ISSN:
1432-0789
Keywords:
Gliricidia sepium
;
Isotope dilution
;
Low P soil
;
P use efficiency
;
15N uptake
;
N2 fixation
;
Senna siamea
;
Senna spectabilis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The variation in P uptake and use efficiency and N accumulation by Gliricidia sepium (N2-fixing tree), Senna siamea and S. spectabilis (leguminous non-N2-fixing trees) were examined in the field at Fashola (savanna zone), southwestern Nigeria, using four P rates, 0, 20, 40 and 80 kg P ha-1. Growth of G. sepium and S. spectabilis responded to P application at 24 weeks after planting (WAP) and average yield increases of 58% and 145% were observed by the application of 40 kg P ha-1 for the two species, respectively. Such a P response was not found in S. siamea at 24 WAP and for any of the species at 48 WAP. G. sepium accumulated more P (on average 162%) than S. siamea and S. spectabilis at 24 WAP and had greater root length and a higher percentage of mycorrhizal infection. However, at 48 WAP S. siamea had 2.5 times more P than G. sepium. Differences in the physiological P use efficiency (PPUE) between G. sepium and the non-N2-fixing trees were significant at the 0 P level, being higher for S. siamea (average, 0.61 g shoot mg-1 P) than for G. sepium (0.27 g shoot mg-1 P). G. sepium had a consistently lower atom % 15N than S. spectabilis, while that of S. siamea for most of the time did not differ from that of G. sepium. The reference plant affected N2 fixation extimates, with negative values and a higher variability (CV 60%) associated with S. siamea than with S. spectabilis (CV〈20%). Consequently, S. spectabilis was selected as a better reference plant for measuring N2 fixation in G. sepium. G. sepium fixed on average 35% and 54% of its N at 24 and 48 WAP, respectively. Except at the lowest P rate, percentage and amount of N fixed were not generally enhanced by P application.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00336559
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