Organic and inorganic nitrogen fertilizers sources on soybean growth, seed yield, germinability and storability
1994
Pisithkul, K.
Both PSB-Sy2 and BPI-Sy4 varieties differed in the parameters used but growth rates, total plant N content and pest infestation level were similar. Varietal response to N sources were consistent except during pod filling stage for LAI [leaf area index] and plant MC but such differences did not relate to other growth parameters, pest infestation level and seed yield. Differences in plant height due to N sources were not observed except at three weeks after planting where plants given inorganic N were taller. For subsequent stages, growth response in terms of plant height, LAI, CGR, above-ground and root biomass were similar for all treatments. Inorganic N fertilizer tended to suppress nodulation especially at an early stage but this did not affect accumulation of plant N. No differences among N sources were found for soil N status. Plant biomass N concentration and N content in plant parts, HI [harvest index] NHI [net harvest index], as well as N utilization efficiency in terms of NUE sub B, NUE sub G and NUE sub GN were also not affected by N sources. This apparent lack of differences may be partly due to the relatively high native N of the soil and the short experimental duration (one season). Despite a generally higher plant MC observed for inorganic N, the level of pest infestation was similar to organic N sources. The infestation level was generally low despite no pesticide application. Seed yield and quality did not differ with N sources. Also, carabao manure and Gliricidia leaves had similar effect on all parameters measured except that the former increased plant MC at seed filling stage in PSB-SY2. Results indicated that organic N sources is comparable to inorganic sources for soybean seed production at least in the short term
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