Translocated heat injury

Abstract

When individual attached leaves of bean, cowpea, cucumber, peach, and Chenopodium were injured by heat (10 seconds at 65[degree] were suitable), adjacent non-heated leaves of these plants were commonly injured by some translocated stimulus which did not apparently injure the intervening tissue. On bean and cowpea, abrasion of the nonheated leaves was almost essential for manifestation of this translocated injury, but similar injury was never caused by abrasion only. The heat dosage for 50% translocated heat injury was about 155 seconds at 55[degree], 30 seconds at 60[degree], 10 seconds at 65[degree], and 3 seconds at 70[degree]. The dosage for translocated heat injury was about 10 x that required for direct injury. Translocated injury still occurred if abrasion preceded the heat by as much as 18 hours, or if abrasion followed heating by as much as 8 hours. Direct heat and the translocated effect of heat were additive in that sub-injurious dosages of each when used alone could be injurious if applied to different leaves of the same plant. Treatments to produce translocated heat injury increased infection of bean by tobacco mosaic virus and of cowpea by peach yellow bud mosaic virus, but decreased infection by bean rust.