“…2 A). This decrease in chlorophyll content might be due to reduced activity of ALA synthase enzyme responsible for chlorophyll synthesis or due to increased activity of chlorophyll degrading enzyme, chlorophyllase ( Garg and Singla, 2004 , Singh et al, 2016 ; Mann et al, 2018 ) or the excessive accumulation of Na + in the leaf tissues resulted in an alteration of the chlorophyll pigments, and/or a restriction of its biosynthesis which translates into a chlorosis of leaves ( Yadav et al, 2020 ). Fig.…”
In the era of climate change, decreased precipitation and increased evapo-transpiration hampers the yield of several cereal crops along with the soil salinity and poor ground water resource. Wheat being the moderately tolerant crop face many challenges in the arid and semi-arid regions under irrigated agriculture. In view of this, the study was planned to explore the potential of durum wheat genotypes under salinity on the basis of physiological traits. Experiment was designed as RBD in three replications to evaluate 15 wheat genotypes with moderate saline irrigation (EC
iw
– 6 dS m
−1
) and extreme saline irrigation (EC
iw
– 10 dS m
−1
) along with one set of control (Best available water). Different physiological traits such as water potential (ψ
p
), osmotic potential (ψ
s
), relative water content (RWC), Na
+
and K
+
content were recorded in roots as well as shoots at the reproductive stage whereas photosynthetic rate and chlorophyll content were measured in the flag leaves. A significant variability (p < 0.001) was noted among the genotypes under different stress environments and it was observed that durum genotype HI 8728 and HI 8737 showed less reduction in plant water traits (RWC, ψ
p
and ψ
s
) than the salinity tolerant checks of bread wheat KRL 99 and KRL 3–4. HD 4728 and HI 8708 maintained higher photosynthetic rate as well as higher chlorophyll content under the extreme salinity level of EC
iw
– 10 dSm
−1
. No significant differences were found in root Na
+
in genotypes KRL 99 (3.17
g
), KRL 3–4 (3.34
g
) and HI 8737 (3.41
g
) while in shoots, lowest accumulation was seen in KRL 99, MACS 3949 and KRL 3–4 at EC
iw
– 10 dSm
−1
. The mean range of K
+
content was 7.60–9.74% in roots and 4.21–6.61% in shoots under control environment which decreased to 50.77% in roots and 46.05% in shoots under extreme salinity condition of EC
iw
– 10 dSm
−1
. At EC
iw
– 10 dSm
−1
, KRL 99 maintained highest K
+/
Na
+
in both root and shoot followed by KRL 3–4, HI 8737, MACS 3949, HD 4728 in roots and MACS 3949, KRL 3–4, MACS 4020, HD 4758, MACS 3972 and HI 8713 in shoots. The differential response of durum wheat genotypes under salinity particularly for physiological traits, confer their adaptability towards stress environments and exhibit their potential as genetic sources in breeding programs for improving salt stress tolerance.
“…2 A). This decrease in chlorophyll content might be due to reduced activity of ALA synthase enzyme responsible for chlorophyll synthesis or due to increased activity of chlorophyll degrading enzyme, chlorophyllase ( Garg and Singla, 2004 , Singh et al, 2016 ; Mann et al, 2018 ) or the excessive accumulation of Na + in the leaf tissues resulted in an alteration of the chlorophyll pigments, and/or a restriction of its biosynthesis which translates into a chlorosis of leaves ( Yadav et al, 2020 ). Fig.…”
In the era of climate change, decreased precipitation and increased evapo-transpiration hampers the yield of several cereal crops along with the soil salinity and poor ground water resource. Wheat being the moderately tolerant crop face many challenges in the arid and semi-arid regions under irrigated agriculture. In view of this, the study was planned to explore the potential of durum wheat genotypes under salinity on the basis of physiological traits. Experiment was designed as RBD in three replications to evaluate 15 wheat genotypes with moderate saline irrigation (EC
iw
– 6 dS m
−1
) and extreme saline irrigation (EC
iw
– 10 dS m
−1
) along with one set of control (Best available water). Different physiological traits such as water potential (ψ
p
), osmotic potential (ψ
s
), relative water content (RWC), Na
+
and K
+
content were recorded in roots as well as shoots at the reproductive stage whereas photosynthetic rate and chlorophyll content were measured in the flag leaves. A significant variability (p < 0.001) was noted among the genotypes under different stress environments and it was observed that durum genotype HI 8728 and HI 8737 showed less reduction in plant water traits (RWC, ψ
p
and ψ
s
) than the salinity tolerant checks of bread wheat KRL 99 and KRL 3–4. HD 4728 and HI 8708 maintained higher photosynthetic rate as well as higher chlorophyll content under the extreme salinity level of EC
iw
– 10 dSm
−1
. No significant differences were found in root Na
+
in genotypes KRL 99 (3.17
g
), KRL 3–4 (3.34
g
) and HI 8737 (3.41
g
) while in shoots, lowest accumulation was seen in KRL 99, MACS 3949 and KRL 3–4 at EC
iw
– 10 dSm
−1
. The mean range of K
+
content was 7.60–9.74% in roots and 4.21–6.61% in shoots under control environment which decreased to 50.77% in roots and 46.05% in shoots under extreme salinity condition of EC
iw
– 10 dSm
−1
. At EC
iw
– 10 dSm
−1
, KRL 99 maintained highest K
+/
Na
+
in both root and shoot followed by KRL 3–4, HI 8737, MACS 3949, HD 4728 in roots and MACS 3949, KRL 3–4, MACS 4020, HD 4758, MACS 3972 and HI 8713 in shoots. The differential response of durum wheat genotypes under salinity particularly for physiological traits, confer their adaptability towards stress environments and exhibit their potential as genetic sources in breeding programs for improving salt stress tolerance.
“…Chlorophyll is an important molecule in photosynthesis, and plant bioregulators help to increase the quality of chlorophyll by maintaining cellular osmotic reactions ( Burman et al, 2004 ; Seckin et al, 2009 ). The decrease in chlorophyll content in wheat under pathogen and salt stress may be due to increased chlorophyll degradation or decreased activity of chlorophyll biosynthesis enzymes ( Singh et al, 2016 ; Mann et al, 2019 ). Larger decreases in chlorophyll concentration have also been associated with exacerbation of stress symptoms ( Kumar et al, 2018 ).…”
Salinity is abiotic stress that inhibits seed germination and suppresses plant growth and root development in a dose-dependent manner. Fusarium pseudograminearum (Fg) is a plant pathogen that causes wheat crown rot. Chemical control methods against Fg are toxic to the environment and resistance has been observed in wheat crops. Therefore, an alternative approach is needed to manage this devastating disease and the effects of salinity. Our research focused on the mycoparasitic mechanisms of Trichoderma longibrachiatum (TG1) on Fg and the induction of defenses in wheat seedlings under salt and Fg stress at physiological, biochemical and molecular levels. The average inhibition rate of TG1 against Fg was 33.86%, 36.32%, 44.59%, and 46.62%, respectively, in the four NaCl treatments (0, 50, 100, and 150 mM). The mycoparasitic mechanisms of TG1 against Fg were coiling, penetration, and wrapping of Fg hyphae. In response to inoculation of TG1 with Fg, significant upregulation of cell wall degrading enzymes (CWDEs) was observed. The expression of β-1, 6-glucan synthase (PP4), endochitinase precursor (PH-1), and chitinase (chi18-15) increased by 1. 6, 1. 9, and 1.3-fold on day 14 compared with day 3. Wheat seedlings with combined TG1 + Fg treatments under different NaCl stress levels decreased disease index by an average of 51.89%; increased the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity by an average of 38%, 61%, and 24.96%, respectively; and decreased malondialdehyde (MDA) and hydrogen peroxide (H2O2) content by an average of 44.07% and 41.75% respectively, compared with Fg treated seedlings. The combined TG1 + Fg treatment induced the transcription level of plant defense-related genes resulting in an increase in tyrosin-protein kinase (PR2), chitinase class I (CHIA1), and pathogenesis-related protein (PR1-2) by an average of 1.15, 1.35, and 1.37-fold, respectively compared to Fg treatment. However, the expression levels of phenylalanine ammonia-lyase (PAL) increased 3.40-fold under various NaCl stresses. Our results suggest that TG1 enhances wheat seedling growth and controls wheat crown rot disease by strengthening the plant defense system and upregulating the expression of pathogenesis-related genes under both Fg and salt stress.
“…But the application of SA and TU maintained the hydration of cells up to an optimal level, under stress conditions, through accumulation of osmolytes, which sustained water uptake and increased RWC of tissues ( Pooja and Sharma, 2016 ). Decrease in chlorophyll content under water deficit and salinity stress either in pearl millet or in wheat could be attributed to the rate of degradation of chlorophyll or due to reduction in activity of chlorophyll biosynthesis enzymes ( Singh et al, 2016 , Mann et al, 2019 ). Further aggravated stress symptoms have also been observed with greater reductions in chlorophyll concentration ( Kumar et al, 2018 ).…”
Plant growth is often affected with hampered physiological and cellular functioning due to salinity and drought stress. To assess the effectiveness of plant bioregulators (PBRs) in mitigating abiotic stresses, a double spilt plot field study was conducted with three replications at ICAR-CSSRI, research farm, Nain, Panipat. The study comprised of three deficit irrigation regimes viz., 100, 80 and 60% of crop evapo-transpiration (ET
c
) (I
1
, I
2
and I
3
), four levels of irrigation water salinity i.e. 2, 4, 8, 12 dS m
−1
(S
0
, S
1
, S
2
and S
3
) and two PBRs salicylic acid (SA; G
1
) and thiourea (TU; G
2
). Irrigations, as per regimes and salinity, were applied at identified critical stages of wheat and if needed in pearl millet. PBRs were applied as seed priming and foliar sprays at two sensitive stages of respective crops. The trend of plant height, and physiological and biochemical traits was similar under different treatments at both stages, but differed significantly only at reproductive stage. Water deficit caused significant reduction in pearl millet (5.1%) and wheat (6.7%) grain yields. The reduction in grain yield under 8 and 12 dS m
−1
was 12.90 and 22.43% in pearl millet and 7.68 and 32.93% in wheat, respectively compared to 2 dS m
−1
. Application of either SA (G
1
) or TU (G
2
) significantly enhanced plant height and grain yield, but magnitude of the increment was higher with SA in pearl millet and with TU in wheat. Application of SA and TU increased grain yield by 14.42 and 12.98 in pearl millet, and 12.90 and 17.36% in wheat, respectively. The plant height, RWC, TC, MI, LP, proline, Fv/Fm and Na/K ratio significantly reduced by salinity stress in pearl millet and both water and salinity stress in wheat. Application of both PBRs proved beneficial to mitigate adverse effect of water deficit and salt stress by significantly improving physiological traits, biochemical traits and ultimately grain yield in both crops.
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