Cucurbit Genetics Cooperative Report 10:7 (article 6) 1987

Chlorosis Induced in Glabrous Cucumber by High Temperature

R. W. Robinson

Horticultural Sciences Dept., New York State Agricultural Experiment Station, Geneva, NY 14456

Glabrous (gl) cucumber plants are sensitive to heat stress. When grown in the field at Geneva, NY gl plants often grow well early in the season but, as temperatures increase in midsummer, their growth is reduced and their leaves develop a mottling that is not due to a virus.

Glabrous plants grown in a greenhouse at 70°(day)-60°F (night) had good growth and development as long as they remained at that temperature regime. When some of the gl plants were moved to a growth chamber at constant 95°F, however, leaves developing subsequently were yellow. The nature of the chlorosis was not determined, but the symptoms were similar to those induced by iron deficiency. Plants dominant for gl did not develop chlorosis of young leaves in the growth chamber.

Glabrous plants returned to the 60-70° greenhouse, after one week in the 95°F growth chamber, resumed normal growth and development. Their newly developed leaves were the same color as those of glplants not exposed to heat stress.

The plants for these tests were grown in Hoagland's nutrient solution, facilitating examination of their root systems. The glplants differed markedly from + plants by having fewer lateral roots and root hairs, suggesting that gl may restrict ion uptake under stress conditions.