Foliar surfaces characteristics of some weeds and study of the absorption and translocation of 2,4-d in Memora peregrina (Miers) Sandwith.

Author(s)

Cristiane Gonçalves de Mendonça

• Document type: Doctoral Thesis
• Press: Piracicaba. , ilustrações, tabelas.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2004-09-10

Examining board members

Ricardo Victoria Filho; Pedro Jacob Christoffoleti; Robert Deuber; Robinson Antonio Pitelli; Valdemar Luiz Tornisielo

• Advisor: Ricardo Victoria Filho
• Field of knowledge: Agronomical Sciences - Agronomy
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP
• Location: Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz; t632.58; M539c

Abstract

The objective of this research was to evaluate the stomatal density, the percentage of polar and apolar compounds of the epicuticular waxes and to observe the ultra-structural characteristics of the foliar cuticle of Peschiera fuchsiaefolia (A. DC.) Miers, Vernonia polyanthes Less., Vernonia westiniana Less., Memora peregrina (Miers) Sandwith, Tecoma stans (L.) Juss. ex Kunth, Ipomoea grandifolia (Dammer) O’Donell, Ipomoea purpurea (L.) Roth., Euphorbia heterophylla L., Sida rhombifolia L. and Sida glaziovii K. Schum.. Other objective was to evaluate the absorption and translocation of the radiolabelled herbicide 2,4-D in plants of Memora peregrina. The stomatal density was determined by the impression of the foliar epidermis in sheet of glass. The epicuticular waxes were extracted with chloroform and they divided in apolar and polar compounds using a column of silica gel. The ultra-structural analysis was realized using the Scanning Electronic Microscopy. The absorption and translocation of the 14C 2,4-D were evaluated using the 2,4-D alone (DMA 806 BR) or the mixture of 2,4-D plus picloram (DMA 806 BR+Padron), in different time after the applications (1, 2, 4, 8, 24 and 48 hours). P. fuchsiaefolia presented stomatal density of 11.8 and 209.4 stomatas/mm2 of foliar area (adaxial and abaxial), short trichomes in the adaxial surface and 41.9 µg of wax/cm2 being 88.8% of polar compounds. The stomatal density in adaxial and abaxial surfaces of V. polyanthes was 36.5 and 99.7 stomatas/mm2, respectively, and in V. westiniana was 45.2 and 154.9 stomatas/mm2. In leaves of V. polyanthes were removed 31.1 µg of wax/cm2 (15.0% apolar compounds and 85.0% polar compounds), whereas in the specie V. westiniana were extracted 42.9 µg of wax/cm2 (7.6% apolar and 92.4% polar). The specie M. peregrina had 368.0 stomatas/mm2 in the abaxial surface and in to adaxial they were absent, in plants of T. stans were achieved 9.7 stomatas/mm2 in the adaxial surface and 78.2 in the abaxial. The percentage of polar compounds was 58.5% in M. peregrina, with 22,8 µg of wax/cm2 and the plants of T. stans presented 16.8 µg/cm2, being 59.5% of polar compounds. The stomatal density of I. grandifolia was 44.0 stomatas/mm2 in the adaxial and 156.0 in the abaxial and in the specie I. purpurea was 62.8 stomatas/mm2 and 131.2 in the abaxial. The species of the Ipomoea genus had great amounts of polar compounds, unicellular trichomes and epicuticular waxes in the form of ridge in the adaxial surfaces. The stomatal density of E. heterophylla was 140.5 stomatas/mm2 in at adaxial surface and 215.2 in the abaxial, with deposit in the form of crystals and with 46.0 µg of wax/cm2 (48.9% apolar compounds and 51.1% polar). The stomatal density of S. rhombifolia was 101.1 stomatas/mm2 (adaxial) and 212.6 (abaxial) and in S. glaziovii the stomatal density was 118.6 and 187.3 stomatas/mm2. The species S. rhombifolia and S. glaziovii presented great percentages of polar compounds, 75.9% and 62.1%, respectively. The percentage of absorption of the 14C 2,4-D one hour after the application were 8.22% and 9.63%, for the treatments with 2,4-D and 2,4-D + picloram, respectively. The absorption 48 hours after the application was 23.81% in the treatment with 2,4-D and 24.26% with 2,4-D+picloram. In this same interval of time, 98.44% absorbed total stayed in the treated leaf in the treatment with 2,4-D and 99.50% with mixture 2,4-D+picloram, then the translocation of this herbicide was considered insignificant. (AU)