The Effect of Night Low Temperature on Agronomical Traits of Thirty-Nine Pepper Accessions (Capsicum annuum L.)

Abstract

Pepper plants are subject to complex environmental factors including abiotic and biotic stresses in fields, as well as the significant effects of climate changes, including low and high temperatures. Low temperature stress in the growth and development of pepper plants is one of the most critical issues, and directly impacts the crop yield and productivity of pepper plants. Therefore, it is essential to select and breed low temperature-(LT) tolerant pepper (Capsicum annuum L.) cultivars. This research was conducted to assess the agronomical traits of 39 pepper accessions belonging to the chili and bell fruit varieties which were cultivated under two different night temperature set-points: at 15 °C for a suboptimal temperature (CT) and at 10 °C for a low temperature (LT). The plant heights (PH) of most pepper accessions in a LT were significantly decreased compared to those in a CT. The stem diameter (SD) and the length of main axis (LMA) varied depending on the genotypes under LT. Moreover, the number of flowers (NFL), total number of fruits (NFR), fruit yield (FY), fruit fresh weight (FFW), fruit length (FL), fruit diameter (FD), and number of seeds in a fruit (NSF) remarkably declined in a LT compared to in a CT. The evaluated agronomical traits between LT and CT were further applied for the correlation analysis, principal component analysis (PCA), and hierarchical cluster analysis. Notably, the FY trait was correlated with other reproductive traits including NFR, FFW, FD, and FL on the positive directions and thirty-nine LT-treated pepper accessions were clustered into seven groups by the hierarchical clustering analysis. The selected accessions were primarily involved in the positive trends with the reproductive index including NFR, FL, FD, and FFW traits and could be used for pepper breeding programs to develop LT-tolerant cultivars.

Effect of leaf cold damage after chilling temperature treatment on growth and reproductive parameters of chilli pepper plants

“…In the agreement with our previous studies of pepper genotypes under LT condition [24], our current finding also showed that the NFL among pepper accessions showed no remarkable difference between the LCD and NT.…”

“…Effect of LCD within 25% in seedling stage on the subsequent growth stages of agronomical traits showed that it might be critical for recovery of pepper plants and significantly affect the development of some vegetative and reproductive parameters. It is well known that, LT significantly reduces the growth rate of plants [2,8,23,24,29], which was detected in plants with LCD in the present study, where lag behind in growth rate of PH in the percentage ratio than NT plants within 50 DAT was determined. Furthermore, a decrease of value of the differences in development was observed but the ranges depended on accession.…”

“…LCD contributed to increase the index of PFW, but decreased the LMA in both pepper accessions, whereas the index of LMA in pepper accessions might be varied depending on the genotypes under LT condition [24]. Meanwhile, the index of LL was increased only in LCD plants of "PE-J-2", but no differences between LCD and NT plants in both accessions in measurement of the LW were recorded.…”

“…In particular, the effect of the abiotic stress on the reproductive traits is well known in Solanaseous crops [1][2][3]6,26,30], and there is enough information about the effect of the cold damages in juvenile phase on the floral and fruit traits at growth stages of pepper. In fact, recently it was found that the selected pepper accessions under LT condition were primarily involved in the positive trends with the reproductive index including NFR, FL, FD, and TY traits and recommended to utilize for pepper breeding programs to develop LT tolerant cultivars [24].…”

“…However, in literature scares information is available on the influence of the degree of cold damages on the agronomical traits at recovery among pepper exposed to LT in seedlings stage, which makes it difficult to assess cold tolerance potential of each genotype. Recently, multiple methods to screen and understand the mechanism for cold-tolerant genotypes among the Solanaseous crops were validated at different growth stages under low temperature stress condition [18,[20][21][22][23][24]. Moreover, several methods to screen cold tolerant genotypes among the tomato and pepper crops have been developed in early growth stages [11,13,19,25,26].…”