Morpho-physiological responses of guar [Cyamopsis tetragonoloba (L.) Taub.] to multiple stresses of drought, heat and salinity

Abstract

Plant responses to abiotic stresses such as drought, salt, and heat, have been studied separately, but in fact, plants are exposed simultaneously to a combination of stresses. Therefore, the objective of this study was to explore the morphophysiological responses of the guar plant to the combination of heat, drought, and salinity with respect to that to an individual stress. Five treatments including heat, drought, salinity, a combination of multiple stresses and control were applied to two guar accessions namely "BWP-5595" and "24320". The results showed that heat stress enhanced biomass, plant height, leaf number, leaf elongation, and prolonged time to flowering. However, it reduced root length and water use efficiency, but it had moderately negative effect on leaf area, stomatal conductance and number of pods. Contrastingly, drought stress improved root length, water use efficiency, and leaf elongation. It affected negatively leaf area, plant height, and prolonged days to flowering. Drought stress moderately reduced leaf number, biomass, stomatal conductance, and number of pods. Comparatively, salinity stress had a moderately negative impact on all studied traits except leaf number, which was reduced significantly. However, the combination of multiple stresses severely affected all studied traits except water use efficiency. These results show that the adverse effects of the combination of all three stresses were more pronounced than those of either of the individual stresses. Of the two guar accessions used, BWP 5595 showed better performance than accession 24320 in most of the traits measured. This indicates that the effect of multiple stresses differs among the accessions of a species.

Physiological Responses of Indigenous Vegetable of Sintrong (Crassocephalum crepidioides) due to Exposure to High Temperature

“…The high temperature inside the leaves results in a decrease in stomatal conductance in olives and this decrease in stomatal conductance aims to minimize the risk of xylem embolism. Similar to the study on Cyamopsis tetragonoloba with a high temperature of 42 °C, the stomatal conductance value was reduced to 45 mmol m -2 s -1 , lower than the control of 49 µmol CO2 m -2 s -1 (Alshameri et al, 2019). At high temperatures, low water availability and high evapotranspiration favor a decrease in stomatal conductance because a higher transpiration rate results in lower xylem vessel pressure (Haworth et al, 2018).…”

Drought Stress Response in Guar (Cyamopsis tetragonoloba (L.) Taub): Physiological and Molecular Genetic Aspects

“…Another drought-tolerant guar variety, BWP-5595, also demonstrated increased expression levels of three genes of the SWEET (Sugars Will Eventually Be Exported Transporter) family of sugar transporters [27,72]. This fact is also in line with the proposed concept.…”

“…Thereby, the number of pods per plant was most negatively affected by drought, whereas the number of seeds per pod appeared to be the least responsive trait [15,24]. The experiments of Alshameri and co-workers [27] accomplished in Pakistan showed that the drought-induced decrease in the number of pods formed was accompanied by a drop in the number of leaves, leaf area, leaf dry weight, total shoot biomass and plant height.…”

Salinity responses in 24 guar genotypes are linked to multigenic regulation explaining the complexity of tolerance mechanisms in planta

“…In a salinity study, irrigation with saline water with EC iw of 9 dS m −1 resulted in an average reduction in yield by 63% compared to the control (Suthar et al., 2018). The comparison of seed germination and seedling growth also revealed diverse salinity responses of genotypes (Rasheed et al., 2015; Suthar et al., 2019). The salt tolerance index (STI) for shoot biomass, representing the performance ratio under salinity to control, was 1.35 and 1.58 for salt‐tolerant genotypes and 0.21 and 0.20 for salt‐sensitive genotypes (Sandhu et al., 2021).…”