Controlled Environments as an Adjunct to Field Research on Lentils (Lens culinaris). V. Cultivar Responses to Above- and Below-average Temperatures during the Reproductive Period

Abstract

SUMMARYNodulated plants of three USA cultivars of lentil (Lens culinaris) were grown in controlled environment cabinets. They were given either 20 or 80 ppm inorganic nitrogen and experienced a mean temperature of 12.3° C during the vegetative period, i.e. until 73–77 days after sowing. Factorial combinations of above- (29°/11° C) and below-average (23°/8° C) day/night temperatures were then imposed, to give four mean temperatures within the range of 16.6° to 21.1° C until reproductive maturity. Post-flowering vegetative dry-matter production and seed yields were dominated by treatment effects on the initiation and growth of branches. Warmer temperatures accelerated progress towards maturity, limited branching and restricted dry-matter production; at a mean temperature of 20° C plants were almost barren. The implications of these and previous data to lentil crop production and to the use of controlled environments in lentil breeding programmes are discussed.

Effect of a Heat Wave on Lentil Grown under Free‐Air CO2 Enrichment (FACE) in a Semi‐Arid Environment

“…In this study, we found that a 3‐d heat wave event at the flat pod stage decreased grain yields in lentil by 33%. Other studies have sometimes reported much greater yield penalties due to heat stress in lentils: Bhandari et al (2016) reported a 92 to 95% decrease in yields from late planting (moving the growing season into hotter conditions); Summerfield et al (1989) reported a 79 to 96% decrease in yields by increasing postflowering daytime temperatures from 25 to 29°C in growth chambers; Delahunty et al (2015) reported a 20 to 100% decrease in grain yield in a screen of 50 lentil genotypes; and a subsequent study showed decreases of 43 to 47% from a 5‐d heat wave (maximum temperature: 42°C) at the flat pod stage, depending on water availability (Delahunty et al, 2017). Except for the latter, these studies have imposed a chronic heat stress rather than an acute short‐term heat stress, such as a heat wave.…”

“…Early reports in growth chambers of the impact of high growing temperatures during pre‐ and/or postflowering stages in lentil in the United States suggested that grain yield was negatively affected by daily mean temperatures >18°C. High temperatures accelerated senescence and restricted biomass production postflowering, which reduced pod set in the indeterminate crop (Summerfield et al, 1989). Sarker et al (2003) also found a negative correlation between temperatures during the pod‐filling period (ranging from 14.2 to 22.6°C) and lentil grain yield in the Near East.…”

Understanding photothermal interactions will help expand production range and increase genetic diversity of lentil (Lens culinarisMedik.)

“…Increases in temperature are expected to cause a decrease in DTF, up until the top end of the optimal temperature range, after which further increases will delay flowering (Summerfield et al., 1991). Additionally, supraoptimal temperatures can also decrease yield related traits such as the duration of the reproductive period and plant height (Summerfield et al., 1989) and cause flower and/or pod abortion (Kumar, et al., 2016). Another predicted scenario is a shift in production regions (e.g., northward) in order to maintain similar temperatures during the growing season, which can change the mean daylength experienced.…”

Understanding photothermal interactions will help expand production range and increase genetic diversity of lentil (Lens culinarisMedik.)

“…Increases in temperature are expected to cause a decrease in DTF, up until the top end of the optimal temperature range, after which further increases will delay flowering (Summerfield et al, 1991). Additionally, supraoptimal temperatures can also decrease yield related traits such as the duration of the reproductive period and plant height (Summerfield et al, 1989) and cause flower and/or pod abortion (Kumar et al, 2016b). Another predicted scenario is a shift in production regions (e.g., northward) in order to maintain similar temperatures during the growing season, which can change the mean daylength experienced.…”