Flowering and Growth Response of Peanut Plants (Arachis hypogaea L. var. Starr) at Two Levels of Relative Humidity.

Peanut plants (Arachis hypogaea L. var. Starr) grown under two different relative humidities were used in all experiments. All plants were germinated and grown to flowering in the greenhouse. At this time, one group was moved to a growth room under 95% relative humidity. After 50 days the humidity of the growth room was lowered to 50%. The second group was moved into a growth room at 50% relative humidity and after 50 days the humidity was raised to 95%.Flowering rates of plants under high humidity were greater than rates of those plants under low humidity. Flowering was stimulated by transfer from low to high humidity, and these plants set the largest percentage of pegs, maintained a high rate of ethylene production by 2-centimeter peg sections, a high growth rate of intact pegs, and they had a higher mean content of gibberellins than plants transferred from a high to a low humidity. The plants in the high to low transfer had the least number of flowers, formed the lowest percentage of pegs, had about 50% less ethylene production by 2-centimeter peg sections, and the peg growth rate declined about 50%.Maximum ethylene production occurred during initial stages of peg growth (1- to 5-millimeter sections), and gibberellin content was generally higher in these peg sections. Thus, high humidity enhanced flowering, peg formation, and peg growth rate. A causal relationship between these effects of high humidity and the growth regulator status of the developing fruit is indicated.