Mineral nutrition of peas (Pisum sativum L.3, varieties asgrow 40 and okaw

Deficiencies of the macronutrients and boron. The presente work was carried out in order to study: a - The effect of the omission and presence of the macronutrients and boron on the growth of the plants - variety Asgrow 40; b - deficiency symptoms of macronutrients and boron in the same variety; c - the effects of the deficiencies of each macronutrient and boron on the dry matter production and on the chemical composition of the plant-variety Asgrow 40. I - Deficiencies of the macronutrients Young peas plants (Pisum sativum, L.), variety Asgrow 40 were grown in pots containing pure quartz. Several times a day they were irrigated by percolation with nutrient solution. The treatments were: complete solution and deficient solution, in which each one of the macronutrient was omitted as well boron. Soon as the malnutrition symptoms apperared, the plants were harvested and divided into: roots, stalks, inferior and superior leaves, flowers, husk containing the seeds. The dry matter was analysed chemically. Conclusions: 1 - Symptoms of malnutrition were observed for N, P, K, Ca and B; 2 - The omission of the macronutrients and boron affected the dry matter production, excepted for magnesium and or sulphur; 3 - The nutrient content in the dry matter, expressed in porcentages (%) and or parts per million (ppm) in deficient leaves and healthy leaves were:O presente trabalho teve o objetivo de estudar alguns aspectos da nutrição da ervilha (Pisum sativum, L.), variedade Okaw ("Torta-de-Flor-Roxa") e Asgrow 40 no que concerne: 1 - Efeitos das omissões dos macronutrientes e do boro, na obtenção de um quadro sintomatológico das carências, na variedade Asgrow 40. 2 - Efeitos das carências dos macronutrientes e do boro na produção de matéria seca e composição química na variedade Asgrow 40. Sementes de ervilha (Pisum sativum, L.) da variedade Asgrow 40, foram postas a germinar em silica, mantendo-se um teor de umidade adequado. Passou-se a regar as plântulas com soluções nutritivas com omissões dos nutrientes, entre 20 e 25 dias após a germinação. Tão logo se delineou o quadro sintomatológico das carências, as plantas foram coletadas, mensuradas em altura (cm) e peso da matéria seca (g). Divididas em raízes, caules, folhas inferiores e superiores, flores, vagens e analisadas. Os dados mostram que: 1 - As omissões dos macronutrientes com excessão do magnésio e do enxofre, apresentaram sintomas visuais de deficiência características. 2 - A produção da matéria seca foi afetada em todos os tratamentos com omissão de nutrientes, com excessão daqueles nos quais foram omitidos o magnésio e/ou enxofre. 3 - Os teores dos nutrientes expressos em porcentagem e/ou partes por milhão em folhas apresentando ou não sintomas de carências foram

The evolution of saline lake waters: gradual and rapid biogeochemical pathways in the Basotu Lake District, Tanzania

The biogeochemical evolution of solutes markedly alters the chemistry in the closed-basin maar lakes that comprise the Basotu Lake District (Tanzania, East Africa). Examination of 11 (out of 13) lakes in the Basotu Lake District identified two distinct evolutionary pathways: a gradual path and a rapid path. During the course of biogeochemical evolution these waters follow either the gradual path alone or a combination of the gradual and rapid paths. Solute evolution along the gradual path is determined by all of the biogeochemical processes that for these waters appear to be tightly coupled to evaporative concentration (e.g. mineral precipitation, sorption and ion exchange, C0 2 degassing, and sulfate reduction). Rapid evolution occurs when mixing events suddenly permit H 2 S to be lost to the atmosphere. The chemistry of waters undergoing rapid evolution is changed abruptly because loss of every equivalent of sulfide produces an equivalent permanent alkalinity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42881/1/10750_2004_Article_BF00026937.pd