Crescimento e necessidades hídricas de mudas florestais tropicais em diferentes condições de sombreamento

Abstract

In this study, at the second chapter were generated, validated and determined the best mathematical models to estimate leaf area of ten tropical forest species (Tabebuia roseoalba; Tabebuia impetiginosa; Handroanthus crysotrichus; Parkia pendula; Parkia platycephala; Swietenia macrophylla; Myracrodruon urundeuva; Schizolobium amazonicum; Adenanthera pavonina and Cassia fistula) based on linear variables (length and width of the leaves and leaflets) and on the dry matter of leaves collected at Sinop, Mato Grosso between January and March 2014. It was found that: the models with better performance combine the independent variables with themselves; that species with blended leaves are better estimated by models that include the measurement of length and width of the sheet; and to the remaining, measures of length and width of the leaflets. The third chapter evaluated the initial growth of seedlings of the species: T. impetiginosa, T. roseoalba, H. chrysotrichus, P. pendula, P. platycephala and A. pavonina in different lighting conditions, provided by black color shade screens (35, 50 and 83% of radiation attenuation); green, red and blue (52% attenuation), and in the absence of shading (full sun). Were performed nine non-destructive analyzes fortnightly (counting of leaf number and measurement of height and diameter) from 16 days after transplanting (DAT) and six destructive analysis every 21 days (obtaining the dry mass of leaves, stem and root; leaf area and root volume) from 31 DAT. The results showed that: with the increasing of light, occurred a decrease in leaf area of the examined species; the seedlings that grew to full sun had higher allocation of carbon in it roots; seedlings that grew at 83% shading showed higher allocation of dry matter in it leaves, and the different shading levels modified the plant biometric parameters and partition of dry matter between the organs of it. The fourth and final chapter determined the crop evapotranspiration (ETc) and the crop coefficient (Kc) of six forest species (T. impetiginosa, T. roseoalba , H. chrysotrichus, P. pendula, P. platycephala and A. pavonina) on their seedling phase in seven shade conditions (full sun; black screens with 35, 50 and 83% attenuation of radiation and color screens: green, red and blue with 52% attenuation) and the their relation with plant growth parameters. Kc was calculated dividing ETo (reference's evapotranspiration) by ETc, and ETo was obtained by the method of Penman Montheit FAO-56. The ETc values were obtained by determining the volume of water transpirated and evaporated daily by seedlings (difference between the weight of saturated soil and the real). The weighting were held from 12 to 135 DAT, and the seedlings' destructive analysis occurred the at 135 DAT. It was found that increasing the shading percentage provides the decrease in etc and Kc, as well as the addition thereof correlates with increased leaf area, biometric parameters and allocation of biomass. The average values of daily ETc and Kc obtained for each species were: 2,90 mm.day-1 and 0,75 to T. impetiginosa; 2,46 mm.day-1 and 0,63 to T. roseoalba; 2,84 mm.day-1 and 0,74 to H. chrysotrichus; 2,12 mm.day-1 and 0,54 to P. pendula; 2,21 mm.day-1 and 0,57 to P. platycephala and 2,53 mm.day-1 and 0,65 to A. pavonina