Stepwise Regression Analysis of Citrus Genotype Under Cold Stress

Abstract

Background: Citrus is among the cold temperature (freezing) susceptible plants. The performance of storage and breeding of horticultural crops is mainly dependent on the correlation among the traits. Objectives: The present study was conducted to identify the physiological and biochemical traits of some citrus cultivars with the greatest influence on stress tolerance and determine the direct and indirect effects of these traits on the median Lethal Time (LT50) using integrated pathway analysis (i.e., stepwise regression and causality coefficient). Methods: Pathway analysis (i.e., stepwise regression and causality coefficient) based on additive models, which is among the robust statistical methods to describe the relationship among the traits, was used to investigate the physiological and biochemical characteristics of four citrus cultivars (i.e., Japanese mandarin, Thomson orange, Ruby Star grapefruit, and Lisbon lemon) at temperature levels (-8, -4, and +4°C) in a completely randomized design with three replications in 2021. Results: The results showed that Japanese mandarin and Thomson orange cultivars had the highest stress tolerance (LT50). The results of the correlation coefficient demonstrated that the highest positive and significant correlations belonged to the LT50 with total flavonoid (0.443**), chlorophyll a with chlorophyll b (0.613**), carotenoid with chlorophyll a (0.929**), chlorophyll b (0.573**), and total chlorophyll (0.849**), relative moisture content with malondialdehyde (0.559**), glycine-betaine with catalase (0.919**), hydrogen peroxide with total flavonoid (0.405**), and catalase (0.611**). Conclusions: The results of stepwise regression for all traits indicated the importance and critical role of total flavonoid, proline, and LT50 characteristics.

Carnauba wax-based edible coatings retain quality enhancement of orange (Citrus sinensis cv. Moro) fruits during storage

“…These results highlight that most parameters were strongly positively correlated, meaning that improvements in one trait can positively and beneficially affect the others. Moreover, a significant and positive correlation between antioxidant activity and MDA levels in different citrus varieties has already been documented in the literature 84 – 86 . Cluster analysis serves as a statistical technique, for grouping the traits or the differentiation of various populations based on a variety of characteristics 87 – 89 .…”

Exogenously applied gibberellic acid and benzylamine modulate growth and chemical constituents of dwarf schefflera: a stepwise regression analysis

“…Coefficient of variation and linear regression are used to determine the relationship of linear changes in two variables, and are very important in plant breeding studies 88 . SalehiSardoei et al 89 reported that there is a significant and positive correlation between ion leakage and water core in citrus cultivars. Correlation among attributes may help plant breeding researchers to indirectly select important stress traits through other traits that are easier to measure 90 .…”

Guijing2501 (Citrus unshiu) Has Stronger Cold Tolerance Due to Higher Photoprotective Capacity as Revealed by Comparative Transcriptomic and Physiological Analysis and Overexpression of Early Light-Induced Protein

“…Moreover, the allopolyploid hybrid has lower photoinhibition (Fv/Fm), less oxidative marker accumulation and greater increases in antioxidant activities under cold and light stress relative to its diploid and doubled-diploid parents [33]. Mandarin is the most cold-tolerant citrus type, showing the least significant down-regulation of photosynthetic parameters and highly efficient antioxidant system under natural chilling stress [34], and C. unshiu shows the highest cold tolerance (−8.4 LT50) with a higher chlorophyll content and lower lipid peroxidation compared with C. sinensis, C. paradise, and C. limon [26,27].…”

“…Actually, plant genotype is the determinant of the potential of cold tolerance, whereas other factors can only modify this potential [23]. According to previous studies of citrus, mandarin is the most cold-tolerant, followed by sweet orange and grapefruit, while lemon and lime are the least cold-tolerant [23,24], and substantial research has indicated that satsuma mandarin (C. unshiu) is the most cold-hardy commercial cultivar [23][24][25][26][27].…”