and isozyme expression of antioxidant enzymes in cucumber seedlings and to assess the possible protective or reversible effect of exogenous Spd application from the oxidative damage caused by high-temperature stress. Materials and Methods Plant
common in vegetable production, were relatively rare. This study, therefore, investigated what is the induction effect of these exogenous PGRs on tomato seedlings, and whether various chilling-tolerant genotypes of tomato respond differently to these
The trend towards total mechanization of the production of processing tomatoes is creating many new problems. This paper describes one which may become very important as the practice of direct seeding in the field partly replaces the use of transplants.
Natural colonization of tomato transplants (Lycopersicon esculentum Mill. `Supersonic') by ice nucleation active (INA) bacteria was monitored during a warm, dry period in the spring and during a rainy period in the fall. Populations of INA bacteria and freezing temperatures were determined for seedlings on days 1 to 5, 7, 9, 12, and 15 after transplanting. During the spring experiment, plant freezing temperatures ranged from -6.4C to -3.6C. INA bacteria were detected from day 1 after transplant with populations ranging from 6 to 630 cells/g fresh wt. Most plants had detectable levels of INA bacteria after 3 days in the field, but some plants did not have detectable levels after 15 days. In the fall, populations of INA bacteria were similar to spring levels for the first week after transplant. Numbers of INA bacteria were higher and plant freezing temperatures warmer on days 9 through 15 in the fall compared with the same period in the spring.
Laboratory experiments were conducted using plants without INA bacteria. Seedlings with dry surfaces supercooled to lower temperatures than tomato plants with wet surfaces.
control Genetic material. Two sets of genetic material were used to study the genetic control of rain damage. The first included seedling and clonal material. The 23 base parents (four cultivars used commercially in the region and 19 advanced breeding
Damage rating after 1 and 2 weeks CI are shown on Table 1 and Fig. 2 . At 36 h chilling duration, seedling damage on growing point ranged 1.0 to 5.3 (average 2.3), true leaf ranged 1.7 to 7.7 (average 5.1), and cotyledons ranged 1.3 to 9.0 (average 5
) Damaged ‘CK03’ golden kiwifruit shoot revealed by “knife test” with dark discolored phloem, vascular cambial, and primary xylem tissue and necrotic lateral bud. (B) Primary shoot of ‘Hayward’ seedling fuzzy kiwifruit exhibiting basipetal injury trend with
shown in Figure 3B , low-temperature storage in darkness reduced the Fv/Fm of watermelon seedlings, and a significant difference in Fv/Fm between treatments was observed after 4 d of storage, which indicated the damage extent to PSII in grafted
variance in regrowth based on grafter skill, timing, and method. However, acceptable removal of the meristem without damaging the rootstock cotyledons has been a challenge. Preserving the quality of the cotyledons is essential, because cucurbit seedlings
hurricane weather but left in place afterward to grow to maturity, however, damaged by the hurricane. Plants identified as replanted were new seedling transplants that took the place of damaged plants. Twelve plants of each type were included in each plot