Iranian Journal of Plant Physiology
Volume:13 Issue: 3, Spring 2023

Saline stress has remained a hot and threatened topic towards population explosion due to shrinkage of agricultural land. Soil salinity being a natural process, is further worsening by anthropogenic activities. The result is decline in plant growth performance and crop productivity. In the present review we have discussed the negative impact of NaCl stress and its action in plants by enhancing ROS formation. Further, their quenching by various physiological and biochemical activities triggered by plants are also presented in the review. Because, sodium chloride represents a wide spread salt, responsible for plant stress. Moreover, increasing antioxidants, compatible solutes and ion homeostasis helps in tolerant as well as sensitive plants to overcome stress. But among different species range of tolerance persists over a specific time and depends upon genotype of species. Furthermore, besides the role of antioxidants and osmolytes, role of various organelles during stress is also discussed. In conclusion, understanding their mechanism at various levels may help to get plants with a range of tolerance at different growth stages, when subject to salt stress. So, increasing crop productivity might replenishes the need of food scarcity over population burst in future.

Evening primrose is one of the herbal biennial medicinal and oilseed plants. Its seed oil is one of the important sources of omega-6 as well as gamma-linolenic acid. Encouraging the plant to flower without winter conditions is important in biennial plants. This experiment aimed to investigate the phenology of evening primrose as affected by vernalization and gibberellic acid. At the beginning of the experiment, the seeds samples were kept in refrigerator conditions (2 to 4 °C) at ‎different periods of 0 to 60 days. To study the influence of GA3 at the end of 60 days, half ‎ of the vernalized seeds were treated with 500 ppm GA3 solution for 24 hours and then were ‎planted. The time of seedling emergence; 4, 6, 8, and 10 leave stages of seedling; stem ‎formation time, flowering time, capsule formation, capsule filling time, side stem production, ‎the time of physiological ripening of the seed, the time capsule browning, and harvest time was ‎recorded. Results showed that, while control plants did not flower, ‎vernalization significantly influenced all of the phenological stages of experimental ‎plants. A combination of vernalization and GA3 significantly affected stem formation ‎time, side stems production time, and capsule filling time. Finally, according to the ‎results, seed priming with 2 to 4 °C moist-chilling for at least 10 days and GA3 in a minimum concentration of 500 ppm guarantee ‎flower formation of seeds of evening primrose with late sowing time in spring.

Almond is one of the most important horticultural crops of the Iran, which has been of interest to Iranian growers for a long time due to its unique characteristics. To select the best cultivars or genotypes of almonds from almond germplasm, an investigation based on frost tolerance (50 genotype and varieties in conditions of the laboratory was conducted using cuttings containing flower buds) in the Horticultural Sciences Researches Institute under laboratory conditions. The tolerance of 50 genotypes to frost in laboratory conditions was investigated in a factorial manner in a completely random design with the first factor of cold at 2 levels (normal temperature or without frost stress and -3°C) and the second factor of genotype at 50 levels with 3 replications. In this research, after screening 50 varieties and genotypes of almonds in relation to tolerance to freezing stress, two varieties and genotypes (Shokofeh and A43D99) were tolerant and two varieties (Peerless and Rabie) were sensitive and 2 varieties and genotypes (Nanpareil and A47MS3 ) intermediates were selected for further investigation, especially in relation to traits related to frost tolerance.It should be noted that the selected genotypes in this research are the result of breeding programs, and with further study and research work, some of these genotypes can be introduced as genotypes resistant to frost stress and used in breeding and cultivation programs.

Seed development and vigor may be influenced by harvest time and height of harvest in onion seeds.Thus,an experiment was conducted to evaluate the effects of different harvest times and height of harvest in enzymatic activity and biochemical changes of seeds in two growth seasons(2014-2015) at Research Farm of the Seed and Plant Institute,Karaj,Iran.The experimental design was a factorial in a randomized complete block with three replications. Four times of harvest (T1(moisture content:60%), T2(moisture content:50%), T3(moisture content:39%), and T4(moisture content:11%)) and four harvest height (0,10,20and30cm bottom of inflorescence) were randomized to the plots. Seeds were harvested in 10 days intervals at four stages during development and maturity. The results showed in both of studied years the maximum catalase(1.847 OD/mg protein min-1) and peroxidase activity(3.852 OD/mg protein min-1) and also the minimum MDA content(0.068 nm g FW) were achieved in 3rd harvest time and 20cm height of harvest. In agreement with the achieved result about enzymatic activity, the maximum 1000seed weigh (4.440g) was observed in the second year and third harvest with 20cm height of harvest. Maximum seed vigor as measured by the electrical conductivity of seed leachate(58.70 μs/cm/g) was obtained at second harvest time with 20cm height of harvest. In this study, earlier harvests due to immaturity and later harvests because of aging reduced seed vigor of onion. The best treatment for achieving suitable seeds was third harvest time and 20cm height of harvest.Also, biochemical traits were helpful in determining the suitable time of harvesting in onion seeds.

Basil (Ocimum basilicum L.) is one of the valuable medicinal plants. Negative effects of NaCl stress on plants have been reported and silicon may alleviate these negative effects through promoting antioxidant system. This study was conducted to investigate the effects of silicon as elicitor and NaCl as salinity stress on some morphological, biochemical, and antioxidant parameters in basil plant. The plants were pretreated with silicon (0, 0.5, and 1.50 mM) and submitted to NaCl stress (0, 50 and 100 mM). Results showed that NaCl stress decreased dry and fresh weight of shoot and root, cholorophyll and carbohydrate content, but carotenoid, hydrogen peroxide (H2O2) content, superoxide dismutase (SOD) and catalase (CAT) activity increased (p<0.05). Silicon also increased dry and fresh weight of shoot and root, carotenoid, chlorophyll and carbohydrate content, CAT and SOD activity but H2O2 content decreased (p<0.05). Based on these results, silicon especially 1.50 mM concentration is recommended for protection of basil under NaCl stress.

Alstroemeria (Alstroemeria sp.) is a permanent herbaceous plant species. Fast yellowing of Alstroemeria (Alstroemeria sp.) leaves after harvest and before petal shedding is the main factor limiting their vase life. This research investigated the effect of thyme essential oil (0, 50, 100, and 200 mg/L) and ethanol (0, 10, 20, and 40 mg/L) on retarding the senescence of cut alstroemeria flowers in a factorial experiment. Various quantitative and qualitative traits particularly vase life, flower opening index, water uptake, fresh weight loss, dry weight percentage, and vase solution and stem-end bacteria population were measured. Thyme essential oil at a concentration of 200 mg/L without ethanol application was most influential on vase life, reduction of bacteria population, and water uptake and exhibited almost acceptable dry weight and flower opening rate. Overall, it is concluded that the suitable application of thyme and ethanol at proper rates is effective in extending the vase life of alstroemeria.

In the present study, the effect of urea fertilizer under pot and greenhouse cultivation on growth rate, total content of leaf terpenoids and bioactive compounds detectable by GC-MS was investigated in American agave leaf extract. Urea 46% fertilizer, with two concentrations of 5 and 10 g / l was used for irrigation, in 8-leaf stage and their effects were compared with plants irrigated with no fertilizer as control in a randomized complete block design. Addition of urea fertilizer with both concentrations increased the fresh and dry weight of leaves and roots. Urea fertilizer had no significant effect on leaf terpenoid content, but in terms of leaf extract analysis by GC-MS, had a positive effect on increasing the content of methyl palmitate and methyl stearate, which are valuable medicinal compounds with antimicrobial, anti-inflammatory, anti-cancer, and antioxidant properties. Utilization of urea fertilizer, doubled the percentage of these compounds in leaf extract. However, urea fertilizer reduced the content of bis(2-ethylhexyl) phthalate, which has also medicinal properties comparable to the two above mentioned compounds. The positive effect of urea fertilizer on a significant increase in octadecane and methyl palmitate (about twice) with usability as a biofuel is another important result of the present work.

Among plant growth regulators, Polyamines (PA) have a major role in diverse plant physiological responses throughout vegetative to reproductive phase and senescence. The present study was conducted to study the impact of polyamine on different physiological and biochemical aspects of hydroponic grown rose (cv. 'Dulce Vita') plants. Putrescine (Put) (at 1, 2, 3 mM), Spermidine (Spd) (at 0.5, 1, 1.5 mM) and Spermine (Spm) (at 1, 2, 4 mM) were sprayed on rose plants during growth and subsequently, different aspects of vegetative growth, flower quality, mineral uptake and plant response to some biochemical responses were studied. Foliar application of Spd at 1.5 mM concentration caused the highest flower stem length and flower bud size. Vase life was affected by PA application, in which, Spd had the greatest beneficial outcome. Absorption and accumulation of the studied macro- and micro-nutrient content in leaves were also influenced by PA treatment. ACC synthase and chlorophyllase activity in leaves of cut flowers harvested from PA treated plants was affected, in which 4mM Spm treatment lead to the least. Although malondialdehyde production in flower stem leaves of ‘Dolce Vita’ rose increased during postharvest life as flowers aged, but the increment was retarded by PA application.

The relationship between relative expression of three Si transporters (Lsi1, Lsi2 and Lsi6) genes and Si contents, in four different segments of maize seedling: basal, apical parts of seminal roots, leaf sheaths, and blades under Si concentrations (0, 2 and 10 mM) was investigated. The results indicated that under the control conditions, Si content in aerial parts and roots of seedlings were identical but under 2 and 10 mM Si concentrations, its content in the aerial parts was higher than the roots. Silicon uptake by maize seedlings was not proportional to the increase of its supply. Unexpectedly, the Si content of maize seedlings did not increase when the Si supply increased to 10. The results also showed that under normal conditions, relative expression of ZmLsi1 and ZmLsi2 in shoots of maize seedlings was significantly higher than roots, while ZmLsi6 was mainly expressed in leaf sheaths. Application of Si significantly increased all three silicon transporter expressions. Among these transporters, the response of Lsi2 was discriminative to the external Si concentration such that under 10 mM Si, the expression of Lsi2 was more noticeable. The results suggested that Lsi2 may have a role in efflux of Si in maize under high concentration of external Si.