Ângela Maria Cangiani Furlani

Kinetics of phosphorus uptake and root morphology of local and improved varieties of maize

Interspecific and intraspecific differences in the efficiency of utilization of soil phosphorus (P) are explained, in part, by plant morphological and physiological variations, which characterize the plant for nutrient acquisition. As part of a study on maize genotypes characterization for P-uptake and use efficiency, kinetic parameters of P uptake and root morphological characters were evaluated for six local and improved maize varieties, grown in nutrient solution. The kinetic parameters related to P influx were: maximal transport rate (Vmax), the Michaelis-Menten constant (Km), and the external concentration when net uptake is zero (Cmin). Measured root morphological characters were: root length, radius, and surface area. Shoot and root dry matter yield and the P content in these parts were also determined. Diferences among varieties were observed in the kinetic parameters Vmax and Km, root length and in root/shoot dry matter ratio. Lower Km values were better indicatives of P uptake ability of the varietes and were significantly correlated to higher dry matter production and P-efficiency index.

Efficiency of maize cultivars for zinc uptake and use

Zinc deficiency usually occurs in maize grown in Brazilian acidic soils. The aim of this study was to evaluate commercial maize cultivars for their Zn uptake and utilization efficiency. A greenhouse experiment using nutrient solution with young plants was carried out at Campinas, State of Sao Paulo, Brazil, in 2002. Treatments consisted of: 0.0; 0.1; 0.2; 0.4 and 0.8 mg L-1 Zn in the main plots and 24 commercial maize cultivars in the subplots, in a randomized complete block design. Zn concentration in shoot dry matter (SDM) ranged from 28.4 to 41.6 mg kg-1 among cultivars, clearly indicating a dilution effect, since a negative relation between SDM and plant height was shown. Total Zn-shoot content was a good parameter to discriminate cultivars, once correlated with plant height and SDM (r = 0.66** and r = 0.67**, respectively). Analysis of variance and polynomial regression for total Zn-shoot content was highly significant among cultivars and for the interaction cultivar vs Zn-concentration. Plants under low Zn presented up to three-fold differences among efficiency index values (E.I. = 8.59 to 26.42 mg2 DM mg-1 Zn). The results with young plants indicated six maize cultivars classified as Zn-efficient and responsive (AG 7575, Tork, AL Bandeirante, AL 34, AGN 2012, Master) and six cultivars classified as efficient non-responsive (P30F33, P30K75, P30F80, AS 1533, DOW 8420 e AL 30). Other nutrient concentrations in the SDM were within normal limits (K, P, Ca, Mg, Cu, Fe, Mn) for maize young plants.

Crescimento de orquídeas epífitas in vitro: adição de polpa de frutos

THE PULPS OF FRUITS IN THE GROWTH OF EPIPHYTIC ORCHIDS This work was carried out with the aim of studying the effect of pulp of fruits on the growth of orchids seedlings in vitro . Three species of epiphytic brazilian orchids were used: Laelia longipes Rchb.f., Laelia tenebrosa Rolfe e Miltonia spectabilis (Lindley). The following nutritive media were tested: 10:10:10 (N:P:K), at 1 gL -1 , 10:30:20 at 1 gL -1 , apple pulp, at 10 gL -1 , tomato pulp at 10 gL -1 , banana pulp at 50 gL -1 , and also the KNUDSON, VACIN and WENT, MURASHIGE and SKOOG (MS) media. In seedlings of L. Longipes cultivated in 10:10:10 and banana pulp was observed higher accumulation, and the lowest one in MS. Analysis of dry mass results for Miltonia spectabilis showed that the media 10:30:20 and banana pulp propiciated the highest dry mass accumulation and the MS medium, the lowest. In decreasing order of total dry mass accumulation are the media 10:30:20 and banana pulp, followed by 10:10:10, tomato pulp, KNUDSON (58,3%), VACIN e WENT (18,7%), apple pulp (13,2%) and MS (4,1%). For Laelia tenebrosa, seedlings cultivated in banana pulp incorporated higher dry mass content, followed by those cultivated in 10:10:10, whereas the remaining media propitiated reduced accumulation.

Quest of Water Extract Analysis of Micronutrients in Soilless Organic Substrates

Abstract This research was aimed at evaluating the current water extraction methods for the analysis of four substrates treated with and without micronutrients. Black peat, coir, rice hulls, and pine bark (Pinus elliotis) were treated as follows: 1) control, 2) nitrogen, phosphorus, and potassium (NPK), and 3) NPK+M (micronutrients). Substrate samples were collected at 20 and 120 days of incubation for the determination of micronutrient concentrations. After 120 days of incubation, B, Mn, and Zn were easily detected in the SE, 1:1.5 v/v, and 1:2 v/v extracts from treatments with added micronutrients. Cu and Fe concentrations did not differ among treatments, irrespective of the extraction method used. Pine bark and black peat showed the lowest micronutrient concentrations for B and Zn; coir showed high values for B, Fe, and Zn concentrations; and rice hulls showed the highest Mn and Zn concentrations. SE and the 1:1.5 water extract were the best methods for substrate micronutrients evaluation.