Mineral accumulation, relative water content and gas exchange are the main physiological regulating mechanisms to cope with salt stress in barley.

Salinity has become a major environmental concern for agricultural lands, leading to decreased crop yields. Hence, plant biology experts aim to genetically improve barley's adaptation to salinity stress by deeply studying the effects of salt stress and the responses of barley to this stress. In this context, our study aims to explore the variation in physiological and biochemical responses of five Tunisian spring barley genotypes to salt stress during the heading phase. Two salinity treatments were induced by using 100 mM NaCl (T1) and 250 mM NaCl (T2) in the irrigation water. Significant phenotypic variations were detected among the genotypes in response to salt stress. Plants exposed to 250 mM of NaCl showed an important decline in all studied physiological parameters namely, gas exchange, ions concentration and relative water content RWC. The observed decreases in concentrations ranged from, approximately, 6.64% to 40.76% for K+, 5.91% to 43.67% for Na+, 14.12% to 52.38% for Ca2+, and 15.22% to 38.48% for Mg2+ across the different genotypes and salt stress levels. However, under salinity conditions, proline and soluble sugars increased for all genotypes with an average increase of 1.6 times in proline concentrations and 1.4 times in soluble sugars concentration. Furthermore, MDA levels rose also for all genotypes, with the biggest rise in Lemsi genotype (114.27% of increase compared to control). Ardhaoui and Rihane showed higher photosynthetic activity compared to the other genotypes across all treatments. The stepwise regression approach identified potassium content, K+/Na+ ratio, relative water content, stomatal conductance and SPAD measurement as predominant traits for thousand kernel weight (R2 = 84.06), suggesting their significant role in alleviating salt stress in barley. Overall, at heading stage, salt accumulation in irrigated soils with saline water significantly influences the growth of barley by influencing gas exchange parameters, mineral composition and water content, in a genotype-dependent manner. These results will serve on elucidating the genetic mechanisms underlying these variations to facilitate targeted improvements in barley's tolerance to salt stress.

Spike developmental stages and ABA role in spikelet primordia abortion contribute to the final yield in barley (Hordeum vulgare L.).

BACKGROUND: Salinity is a significant environmental stress factor limiting crops productivity. Barley (Hordeum vulgare L.) has a natural tolerance to salinity stress, making it an interesting study object in stress biology research. In the present study, for the first time the effect of salinity stress on barley inflorescence developmental stages was investigated. Five spring barley genotypes irrigated with saline water (12.5 ds/m NaCl) were compared to controls treated with normal tap water. We measured abscisic acid (ABA) concentrations in the apical, central and basal sections of the immature inflorescence at green anther (GA) stage. The role of ABA in spikelet primordia development, atrophy and abortion and final yield was evaluated. RESULTS: A time course experiment starting from double ridge until green anther (GA) stages revealed that salinity reduced the length of spike developmental stages in all genotypes causing shortened of the plant life cycle. The shortened plant life cycle negatively affected plant height and number of tillers/plant. Salinity also affected spikelet primordia development. In both control and salinity treated plants apical spikelet abortion started in late awn primordium (AP) stage. However, under salinity treatment, significantly more spikelets were aborted, thus directly affecting plant yield potential. ABA, which plays a role in the spikelet/floret abortion process, was markedly elevated in the base and apex of salt treated spikes correlating with an increased spikelet abortion in these regions. CONCLUSIONS: Overall, salinity treatment reduced all plant and yield-related parameters investigated and turned some of the correlations among them from positive to negative or vice versa. Investigations of ABA role in floral development and phase duration of barley spike showed that, ABA regulates the spikelet/floret abortion process affecting the yield potential under salinity and control conditions.

Fatty acids from Tunisian and Chinese pomegranate (Punica granatum L.) seeds.

Pomegranate seed oil is considered a powerful health-benefiting agent due to its anti-oxidative and anticarcinogenic properties. Lipids from 21 pomegranate cultivars (15 Tunisian and 6 Chinese) were extracted and fatty acids were identified. Total lipids (16% on a dry weight basis) are mainly unsaturated (ca. 88%). Qualitatively, the pomegranate fatty acid composition is identical. Quantitatively, the predominant fatty acid was linolenic acid (44.51-86.14%), followed by linoleic acid (3.57-13.92%), oleic acid (3.03-12.88%), palmitic acid (3.13-11.82%), stearic acid (1.68-15.64%), gadoleic acid (0.50-4.91%), lignoceric acid ( < 2.53%), arachidic acid ( < 1.70%) and myristic acid ( < 0.85%). Statistical methods revealed how Chinese and Tunisian pomegranate fatty acid contents may be affected by the sampling location.

Physico-chemical properties and DPPH-ABTS scavenging activity of some local pomegranate (Punica granatum) ecotypes.

Peels and fresh pomegranate extracts were used in the present study for the determination of the physic-chemical properties and DPPH-ABTS scavenging activities. Total sugars of juice are fructose (ca. 7 g/100 ml) and glucose (ca. 8 g/100 ml). Contents of soluble proteins in juice extracts are about 7 g/l (Bradford assays) and 22% (Kjeldhal assays) from dry pulp. Minerals in peel and juice are respectively 9.43+/-0.93 and 9.46+/-1.05 mg/100 ml for posphorus and 210.86+/-10.70 and 271.94+/-60.59 mg/100 g for potassium. The sodium contents are nearly 7 mg/100 ml in both peel and juice. Highly antioxidant contents in peels were confirmed. Free radical scavenging is about 3.58+/-0.38 microg/ml in peel. The antioxidant capacity value determined by ABTS was 7.364+/-0.403 mM Trolox equivalent antioxidant capacity/100 g dry weight. These findings implied that bio-active compounds from the peel might be potential resources for the development of antioxidant function dietary food.