No abstract

Field trials were conducted during the wet seasons of 1989, 1991, 1994 and 1995 to evaluate the effects of pre-emergence and post-emergence applications of four rates of imazaquin (0.00; 0.15; 0.30 and 0.45kg a.i/ha) on the growth, leaf chlorophyll types and grain yield of soybean c.v. SAMSOY 2. Imazaquin applications had no significant effect on the growth of soybean roots on most of the sampling dates, but pre-and post-emergence applications of imazaquin at 0.30 and 0.45kg a.i/ha reduced soybean root nodules at 5 and 7 weeks after planting (WAP). Soybean shoot growth was generally reduced at 5WAP by the pre-emergence and at 7WAP by the higher rates (0.30 & 0.45kg a.i/ha) of post-emergence application of imazaquin. Pre-and post-emergence applications of imazaquin showed a strong tendency to reduce the concentration of chlorophyll a and total chlorophyll at 3 and 5WAP respectively. The concentrations of chlorophyll types in soybean leaves at 9WAP was generally comparable among most treatments especially in 1991. Whole plant fresh weight of soybean at 7WAP was reduced by all rates of post-emergence application of imazaquin. However, there was no significant difference in the whole plant dry weight of soybean at 3 to 7 WAP in 1989 and at 3, 5 and 9WAP in 1991. In each trial, pre-and post-emergence applications of soybean significantly increased the grain yield of soybean compared with the control treatment. This study showed that, inhibition of soybean shoot growth and leaf chlorophyll concentration was transient and that soybean plants require about 6 weeks for complete recovery from imazaquin phytotoxicity.

No abstract

-(Green algal interactions with physicochemical parameters of some manmade ponds in Zaria, northern nigeria). Green algal species and their association with physicochemical parameters in some manmade ponds in Zaria, nigeria were studied from november 2005 to august 2006. Phytoplankton and water samples were collected, preserved and analyzed using standard methods. a total of 27 green algal species divided into 16 families were recorded. shannon diversity indices ranged from 1.75 to 2.39 in all ponds, dominance index from 0.14 to 0.23 and species evenness 0.56 to 0.64. Closterium sp. and Rhizoclonium hookeri kuetz. were positively associated with the concentration of Fe, however they were negatively correlated (sensitive) to alkalinity, total dissolved solids and electrical conductivity. Stichococcus bacillaris naegeli, Staurastrum rotula nordst. and Sphaeroplea sp. had significant positive relationship with biochemical oxygen demand (BOD), Mn, and Mo levels in the water. Pseudouvella americana (snow) Wille. and Scenedesmus quadricauda (turp.) de Bréb. showed a close positive association with alkalinity but were sensitive to Fe, Bod, Mn and Mo. the species reported here showed closed association with physicochemical factors in these ponds.key words -Chlorophyta, diversity, ecology, lenthic water bodies, trace metals RESUMO -(Interação de algas verdes com parâmetros físico-químicos em lagoas artificiais em Zaria, Norte da Nigéria). As espécies de algas verdes e sua associação com parâmetros físico-químicos em lagoas artificiais de Zaria, Nigéria foram estudados entre novembro de 2005 e agosto de 2006. As amostras de fitoplâncton e de água foram coletadas, preservadas e analisadas usando métodos padrões. Foram registradas um total de 27 espécies de algas verdes divididas em 16 famílias. os indices de diversidade de shannon variaram de 1,75 a 2,39 em todas as lagoas; índice de dominância de 0,14 a 0,23 e a eqüidade de espécies de 0,56 a 0,64. Closterium sp. e Rhizoclonium hookeri kuetz. foram associados positivamente com a concentração de Fe, porém eles foram correlacionados negativamente (sensíveis) à alcalinidade, condutividade elétrica e sólidos totais dissolvidos. as espécies Stichococcus bacillaris naegeli, Staurastrum rotula nordst. e Sphaeroplea sp. tiveram relação positiva e significativa com a demanda bioquímica de oxigênio, e com os níveis de Mn e Mo na água. Pseudouvella americana (snow) Wille. e Scenedesmus quadricauda (turp.) de Bréb. mostraram estreita associação positiva com a alcalinidade, mas foram sensíveis ao Fe, dBo, Mn e Mo. as espécies relatadas aqui apresentaram associação próxima com fatores físico-químicos nessas lagoas.

No abstract

No abstract

No abstract

No abstract