effect of Household Solid Waste on Initial Growth Performance of Acacia auriculiformis and Cedrela toona in Mycorrhiza Inoculated Soil

“…Plants engaged in symbiotic N 2 fixation generally have a high requirement for P (Robson 1983;Jungk, 1998), which was mainly contributed by high ATP requirements for nitrogenase function (Ribet and Drevon, 1996;Al Niemi et al,1997), plus P needs for signal transduction, membrane biosynthesis, and nodule development and function (Graham and Vance, 2000). P has been shown to increase plant growth and stimulate nodulation in legumes (Gates 1974;Gates and Wilson, 1974;Robson et al, 1981;Jakobsen, 1985;Israel, 1987;Hellsten and Huss-Danell 2000) as well as in other plants (Ekblad and Huss-Danell 1995;Yang 1995;Reddell et al, 1997). The effects of P on nodulation and nitrogenase activity were often ascribed to a general stimulation via plant growth (Robson et al, 1981;Jakobsen 1985;Yang 1995;Reddell et al, 1997).…”