LIGHT EFFECTS ON NUTSEDGE (CYPERUS SPP.) RHIZOME TO SHOOT DEVELOPMENT: IMPLICATIONS FOR CONTROL BY SOIL SOLARIZATION.

Authors: Chase, Carlene; Sinclair, Thomas; SHILLING, D. - UNIVERSITY OF FLORIDA; LOCASCIO, S. - UNIVERSITY OF FLORIDA; GILREATH, J. - UNIVERISTY OF FLORIDA

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: ARS-USDA scientists at Gainesville, FL have been investigating the possibility of sanitizing soil by soil heating resulting from the installation of clear, heat-conserving plastics on planting beds several weeks prior to the planting of the crop. This management scheme, commonly referred to as soil solarization, can control weeds by killing their propagules directly and by foliar scorching of weeds that emerge under the film. In field experiments it was noted that nutsedge plants readily penetrated opaque film but only rarely penetrated clear plastic solarization films. Greenhouse and laboratory studies have confirmed that this is due to a change in the pattern of plant development when nutsedge plants detect light under clear films as they emerge from the soil. Leaves develop rapidly and the plants are trapped under the film. Under opaque plastic film, leaf development is delayed until after the sharp rhizomes puncture the film. The trapped nutsedge shoots are killed by foliar scorching, which leads to depletion of tuber reserves. The greatest suppression of nutsedge penetration occurred with thicker, clear mulches that provided mechanical impedance as well as altered plant development.

Technical Abstract: In field studies, nutsedge shoots emerging from the soil under clear films were generally trapped beneath the films. Conversely, in rows that were mulched with black film, nutsedge shoots punctured and emerged through the film. In controlled pot experiments conducted in darkness, yellow nutsedge rhizomes readily penetrated 19 m and 30 m clear films as effectively as opaque films. Thicker clear films and bubble film reduced nutsedge penetration. In the greenhouse and laboratory, nutsedge penetration of transparent polyethylene film was inversely related to irradiance levels when the film was in direct contact with the soil. However, when there was a 5 to 10 mm space between the soil and the film, 30 mol m-2 s-1 of light were as effective as 320 mol m-2 s-1 in reducing the penetration of purple nutsedge. The film penetration by nutsedge appears to be linked to a light-dependent morphological change from rhizome growth to leaf development, which occurs before film penetration with clear mulch and after film penetration with opaque mulch. The alternate sprouting and foliar scorching of nutsedge shoots trapped under clear films can be exploited to deplete nutsedge tubers that occur below soil depths where lethal temperatures develop under soil solarization.