Hypobaric Control of Ethylene-Induced Leaf Senescence in Intact Plants of Phaseolus vulgaris L.

Abstract

A controlled atmospheric-environment system (CAES) designed to sustain normal or hypobaric ambient growing conditions was partial pressures were maintained at levels approximating normal ambient availability.An unexpected increase in endogenous ethylene was detected within nontreated control leaves 48 hours subsequent to relocation from winter greenhouse conditions (latitude, 42°00" N) to the CAES operating at normal ambient pressure. The longer photoperiod and/or higher temperature utilized within the CAES are hypothesized to influence ethylene metabolism directly and growth-promotive processes (e.g. response thresholds) indirectly.

Ethylene-Induced Chlorosis in the Pathogenesis of Bipolaris sorokiniana Leaf Spot of Poa pratensis

“…The severity may be further promoted by factors that enhance senescence, i.e. short photoperiods and/or blue-biased far-red light (17)(18)(19)20) and exposure to auxin-analog herbicides (12,13 promotive of ethylene generation and/or senescence (9,10,22,27).…”

“…Hypobaric systems utilizing air are adequate for postharvest studies and storage; however, manipulation of endogenous ethylene during pathogenesis in an intact plant requires greater system sophistication to provide adequate light for photosynthesis and essential atmospheric component partial pressures (02, C02) at levels that will not impair growth and development. A recently developed CAES2 with hypobaric capability provides the environmental requirements for manipulation of ethylene in intact plants (18).…”

“…(a) Four inoculated plants were placed in the CAES chambers (18) chlorotic streaking between and connecting lesions on leaves of some plants subjected to 1000 mbar also occurred. Necrotic lesion development and chlorotic halo development showed similar and continued development at 72 and 96 h on inoculated leaves subjected to either pressure treatment.…”

The effect of nonionic surfactants on the endogenous ethylene and chlorophyll content of Poa pratensis leaves infected with Bipolaris sorokiniana

“…Previous studies have illustrated the existence of an ethylenechlorophyll relationship (Purvis and Barmore 1981 ;Stall and Hall 1984;Nilsen and Hodges 1983), but in the present study surfactants did not seem to affect the chlorophyll content of leaves by means of ethylene.…”

Chlorosis of Sequentially Older Leaves of Poa pratensis Induced by Biologically Active Products of Bipolaris sorokiniana

“…Chlorophyll loss from the increase in ethylene ranges from 22 to 63% by 96 h after infection. When the mode of action and/or biosynthesis of ethylene is blocked during pathogenesis there is a substantial decrease in the loss of chlorophyll by infected leaves (Nilsen and Hodges, 1983;Hodges and Coleman, 1984;Hodges, 1990;Campbell, 1993, 1994). There remains, however, a 7-15% loss of chlorophyll that is not prevented by the control of the ethylene.…”