Effects of stubble leaf removal and frequent cutting on nitrogen fixation and regrowth of phasey bean

Wan Mohamad Wan Othman, . and Asher C.J., . Effects of stubble leaf removal and frequent cutting on nitrogen fixation and regrowth of phasey bean. pp. 39-49. ISSN 0126-8643

Plants of phasey bean Macroptilium lathyroides (L.) Urb. cv. Murray were grown to early flowering (20 percents) stage in a nitrogen-free nutrient solution. The plants were left uncut (leaf area of 607 centimetres squares/pot) or cut once on Day 0 at a high (node 10) or low (node 5) level with all stubble leaves (leaf area 311 and 68.3 centimeters squares/pot respectively) retained or removed. Flowers and flower buds remaining only on the tall stubble were retained. In another treatment plants were cut thrice (Days -12 -6 and 0) at progressively decreasing heights. Nitrogenase activity (acetylene reduction assay) of nodulated root systems nitrogen accumulation in pods and new shoots dry matter yields of plant parts and leaf areas were determined on four occassions over the next 25 days. Compared with the uncut control high or low level cutting significantly reduced nitrogen fixation nodulation and root growth and these detrimental effects were further deteriorated by stubble leaf removal or by frequent cutting. A reduction of 49 to 100 percents in leaf area caused a 71 to 96 percents reduction in nitrogenase activity within 24 h of defoliation. Nitrogenase activity subsequently increased with the growth of new shoots only with low level cutting. Although root growth nodule mass and nitrogen fixation were greater following high level cutting shoot regeneration on the tall stubble was slower than on the short stubble. The suppressed vegetative regrowth following high cutting was associated with the diversion of nitrogen to the developing pods which initially formed stronger nitrogen sinks than new shoots. The relevance of nitrogen fixation and partitioning to regrowth of basinodal flowering nodulated annual pasture legumes after cutting is highlighted

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Abstract

Plants of phasey bean Macroptilium lathyroides (L.) Urb. cv. Murray were grown to early flowering (20 percents) stage in a nitrogen-free nutrient solution. The plants were left uncut (leaf area of 607 centimetres squares/pot) or cut once on Day 0 at a high (node 10) or low (node 5) level with all stubble leaves (leaf area 311 and 68.3 centimeters squares/pot respectively) retained or removed. Flowers and flower buds remaining only on the tall stubble were retained. In another treatment plants were cut thrice (Days -12 -6 and 0) at progressively decreasing heights. Nitrogenase activity (acetylene reduction assay) of nodulated root systems nitrogen accumulation in pods and new shoots dry matter yields of plant parts and leaf areas were determined on four occassions over the next 25 days. Compared with the uncut control high or low level cutting significantly reduced nitrogen fixation nodulation and root growth and these detrimental effects were further deteriorated by stubble leaf removal or by frequent cutting. A reduction of 49 to 100 percents in leaf area caused a 71 to 96 percents reduction in nitrogenase activity within 24 h of defoliation. Nitrogenase activity subsequently increased with the growth of new shoots only with low level cutting. Although root growth nodule mass and nitrogen fixation were greater following high level cutting shoot regeneration on the tall stubble was slower than on the short stubble. The suppressed vegetative regrowth following high cutting was associated with the diversion of nitrogen to the developing pods which initially formed stronger nitrogen sinks than new shoots. The relevance of nitrogen fixation and partitioning to regrowth of basinodal flowering nodulated annual pasture legumes after cutting is highlighted

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Item Type:	Article
Additional Information:	3 ill.; 2 tables; 23 ref.; Summaries (En Ms)
AGROVOC Term:	MACROPTILIUM LATHYROIDES
AGROVOC Term:	FLORACION
AGROVOC Term:	NITROGENO
AGROVOC Term:	ETAPAS DE DESARROLLO DE LA PLANTA/ REBROTE
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:56
URI:	http://webagris.upm.edu.my/id/eprint/20453

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