Nanopotassium, Nanosilicon, and Biochar Applications Improve Potato Salt Tolerance by Modulating Photosynthesis, Water Status, and Biochemical Constituents

Salinity is one of the main environmental stresses, and it affects potato growth and productivity in arid and semiarid regions by disturbing physiological process, such as the photosynthesis rate, the absorption of essential nutrients and water, plant hormonal functions, and vital metabolic pathways. Few studies are available on the application of combined nanomaterials to mitigate salinity stress on potato plants (Solanum tuberosum L. cv. Diamont). In order to assess the effects of the sole or combined application of silicon (Si) and potassium (K) nanoparticles and biochar (Bc) on the agro-physiological properties and biochemical constituents of potato plants grown in saline soil, two open-field experiments were executed on a randomized complete block design (RCBD), with five replicates. The results show that the biochar application and nanoelements (n-K and n-Si) significantly improved the plant heights, the fresh and dry plant biomasses, the numbers of stems/plant, the leaf relative water content, the leaf chlorophyll content, the photosynthetic rate (Pn), the leaf stomatal conductance (Gc), and the tuber yields, compared to the untreated potato plants (CT). Moreover, the nanoelements and biochar improved the content of the endogenous elements of the plant tissues (N, P, K, Mg, Fe, Mn, and B), the leaf proline, and the leaf gibberellic acid (GA3), in addition to reducing the leaf abscisic acid content (ABA), the activity of catalase (CAT), and the peroxidase (POD) and polyphenol oxidase (PPO) in the leaves of salt-stressed potato plants. The combined treatment achieved maximum plant growth parameters, physiological parameters, and nutrient concentrations, and minimum transpiration rates (Tr), leaf abscisic acid content (ABA), and activities of the leaf antioxidant enzymes (CAT, POD, and PPO). Furthermore, the combined treatment also showed the highest tuber yield and tuber quality, including the contents of carbohydrates, proteins, and the endogenous nutrients of the tuber tissues (N, P, and K), and the lowest starch content. Moreover, Pearson’s correlation showed that the plant growth and the tuber yields of potato plants significantly and positively correlated with the photosynthesis rate, the internal CO2 concentration, the relative water content, the proline, the chlorophyll content, and the GA3, and that they were negatively correlated with the leaf Na content, PPO, CAT, ABA, MDA, and Tr. It might be concluded that nanoelement (n-K and n-Si) and biochar applications are a promising method to enhance the plant growth and crop productivity of potato plants grown under salinity conditions.

Features of the economical yield formation of apple plants under non-root nutrition in the Southern Russia organic plantings

In this work are determined the prospects of application new complex fertilizer chelate “Naliv” for apple plants non-root nutrition in connection with optimization of economic yield formation in the Southern Russia organic plantations. The field experiment was carried out in the organic apple tree plantations of the educational farm "Kuban" of the KubSAU, planted in 2002. The experimental field soil is leached chernozem. Trees foliar dressing was carried out with organic fertilizer 40-45 days before harvest. Control variant was trees treatment with water. The accumulation of glucose and fructose, associated with a significant (1.4 times) increase in their average weight, activate in ripening fruits under fertilizer application as a late-summer foliar dressing. Equally, the economic yield increases by 14% compared to control value. The fertilizer application accelerates the generative apple bud dormancy beginning and, accordingly, dormancy ending. An increase in the abscisic acid content in generative buds in late autumn, initiated by the fertilizer action, plays a certain role in achieving this effect. Equally, the plants resistance to low temperatures of the spring increases. Thus, favorable conditions are created to improve the commercial quality of fruits and optimize fruiting in adjacent years under fertilizers application in organic apple plantations.

Foliar nano-fertilization enhances fruit growth, maturity and biochemical responses of date palm

The experiment was conducted in the Abi Al-Khaseeb orchard, Basrah, Iraq during the 2019 season, on date palm (Hillawi cv.). The effect of foliar nano-fertilizer on the response of the growth and fruit ripening rate was amid. Adding nano-fertilizer to the annual date palm fertilization program improved growth and increased production. A comparison of foliar NPK (1, 2 g L-1) as nano-fertilizer and traditional fertilizer, and combined, was applied. The results revealed that the treatment of foliar traditional and nano-fertilizers together increased the weight of fruit and bunches, water content, indoleacetic acid, and gibberellic acid relative to other treatments. Nano-fertilizers (1g L -1) led to an increase in fruit ripening rate, dry mass, and total soluble solids, activity of the enzymes peroxidase, and superoxide dismutase, and abscisic acid content. The leaflet protein expression shows that the appearance of protein bands 1 to 5 and 6 was up-regulated by control and traditional fertilizer. Whereas the protein bands 6 and 7 were down-controlled under nano-fertilizer. Hierarchical cluster analysis of proteins in the leaf in response to traditional and nano-fertilizer showed two distinct clusters. The use of nano-fertilizer individually leads to the acceleration of fruit ripening. while the production fruit that is increased using foliar nano-fertilizer with traditional fertilizer.

Changes in abscisic acid content during and after drought are related to carbohydrate mobilization and hydraulic recovery in poplar stems

Drought compromises plant's ability to replace transpired water vapor with water absorbed from the soil, leading to extensive xylem dysfunction and causing plant desiccation and death. Short-term plant responses to drought rely on stomatal closure, and on the plant's ability to recover hydraulic functioning after drought relief. We hypothesize a key role for abscisic acid (ABA) not only in the control of stomatal aperture, but also in hydraulic recovery. Young plants of Populus nigra L. were used to investigate possible relationships among ABA, non-structural carbohydrates (NSC) and xylem hydraulic function under drought and after re-watering. In Populus nigra L. plants subjected to drought, water transport efficiency and hydraulic recovery after re-watering were monitored by measuring the percentage loss of hydraulic conductivity (PLC) and stem specific hydraulic conductivity (Kstem). In the same plants ABA and NSC were quantified in wood and bark. Drought severely reduced stomatal conductance (gL) and markedly increased the PLC. Leaf and stem water potential, and stem hydraulic efficiency fully recovered within 24 h after re-watering, but gL values remained low. After re-watering, we found significant correlations between changes in ABA content and hexoses concentration both in wood and bark. Our findings suggest a role for ABA in the regulation of stem carbohydrate metabolism and starch mobilization upon drought relief, possibly promoting the restoration of xylem transport capacity.