Temperature Effects on Vegetative and Reproductive Development of Peanut¹,²

Abstract

Optimum temperature for growth of most peanut (Arachis hypogaea L.) genotypes is near 30°C. During the 1980 growing season, temperatures ranged from 35 to 40°C for many days in USA peanut producing regions, and severe crop losses attributable to the high temperatures and drought occurred. Experiments were initiated to determine the effect of temperature separate from drought on peanut development. Plants were grown in controlled environments at 30/25°C, 12/12 h light/dark temperatures to obtain a population of plants with uniform development. Measurements of individual leaf areas, leaf dry weights, and seedling height were made 21 days after planting to establish plant growth state. Then temperature treatments, based on temperatures expected to occur during the summer peanut growing season in the southwest USA, were begun. Temperature during the dark period was held constant at 22°C for all treatments. Temperatures during the light period were 30, 32, and 35°C. The 35°C treatment decreased individual leaf areas and dry weights at both 63 and 91 days after planting. Plants harvested at 91 days after planting showed reduced total leaf area and stem elongation was decreased in two experiments at 35°C. The highest temperature treatment significantly reduced the number of subterranean pegs. Mature seed weight was reduced and significantly so in two of three experiments, once for each cultivar tested. Thus, a temperature of 35°C was shown to have an inhibitory effect on peanut development even when plants were grown under well‐watered conditions. An evaluation of eight peanut genotypes showed genotypic variation in response to the 35°C temperature treatment. Selection for peanuts with improved heat tolerance may be possible.

Efficient Partitioning of Assimilates in Stress-Tolerant Groundnut Genotypes under High-Temperature Stress

“…Exposure to hot day temperatures of 35 • C and above continuously for six days relative to 28 • C reduced flower production by about 50% [26]. Day temperature above 35 • C during reproductive phase reduces fruit set and, consequently, the number of pods and ultimately seed yield [26,27]. In the present study, groundnut genotypes were exposed to different temperature regimes during flowering period, with increasing temperatures from E1 to E3 (Figure 1).…”

“…In E1, the flowering was spread over a period of 25 days with maximum temperature reaching up to 34 • C, except for three days (45,52 and 53 days after planting (DAP)) when the temperature was 35 • C or above ( Figure 1a). In E2, on all the days of the flowering period, except five days (27,28,29,30 and 43 DAP) the temperature was 35 • C or above for ca. 3-8 h in a day (Figure 1b).…”

“…Studies have shown that the reduction in pod yield at higher air temperatures is a consequence of the decrease in fruit set resulting from fewer pegs and pods [10,40,41]. From controlled environment studies, Ketring [27] showed that the numbers of pegs and pods were reduced by 33% by an exposure to a day temperature of 35 • C compared with 30 • C. Ntare et al [24], based on his field study, reported more than a 50% decline in pod yield when flowering and pod formation occurred at maximum temperature of 40 • C. Significant reduction in kernel mass due to heat stress to an extent of 45-46% was observed in heat-stress environments, E2 and E3 compared to non-stress environment, E1. It may be possible that kernel mass reduction, in part, may have contributed to pod yield reduction under heat stress, besides other factors.…”

“…On the contrary, pod yield reduction of ca. 18-26% due to high air temperature was reported [6,[26][27][28][29]47]. …”

Phenotypic diversity in cold-tolerant peanut (Arachis hypogaea L.) germplasm

“…Peanut production environments are characterized by a warm, frost-free period of at least 90 days (Bunting et al 1985), with mean temperatures between 24°C and 33°C, which is the optimum range for growth and dry-matter production (Ketring 1984). The peanut plant shows maximum growth at 28°C but experiences severe metabolic perturbations below 12°C (Bell et al 1994a).…”