Biogeochemical silica mass balances in Lake Michigan and Lake Superior

Silica budgets for Lake Michigan and Lake Superior differ in several respects. Mass balance calculations for both lakes agree with previous studies in that permanent burial of biogenic silica in sediments may be only about 5% of the biogenic silica produced by diatoms. Because dissolution rates are large, good estimates of permanent burial of diatoms can not be obtained indirectly from the internal cycle of silica (silica uptake by diatoms and subsequent dissolution) but must be obtained from the sediment stratigraphy. The annual net production of biogenic silica in Lake Michigan requires 71% of the winter maximum silica reservoir which must be maintained primarily by internal cycling in this large lake whereas the comparable silica demand in Lake Superior is only 8.3%. The greater silica demand in Lake Michigan is the result of phosphorus enrichment which has increased diatom production. It is hypothesized that steady-state silica dynamics in Lake Michigan were disrupted by increased diatom production between 1955 and 1970 and that a new steady state based on silica-limited diatom production developed after 1970. Mass balance calculations for Lake Michigan show in contrast with previous work that the hypothesized water column silica depletion of 3.0 g · m −3 could have occurred even though 90% or more of the biogenic silica production is recycled.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42471/1/10533_2004_Article_BF02187199.pd

Effects of vernalization and plant regulators on growth and flowering of Lilium longiflorum Thunb

Lily bulbs were held at 22°C or vernalized at 4° or 8°C for two weeks and then soaked for 12 hours in 1,000 ppm gibberellic acid (GA) or 1,000 ppm indolylacetic acid (IAA) before being planted in the field. Treatment of lily bulbs with 4°C for two weeks delayed shoot emergence. This delay by vernalization was removed when bulbs were soaked for 12 hours in 1,000 ppm GA or IAA. Vernalization and plant regulators had no consistent effects on the plant height or on the plant quality. Bulbs vernalization at 4° or 8°C for two weeks reduced the number of stems produced. There were no differences in the dates of anthesis between the treatments. Flower quality was improved by bulb vernalization at 8°C for two weeks or by immersion for 12 hours in 1,000 ppm IAA.Bulbos de lírio foram mantidos a 22°C ou vernalizados a 4º ou 8°C por duas semanas, sendo então imersos por 12 horas em soluções de ácido giberélico (GA) 1000 ppm ou ácido indolilacético (IAA) 1000 ppm, antes de serem plantados em condições de campo. Tratamento dos bulbos a 4°C, durante duas semanas, atrasou a emergência das brotações. Este atraso devido a vernalização foi removido quando os bulbos foram imersos por 12 horas em soluções de GA ou IAA 1000 ppm. Vernalização e fitoreguladores não afetaram a altura nem a qualidade das plantas de lírio. A vernalização dos bulbos a 4º ou 8°C, durante duas semanas, reduziu o número de hastes produzidas. Nao se verificaram diferenças entre os tratamentos em relação ao período de tempo para a ocorrência da antese floral. A qualidade da inflorescência foi melhorada pela vernalização do bulbo a 8°C durante duas semanas ou por imersão durante 12 horas em solução de IAA 1000 ppm

Nutritional plans for boars

The objective of the present study was to evaluate nutritional plans for boars. Four hundred animals of 67 to 135 days of age and initial weight of 27.75±1.61 kg were distributed in a randomized block design with seven nutritional plans for boars (9.0-8.0; 9.0-9.0; 10.0-9.0; 10.0-10.0; 11.0-10.0; 11.0-11.0 and 12.0-11.0 g/kg of digestible lysine from 67 to 107 days and from 108 to 135 days, respectively) with four repetitions and a control plan for barrows (11.0-10.0 g/kg of digestible lysine) with eight repetitions and ten animals each. Uncastrated male swine presented better feed conversion; however they showed a lower marbling degree in relation to barrows, regardless of the nutritional plan. The nutritional plan that corresponds to the sequence of 11.0-10.0 g/kg of digestible lysine from the 67 to the 107 days and from the 108 to the 135 days, respectively, meets the nutritional needs of boars