Padrões de floração e frutificação de árvores da Amazônia Maranhense Flowering and Fruiting Patterns of the Maranhense Amazon Rainforest Trees

Estudos fenológicos em nível de comunidades podem facilitar a compreensão do comportamento das espécies diante de alterações nos ecossistemas, além de refletir a distribuição anual de tipos específicos de recursos. Este trabalho buscou definir os padrões gerais e a sazonalidade de floração e frutificação de uma comunidade em duas áreas de floresta na Amazônia Maranhense, uma não perturbada e outra submetida a corte seletivo. A vegetação corresponde às matas de cipós das florestas amazônicas, alternando matas densas e abertas, de alta biomassa. Valores médios anuais de temperatura variam entre 24,5º C e 26,0º C, e entre 1400 mm e 1800 mm de precipitação, com um período seco de 5 a 6 meses, de junho a novembro. Foram analisadas a floração e a frutificação de 89 espécies arbóreas, de agosto de 1994 a junho de 1996. As espécies foram agrupadas em: árvores do sub-dossel, árvores do estrato superior e árvores que ocorrem em ambos os estratos. Foi feita comparação entre grupos (estratos, tipos de floresta e mecanismos de dispersão) e possíveis correlações com a precipitação foram investigadas. Quinze espécies estudadas foram exclusivas do estrato inferior e 63 do estrato superior da floresta; 17 espécies foram registradas apenas na mata nativa e 37 apenas na mata manejada. A maioria das espécies é zoocórica (62,9 %). A floração e a frutificação ocorreram durante todo o ano, com pico de floração de outubro a dezembro e picos de frutificação de março a julho e de outubro a dezembro. Os resultados obtidos demonstram uma grande sincronia na floração e frutificação dos indivíduos, e confirmam a relação entre esses processos e a variação na precipitação ao longo do ano, e que plantas de ambientes diferenciados exibem comportamentos fenológicos diferentes. Os padrões observados foram semelhantes entre as áreas e a outros estudos na Amazônia.<br>Community level phonological studies can facilitate the understanding of species behavior as a result of ecosystem changes, further reflecting on the annual allotment of specific resources. The aim of the present study was to define the general patterns, flowering and fruiting seasonality from a community in two forest areas of the Maranhense Amazon Rainforest: a non-disturbed area and another submitted to selective logging. The vegetation is composed of Amazon forest lianas alternating between dense and open high biomass forest. Average annual temperature varies between 24.5O C and 26.0O C, with precipitation ranging from 1400 mm to 1800 mm, and a dry season between June and November. Flowering and fruiting of 89 species were analyzed from August 1994 to June 1996. The species were grouped as follows: sub-dossal, upper strata, and trees occurring in both strata. Comparison was made between groups (strata, types of forest and mechanisms for dispersal) and possible correlations with rainfall were investigated. Fifteen studied species were solely from the lower strata, and 63 from the upper forest strata; 17 species were recorded only in native forest and 37 in managed forest. Most species (62.9 %) is zoochorous. Flowering and fruiting take place throughout the year with flowering peak from October to December and fruiting peaks from March to July and from October to December. The results showed a great synchrony in flowering and fruiting of individuals, and confirm the relationship between these cases and the variation in rainfall throughout the year, and that plants of different environments exhibit phonological behavior different. The observed flowering and fruiting patterns were similar between the areas and comparable to other studies in the Amazon Rainforest

Influence of nitrogen and sulfur fertilization on quality of canola (Brassica napus L.) under rainfed conditions*

Field experiments were conducted at Cereal Crops Research Institute, Pirsabak, Nowshera, Pakistan, during winter 2003~2004 and 2004~2005 to evaluate the effect of nitrogen and sulfur levels and methods of nitrogen application on canola (Brassica napus L. cv. Bulbul-98) under rainfed conditions. Four levels of S (0, 10, 20, and 30 kg/ha) and three levels of N (40, 60, and 80 kg/ha) and a control treatment with both nutrients at zero level were included in the experiments. Sulfur levels were applied at sowing while N levels were applied by three methods (100% soil application, 90% soil+10% foliar application, and 80% soil +20% foliar application). The experiments were laid out in randomized complete block (RCB) design having four replications. Oil content increased significantly up to 20 kg S/ha but further increase in S level did not enhance oil content. Glucosinolate content increased from 13.6 to 24.6 μmol/g as S rate was increased from 0 to 30 kg/ha. Protein content increased from 22.4% to 23.2% as S rate was increased from 0 to 20 kg/ha. Oil content responded negatively to the increasing N levels. The highest N level resulted in the highest values for protein (23.5%) and glucosinolate (19.9 μmol/g) contents. Methods of N application had no significant impact on any parameters under study