Data/hora: 15/05/2024 11:28:59

Biblioteca(s): 	Embrapa Cerrados.	
Data corrente: 	11/02/2000	
Data da última atualização: 	11/02/2000	
Autoria: 	FRANCO, A. A.	
Título: 	Acidity factors limiting nodulation, nitrogen fixation and growth of Phaseolus valgaris L.	
Ano de publicação: 	1981	
Fonte/Imprenta: 	Davis: University of California, 1981.	
Páginas: 	144p.	
Idioma: 	Inglês	
Notas: 	Ph.D. Thesis.	
Conteúdo: 	Bean (Phaseolus vulgaris L.) is extensively grown in tropical regions, mostly in developing countries without use of N-fertilizer. However, root nodulation and N2-fixation has been found variable under acidic conditions, when soil is used as growth medium. Conditions and techniques for achieving good nodulation of bean in continuous aerated solution culture were developed. The effectes of pH on uptake and distribution of Mo in bean were studied in greenhouse and growth chamber experiments in soil and solution culture. The effects of pH and A1 on nodule initiation and growth, nitrogen fixation (C2H2- reduction) and shot and root growth studied in solution and sand culture. Growth and nitrogrenase activity of nodule and plant growth in solution culture were at as good as in gravel. However, nodule initiation was restricted to plants inoculated before or immediately after transfer of seedlings to solution and restricted to the roots already present before transfer. Lack of nodumation could not be explained by failure of bacteria to colonize the root or absence of root hairs. There were indications that the P-status of the plant together with a facto or factors that had to accumulate or deplete in solution determined success or failure of nodulation. Daily application of 0.5-1.0 mg n per plant delayed growth and nitrogen fixation slightly, but increased plant growth and alleviated the severe N-deficiency stree before the onest of N2-fication. In six cultivars, Mo uptake in silution culture was little infuenced by pH in the range 4.8 to 5.8. Likewise, in more detailed experiments with the cv. Venezuela 350, there was little or no effect either pH (4.8.-6.3) or temperature (21-31 c) on Mo accumulation or distribution. over a wide range of Mo supply in soil and solucion culture. Mo concentration was always higher in nodules then other plat parts at low external concentrations. On bean cultivar acculated more Mo in stem and seed than five other cultivars. Plants of all cultivars tested accumulated ten times more seed Mo when grown on entisol at Davis, Califonia, than on an oxisol in Brazil. These data confirm that genetic and environmetal controls on seed Mo can be manipulated to help control Mo deficiency. Concentrations of A1 up 83 uM in solution did not affect rrot dry weight, nodule growth and nitrogenase activity of nodules alredy initiated of the two bean cultivars tested (Venezuela 350 and Carioca); while in both cultivars, nodule initiation was restricted by A1 in solution above 33 uM. Shoot growth was restricted by 19 uM A1 in cv. Carioca but in cv. Venezuela 350. Total root length of both cultivars were restricted by 19 uM A1. Decreasing pH from 5.5 to 5.0 or 4.5. in sand culture reduced nodule production of young plants by 90%. Similar results were oberved in solution culture, indicating that evan though A1 toxicity may affect nodulation, the effect of A1 on plat growth and the detrimental effect of pH itself were much more importante in determining the suceses of growth and aerly nodulation of the two bean cultivars studied. 	
Palavras-Chave: 	Growth; Root nodulation.	
Thesagro: 	Acidez do Solo; Crescimento; Feijão; Fixação de Nitrogênio; Nodulação; Phaseolus Vulgaris.	
Thesaurus Nal: 	kidney beans; nitrogen fixation; soil pH.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Cerrados (CPAC)	
Exemplares: 	CPAC - (16180-1) - ADD - TS - -- - T045/81 - FRA - T045/81 - DIS