were significantly reduced in the PlusN treatment of both the irrigated and nonirrigated environments, N concentration was not significantly different between N treatments in the irrigated environment (3.37 vs.
Sinclair and Serraj (1995) reported that warm-season species that accumulated high concentrations of ureides
(>200 mmol [L.sup.-1] xylem sap) were more drought-sensitive than species with <50 mmol [L.sup.-1] xylem sap or no ureide
The procedure for ureide
analysis was as described by Young and Conway (1942) with minor modifications (Streeter, 1979).
and N[O.sup.-.sub.3] were extracted from petioles in 1.25 mL of 0.2 M NaOH at 100[degrees]C for 30 rain (de Silva et al., 1996).
Involvement of ureides
in nitrogen fixation inhibition in soybean.
There are at least two possible hypotheses based on degradation of ureides
in the leaves as water deficits develop to explain the low ureide
concentrations in Jackson.
were extracted from approximately 25 mg of dried nodule or leaf tissue in 1.25 mL of 0.2 M NaOH for 30 min at 100 [degrees] C, and concentrations were determined colorimetrically using the procedure of Young and Conway (1942) modified as previously described (de Silva et al., 1996).
It was hoped that in the Stage 1 screen that soybean germplasm might be identified which contained no petiole ureide
because those legume species with high tolerance of [N.sub.2] fixation to soil drying appear not to transport ureides
from the nodules (Sinclair and Serraj, 1995).
and amides as N sources for soybean seed growth and maturation in vitro.
The rapid decrease in ARA in response to allantoin indicates the inhibitory nature of ureides
on nodule activity.
[plant.sup.-1] mg [nodule.sup.-1] Jackson 93 3.71 ** KS4895 158 ** 2.18 avg ([dagger]) 132ns 3.40 * avg 119 2.50 Shoot ureide
Acetylene reduction Cultivar Conc.
Role of amides, amino acids, and ureides
, in the nutrition of developing soybean seeds.