Effects of foliar application of humic acid extracts and indole acetic acid on important growth indices of canola (Brassica napus L.).

Vermicompost (VC) is a rich source of HA that improves plant growth and yield indices such as fresh and dry weights, plant height, stem diameter, leaf area, and chlorophyll index value. In this study, the effect of foliar application of HA extracted from different types of VC enriched with bacteria and/or fertilizers, commercial HA (CHA) and indole acetic acid (IAA) on the growth characteristics of canola (Brassica napus) in greenhouse conditions were compared. According to the results, the foliar application of HA extracted from VC had complete superiority over CHA and IAA in most traits except for the leaf number. Furthermore, the highest level of foliar application of HA (600 mg L-1) enriched with Azotobacter chroococcum (21Az) + Pseudomonas fluorescens (Ps 59) (HA-AS) generated the highest height, diameter, leaf area, and chlorophyll index value. Also, the highest stomatal conductance and photosynthesis rate were observed with the application of 600 mg L-1 HA extracted from VC enriched with nitrogen, sulfur, and phosphorus (HA-NSP) compared to the other treatments. Besides, dry and fresh weights and seed yield under HA-NSP and HA-AS treatments were at their highest rate. Among the extracted HAs, the one extracted from the nitrogen enriched VC had the lowest efficiency. Based on the present study, the HA extracted from VC enriched with Azotobacter, Pseudomonas and NSP is recommended to increase canola growth and production.

Biochemical and molecular responses of Rosa damascena mill. cv. Kashan to salicylic acid under salinity stress.

BACKGROUND: Today, salinity stress is one of the most important abiotic stresses in the world, because it causes damage to many agricultural products and reduces their yields. Oxidative stress causes tissue damages in plants, which occurs with the production of reactive oxygen species (ROS) when plants are exposed to environmental stresses such as salinity. Today, it is recommended to use compounds that increase the resistance of plants to environmental stresses and improve plant metabolic activities. Salicylic acid (SA), as an intracellular and extracellular regulator of the plant response, is known as one of these effective compounds. Damask rose (Rosa damascena Mill.) is a medicinal plant from the Rosaceae, and its essential oils and aromatic compounds are used widely in the cosmetic and food industries in the world. Therefore, considering the importance of this plant from both medicinal and ornamental aspects, for the first time, we investigated one of the native cultivars of Iran (Kashan). Since one of the most important problems in Damask rose cultivation is the occurrence of salinity stress, for the first time, we investigated the interaction of several levels of NaCl salinity (0, 4, 8, and 12 ds m- 1) with SA (0, 0.5, 1, and 2 mM) as a stress reducer. RESULTS: Since salinity stress reduces plant growth and yield, in this experiment, the results showed that the increase in NaCl concentration caused a gradual decrease in photosynthetic and morphological parameters and an increase in ion leakage. Also, increasing the level of salinity stress up to 12 ds m- 1 affected the amount of chlorophyll, root length and leaf total area, all of which reduced significantly compared to plants under no stress. However, many studies have highlighted the application of compounds that reduce the negative effects of stress and increase plant resistance and tolerance against stresses. In this study, the application of SA even at low concentration (0.5 mM) could neutralize the negative effects of salinity stress in the Rosa damascena. In this regard, the results showed that salinity increases the activity of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) and the concentration of proline, protein and glycine betaine (GB). Overexpression of antioxidant genes (Ascorbate Peroxidase (APX), CAT, Peroxidase (POD), Fe-SOD and Cu-SOD) showed an important role in salt tolerance in Damascus rose. In addition, 0.5 mm SA increased the activity of enzymatic and non-enzymatic systems and increased salinity tolerance. CONCLUSIONS: The change in weather conditions due to global warming and increased dryness contributes to the salinization of the earth's surface soils. Therefore, it is of particular importance to measure the threshold of tolerance of roses to salinity stress and the effect of stress-reducing substances in plants. In this context, SA has various roles such as increasing the content of pigments, preventing ethylene biosynthesis, increasing growth, and activating genes involved in stress, which modifies the negative effects of salinity stress. Also, according to the results of this research, even in the concentration of low values, positive results can be obtained from SA, so it can be recommended as a relatively cheap and available material to improve production in saline lands.

Effect of Different Enriched Vermicomposts, Humic Acid Extract and Indole-3-Acetic Acid Amendments on the Growth of Brassica napus.

Humic acid (HA) is a specific and stable component of humus materials that behaves similarly to growth stimulants, esp. auxin hormones, contributing to improving growth indices and performance of plants. As a rich source of HA, vermicompost (VC) is also a plant growth stimulating bio-fertilizer that can enhance growth indices and performance in plants. The purpose of the present study is to compare the influence of VC enriched with bacterial and/or fertilizer, commercial humic acid (CHA) extract, and indole-3-acetic acid (IAA) on improving growth characteristics and performance of rapeseed under greenhouse conditions. The results showed the complete superiority of VC over the CHA and IAA (approximately 8% increase in the dry weights of root and aerial organ and nearly three times increase in seed weight). The highest values of these indices were obtained with VC enriched with Nitrogen, Sulfur, and Phosphorus, Azotobacter chroococcum and Pseudomonas fluorescens; the lowest value was obtained with VC enriched with urea. Additionally, the application of 3% VC and the control involved the highest and lowest values in all traits, respectively. The SPAD (chlorophyll index) value and stem diameter were not significantly affected by different application levels of VC. Overall, the applications of IAA and the CHA were not found to be suitable and therefore not recommended.

Investigation of photosynthetic effects, carbohydrate and starch content in cress (Lepidium sativum) under the influence of blue and red spectrum.

In order to study the effect of the quality of different LED light spectra (90%R+10%B, 60%R+40%B and control) on photosynthetic parameters (photosynthetic rate (PG), Fv/Fm and ΦPSII) of stomatal conductance, transpiration rate, carbohydrate, starch and chlorophyll index on cress (Lepidium Sativum), a pot experiment was conducted under the greenhouse cultivation-without-soil (hydroponics) condition in the form of split plot based on a completely randomized design with 6 replications. The results showed that the combined application of blue and red light spectra with different percentages had a positive and significant effect on all traits. The highest amounts of each of the photosynthetic parameters in the 60R:40B treatment were 12.4, 0.87, and 0.92 (µmol CO2 m-2 s-1), respectively, and the lowest amounts (19.6, 0.39, and 0.44 (µmol CO2 m-2 s-1)) were observed in the control treatment. The highest amounts of stomatal conductance, carbohydrate and starch of leaves which were 0.3 (cm.s-2), 5.59 and 6.44 (mg.g-1 FW), respectively, were observed in the 90R: 10B treatment as a result of red light increase. Furthermore, in the control treatment, the light source of which was the natural sunlight, the lowest amounts of 0.11 (cm.s-2), 1.98 and 1.09 (mg.g-1 FW) were observed. The highest transpiration rate (25/83 (mol.m-2.s-1)) was observed in the 60R: 40B treatment which had experienced a significant increase compared to the control light (sunlight) treatment and the lowest transpiration rate (5.5 (mol.m-2.s-1)) was in the control (sunlight) treatment. The chlorophyll index in the 60R: 40B treatment was 41.18, which showed a significant difference from the other treatments (p ≤ 0.01) and the lowest amount of 25.5 was detected in the control treatment. As a result, it can be stated that the use of blue and red light spectra in combination with different percentages can have various positive effects on the growth and development of plants; therefore, the existence of both types of spectra is suggested. This technology means that a particular combination of LED light spectra can be useful for a variety of commercial greenhouse products, especially the valuable ones.

The growth and development of cress (Lepidium sativum) affected by blue and red light.

Today, the use of light emitting diodes (LEDs) are rapidly increasing in horticulture industry as a result of technological advancements. Lighting systems play an important role in the commercial greenhouse productions. As an artificial source of light, LED lamps can contribute to the better and faster growth of horticulture products such as vegetables grown in greenhouses. In this study, the effects of red and blue light spectrums were implemented and performed as a pot experiment under the cultivation-without-soil condition in greenhouse based on a completely random plan with 3 lighting treatments including natural light (control), 60% red light +40% blue light (60R:40B), and 90% red light +10% blue light (90R:10B), repeated 3 times. The results showed that the application of blue and red lights affected the fresh and dry weights of cress as well as its biomass, demonstrating a considerable increase compared to the plants grown under natural sunlight condition. In this regard, the fresh weight of the plant under the 60R:40B treatment had 57.11% increase compared to the natural light treatment. Compared to the control sample, the dry weight had 26.06% increase under 90R:10B treatment. The highest extent of biomass was observed under the 60R:40B lighting treatment with a value of 1.51 (g per kg dry weight of the plant), which was a 68.87% increase compared to the natural light treatment. Under the 60R:40B treatment, cress had its highest length at 19.76 cm. Under the similar treatment, the cress leaf had a total area of 56.78 cm2 which was the largest. The stem diameter and the number of leaves under the 60R:40B treatment had their highest values at 3.28 mm and 8.16, respectively. Accordingly, a growing trend was observed with 56.7 and 61.27% increase compared to the control treatment. Furthermore, the biochemical traits of cress, the amount of a, b and total chlorophyll, the amount of anthocyanin and phenolic contents under the application of red and blue light were at their highest values compared to the control treatment. The highest amount of chlorophyll was observed under 60R:40B treatment as 15.09 mg g-1 FW leaf. Moreover, the phenolic contents and the amount of anthocyanin were of significant difference at 1% level of likelihood compared to the control treatment. Therefore, the vegetative growth of cress was substantially affected by red and blue lights, resulting in the enhancement of the plant's biochemical features compared to control condition via adjusting the lighting quality and impacts of each red and blue light spectrum on their specific receptors. As a result, the presence of both lighting spectrums is essential for expanding and increasing the quality of the plant. At the large scale, this technology is capable of improving the commercial greenhouse production performance while helping farmers achieve maximum products. This particular combination of lights is one of the beneficial features of LED lighting systems intended for different types of commercial greenhouse productions, especially the valuable greenhouse products.