Mutual physiological genetic mechanism of plant high water use efficiency and nutrition use efficiency

Water deficiency and lower fertilizer utilization efficiency are major constraints of productivity and yield stability. Improvements of crop water use efficiency (WUE) and nutrient use efficiency (NUE) is becoming an important objective in crop breeding. With the introduction of new physiological and biological approaches, we can better understand the mutual genetics mechanism of high use efficiency of water and nutrient. Much work has been done in past decades mainly including the interactions between different fertilizers and water influences on root characteristics and crop growth. Fertilizer quantity and form were regulated in order to improve crop WUE. The crop WUE and NUE shared the same increment tendency during evolution process; some genes associated with WUE and NUE have been precisely located and marked on the same chromosomes, some genes related to WUE and NUE have been cloned and transferred into wheat and rice and other plants, they can enhance water and nutrient use efficiency. The proteins transporting nutrient and water were identified such as some water channel proteins. The advance on the mechanism of higher water and nutrient use efficiency in crop was reviewed in this article, and it could provide some useful information for further research on WUE and NUE in crop.     

Osmotic regulation of 10 wheat (Triticum aestivum L.) genotypes at soil water deficits

Drought is a worldwide problem, seriously influencing plant (crop) productivity. Wheat is a stable food for 35% of the world population, moreover about 60% of land area on the globe belongs to arid and semi-arid zone. Wheat drought resistance is a multi-gene-controlling quantitative character and wheat final production in field is realized mainly by physiological regulation under the condition of multi-environmental factor interaction. Exploring drought resistance physiological mechanisms for different wheat genotypes is of importance to finding new drought resistance gene resources and conventional breeding and the basis for wheat drought resistance biotechnological breeding and platform. Osmotic adjustment regulation is the main component for physiological machinery of wheat drought resistance. By pot-cultivating experiments, investigation of osmotic adjustment comparison for 10 wheat genotypes at soil water deficits (75% FC, 55% FC, 45% FC, respectively), was conducted. The main results were as followed: (1) K⁺ content in 10 wheat genotypes at three levels of soil water stress and at the same soil water deficit was very different. Five of these 10 wheat genotypes had higher K K⁺ content under the condition of 75% FC. (2) Five of these 10 wheat genotypes possessed greater soluble sugar content at 55% FC soil water level. (3) Proline (Pro) content in five wheat genotypes was higher at 75% FC. (4) Five of these 10 wheat genotypes had lower malondialdehyde (MDA) content at 45% FC at seedling stage. Osmotic adjustment of wheat different genotypes was discussed in terms of different content of osmotic solutes.     

Investigation on dynamic changes of photosynthetic characteristics of 10 wheat (Triticum aestivum L.) genotypes during two vegetative-growth stages at water deficits

Drought is a worldwide problem, seriously influencing plant (crop) productivity. Wheat is a stable food for 35% of the world population, and moreover, about 60% of land area on the globe belongs to arid and semiarid zone. Wheat drought resistance is a multi-gene controlling quantitative character and wheat final production in field is realized mainly by physiological regulation under the condition of multi-environmental factor interaction. Exploring drought resistance physiological mechanisms for different wheat genotypes is of importance to finding new drought resistance gene resources and conventional breeding, and the basis for wheat drought resistance biotechnological breeding and platform. Photosynthesis is the main component for physiological machinery of wheat assimilates conversion and wheat production. Investigation on photosynthetic characteristics of different wheat genotypes at soil water deficits also has other implications for refine physiological regulation of photosynthesis in fields and field management of crops in arid and semiarid areas. By pot-cultivating experiments, investigation of photosynthesis for 10 wheat genotypes at seedling stage and tillering stage at soil water deficits (75%FC, 55%FC and 45%FC, respectively) was conducted. The main results were as followed: developmental stages influenced wheat photosynthesis greatly and tillering stage played more roles; there were significant difference in the main photosynthetic parameters, photosynthesis rate (Photo), stomatal conductance (Cond) and transpiration rate (Tr), among 10 wheat genotypes; general photosynthesis and drought resistance in different wheat genotypes was related much to their domesticated origin soil water environment and selected generations and there was a photosynthetic threshold effect in terms of different wheat genotypes at soil water deficits.     

Regulation of photosynthesis, fluorescence, stomatal conductance and water-use efficiency of cowpea (Vigna unguiculata [L.] Walp.) under drought

Drought is the major abiotic stress factor that causes extensive losses to agriculture production worldwide. The objective of this study was to evaluate the dynamics of photosynthesis and water-use efficiency parameters in 15 cowpea genotypes under well-watered and drought condition. Photosynthesis (A) and chlorophyll fluorescence (Fv'/Fm') declined linearly with decreasing soil water content whereas intrinsic water-use efficiency (WUE) increased under drought stress, suggesting stomatal regulation was a major limitation to photosynthesis. However, under increasing drought conditions, increase in ratio of intercellular CO(2) to ambient CO(2) concentrations along with reduced WUE showed the role of non-stomatal limitation of photosynthesis. The resistant nature of Fv'/Fm' and electron transport rate under drought appeared to be important mechanisms for photoinhibition protection under drought stress. Oxidative stress was apparent due to drought-induced reduction in total chlorophyll and carotenoid which was accompanied with increased leaf wax contents. The accumulation of proline appeared to be in response of drought injury rather than a drought tolerance mechanism. A clear separation based on the genotypes site of origin among the genotypes for drought tolerance could not be established when analyzed using principal component analysis. The identified genotypes and physiological traits from this study may be useful for genetic engineering and breeding programs integrating drought adaptation in cowpea.     

Investigation on water consumption characteristics and water use efficiency of poplar under soil water deficits on the Loess Plateau

The water consumption characteristics and water use efficiency (WUE) of poplar (Populus simonii) were investigated under the condition of three different soil water regimes, which were 70%, 55% and 40% of field capacity (FC), respectively. The results showed that water potential, water content, photosynthetic rate, WUE of leaves, and plant growth rate decreased significantly with reduction in soil water content. At the level of adequate and medium soil water content, rapid growth and biomass accumulation in poplar occurred during May and June, whereas this phenomenon occurred only during May under severe soil drought condition. Total water consumption and biomass growth were the greatest under adequate soil water condition, decreased under medium soil drought condition, and lowest under severe soil drought condition. Total WUE was the highest under medium soil water condition and lowest under severe soil condition. Changing patterns of water consumption for daily rate, every 10-day rate, and month rate were quite different under these three soil water regimes. For all these three treatments, the highest monthly water consumption rate occurred during July and June. The highest water consumption over a 10-day period was during in the second 10 days of July, the first 10 days of July, and the last 10 days of June for these three treatments, respectively. The day for the highest water consumption in the medium and severe drought treatments occurred 1 or 2 months earlier than the adequate soil water treatment. The daily time for the greatest water consumption was different throughout the life span of poplar under these soil water levels. According to these results, we concluded that poplar did not have the characteristics of drought-resistance plants, and we do not recommend that this tree species be planted over a wider range of the Loess Plateau in China.     

Relationship between water use efficiency (WUE) and production of different wheat genotypes at soil water deficit

Through 2-year field experiments, 7 wheat genotypes were better in their field yield. These 7 wheat genotypes and other 3 wheat species, which are being popularized on a large scale in different locations of China, were selected as experimental materials for the sake of measuring their difference in WUE and production and comparing their relationship at soil water deficits, future more, providing better drought resistance lines and theoretical guide for wheat production and practices and exploring anti-drought physiological mechanisms of different wheat genotypes. Under the condition of 3 soil–water–stress treatments (75% field capacity (FC), 55% FC, 45% FC, named level 1, level 2 and level 3, respectively), pot experiments for them were conducted and the related data were collected from their life circle. The main results were as followed: (1) according to the selected soil stress levels, water use efficiency (WUE) of 10 different wheat genotypes was divided into two groups (A and B); group A included genotypes 2, 3, 4, 5, 6, 7, 8, whose WUE decreased basically from level 1 to level 3 and reached individual peak of WUE at level 1; Group 2 included genotypes 1, 9, 10, whose WUE reached their individual peak at level 2; (2) based on total water consumption through all life circle, genotypes 1, 4, 8, 9 had lower water consumption (TWC) at level 1, genotypes 2, 3, 5, 6, 7 lower TWC at level 2, genotype 10 lower TWC at level 3; (3) at level 1, genotypes 2, 3, 4, 5, 6, 7, 8 had higher grain weight of single spike (GWSS), genotypes 1, 9, 10 better GWSS at level 2, which was in good line with individual WUE of different wheat genotypes; (4) by analyzing the indexes related to examining cultivars, it was found that genotypes 1, 2, 3, 4, 5, 6, 9, 10 had longer plant length (PL), spike length (SL), bigger grain number (GN) except genotypes 7 and 8 at level 1, RL was in better line with genotypes 1, 2, 3, 8, 9, 10, but not in the other genotypes at level 1.     

Investigation on the relationship between leaf water use efficiency and physio-biochemical traits of winter wheat under rained condition

Different statistical methods and path analysis were used to study the relationship between leaf water use efficiency (WUE) and physio-biochemical traits for 19 wheat genotypes, including photosynthesis rate (P_n), stomatal conductance (g_s), transpiration rate (T_r), intercellular concentration of carbon oxide (C_i), leaf water potential (Ψ_w), leaf temperature, wax content, leaf relative water content (RWC), rate of water loss from excised-leaf (RWL), peroxidase (POD) and superoxide dismutase (SOD) activities. The results showed that photosynthesis rate, stomatal conductance and transpiration rate were the most important leaf WUE variables under rainfed conditions. Based on the results of five statistical analyses, it is reasonable to assume that high leaf WUE wheat under the rained could be obtained by selecting breeding materials with high photosynthesis rate, low transpiration rate and stomatal conductance.     

A Review on Current Status of Biochar Uses in Agriculture

In a time when climate change increases desertification and drought globally, novel and effective solutions are required in order to continue food production for the world’s increasing population. Synthetic fertilizers have been long used to improve the productivity of agricultural soils, part of which leaches into the environment and emits greenhouse gasses (GHG). Some fundamental challenges within agricultural practices include the improvement of water retention and microbiota in soils, as well as boosting the efficiency of fertilizers. Biochar is a nutrient rich material produced from biomass, gaining attention for soil amendment purposes, improving crop yields as well as for carbon sequestration. This study summarizes the potential benefits of biochar applications, placing emphasis on its application in the agricultural sector. It seems biochar used for soil amendment improves nutrient density of soils, water holding capacity, reduces fertilizer requirements, enhances soil microbiota, and increases crop yields. Additionally, biochar usage has many environmental benefits, economic benefits, and a potential role to play in carbon credit systems. Biochar (also known as biocarbon) may hold the answer to these fundamental requirements.     

磷素营养对植物抗旱性的影响

综述了近年来磷素营养与植物抗旱性关系的研究进展，指出磷素营养主要通过水分调节、渗透调节、光合调节和根冠生长等一系列生理生长机制来增强植物的代谢活性，提高植物抗旱性，植物对磷的利用效率与抗旱性也有着密切的关系。     

Synthesis and Properties of Renewable Environment‐Friendly Epoxy Resins for Surface Coatings

Sunflower, soybean, and linseed oils are renewable resources that can be readily epoxidized. Epoxidation of these oils has the potential for use as an environmentally friendly, reactive material in pigmented formulation, designed for use as functional coatings. This study concern the synthesis of phthalimide modified epoxy compounds through reacting N‐(2‐hydroxyethyl) phthalimide (HEP) with epoxidized sunflower, soybean and linseed oils. The resulting compounds possessed both oxirane ring and phthalimide group. Incorporation of phthalimide group into epoxy resins provided cyclic imide structure and high cross‐linking density to the stoved resins, to achieve good mechanical characteristics and high chemical resistance to these resins. The films of phthalimide sunflower, soybean and linseed‐based epoxy resins were found to be similar with respect to resistance to water, alkali, acids, and solvents as well as gloss%, adhesion, impact, hardness, bending, and flexibility.     

Salicylic Acid Stimulates Defense Systems in Allium hirtifolium Grown under Water Deficit Stress

Nowadays, the use of the growth regulator salicylic acid for improving a plant’s resistance to environmental stresses such as drought is increasing. The present study investigated the effect of salicylic acid on the physiological traits, antioxidant enzymes, yield, and quality of Allium hirtifolium (shallots) under drought conditions for three years (2016–2017, 2017–2018, and 2018–2019). The experiment was conducted as a split-plot based on a randomized complete block design with four repeats. Irrigation as the main factor in four levels of 100% (full irrigation), 75% and 50% of the plant water requirements with non-irrigation (dryland), and salicylic acid as the sub-factor in four levels of 0, 0.75, and 1 mmol, were the studied factors in this research. The combined analysis of three-year data showed that drought reduced leaf relative water content (RWC), membrane stability index (MSI), chlorophyll content, onion yield, and increased activity of antioxidant enzymes, proline content, tang, and allicin of shallots. Shallot spraying with salicylic acid improved leaf RWC, MSI, chlorophyll content, and onion yield. The highest yield of onion (1427 gr m⁻²) belonged to full irrigation and foliar application of 1 mmol salicylic acid. The lowest yield (419.8 gr m⁻²) belonged to plats with non-irrigation and non-application of salicylic acid. By improving the effective physiological traits in resistance to water deficit, salicylic acid adjusted the effects of water deficit on the yield of shallots. Foliar application of 1 mmol salicylic acid in dryland and irrigation of 50% of the plant water requirement increased onion yield by 15.12% and 29.39%, respectively, compared to the control treatment without salicylic acid.     

Potential effects of biochar application on mitigating the drought stress implications on wheat (Triticum aestivum L.) under various growth stages

Drought is the main abiotic stress that severely reduces wheat yield across the globe. To cope up this situation, use of organic amendments is the best option. Biochar is an organic soil amendment that is used to improve soil carbon, organic contents, improve water holding capacity of soil, enhance soil fertility and maintain desired soil. Present study was carried out under semi-arid climatic conditions to mitigate the adverse effects of drought at critical wheat growth stages i.e., tillering (DTS), flowering (DFS) and grain filling stage (DGFS) by using three biochar treatments viz. B₀ = Control, B₁ = 27.88 g kg⁻¹ and B₂ = 37.18 g kg⁻¹. Results revealed that drought stress negatively affected the growth and yield attributes of wheat at all critical growth stages, while, grain filling stage was found the most sensitive stage resulted severe yield reduction. However, biochar application significantly mitigated the detrimental effects of drought by improving number of fertile tillers (19.50%), spike length (6.52%), number of grains per spike (3.07%), thousand grain weight (6.42%), biological (9.43%) and economic yield (13.92%) as compared to control treatment. Moreover, biochar significantly improved water use efficiency and physiological attributes of drought stressed wheat. Principal component analysis linked different scales of study and demonstrated the potential of physio-biochemical traits to explain the wheat yield variations under drought condition with response to biochar application. In crux, biochar application (37.18 g kg⁻¹) can be used as an effective stratagem to achieve improved wheat grain yield through mitigating the adverse effects of drought stress.     

Multi-walled carbon nanotubes for plasmid delivery into Escherichia coli cells

Introduction of foreign genes into bacterial cells (transformation) is used for supplementing defective genes or providing additional biological functions. Transformation can be achieved using either chemical or physical methods, e.g., electroporation. Bulk electroporation offers several advantages over chemical methods, including high transformation efficiency, but its application is limited due to the high numbers of cells and plasmids needed as a result of the high death rate of cells during this process, and the difficulty in electroporating single cells. Synthetic inorganic gene nanocarriers have received limited attention in the transformation of bacterial cells. Here we present a plasmid delivery system based on water dispersible multi-walled carbon nanotubes (CNTs) that can simultaneously target the bacterial surface and deliver the plasmids into the cells via temporary nanochannels across the cell envelope. Transformation experiments performed on E. coli provide evidence for the high potential of CNTs for nanoscale cell electroporation.     

No-wash protein labeling with designed fluorogenic probes and application to real-time pulse-chase analysis

Small molecule labeling techniques for cellular proteins under physiological conditions are very promising for revealing new biological functions. We developed a no-wash fluorogenic labeling system by exploiting fluorescence resonance energy transfer (FRET)-based fluorescein-cephalosporin-azopyridinium probes and a mutant β-lactamase tag. Fast quencher elimination, hydrophilicity, and high resistance against autodegradation were achieved by rational refinement of the structure. By applying the probe to real-time pulse-chase analysis, the trafficking of epidermal growth factor receptors between cell surface and intracellular region was imaged. In addition, membrane-permeable derivatization of the probe enabled no-wash fluorogenic labeling of intracellular proteins.     

Growth and production of buckwheat (Fagopyrum esculentum) treated with reduced, ambient, and enhanced UV-B radiation

The effect of enhanced UV-B radiation on buckwheat (Fagopyrum esculentum Moench. variety 'Darja'), an important high elevation crop, was studied in order to estimate its vulnerability in changing UV-B environment. Plants were grown in outdoor experiments from July to October under reduced and ambient UV-B levels, and an UV-B level simulating 17% ozone depletion in Ljubljana. During the development the following parameters were monitored: light saturated photosynthetic activity, transpiration, potential and effective photochemical efficiencies of photosystem II, the contents of photosynthetic pigments and methanol soluble UV-B absorbing compounds. At the end of the experiment, growth rate and production of seeds were estimated. In the following growth season the seeds collected from plants exposed to different UV-B treatments were tested for germination capacity. Total UV-B absorbing compounds during plant development were increased by UV-B radiation, photosynthetic pigments (chlorophyll a and b and carotenoids) decreased. Photosynthetic rate was lowered in an early stage of development. UV-B treatment resulted in the increase in the transpiration rate and consequently the decrease in water use efficiency (WUE). The disturbances in water economy and in photosynthesis affected the reproduction potential negatively; the production of seeds in plants cultivated under ambient and enhanced UV-B was 57 and 39% of the production of specimens treated with reduced UV-B, respectively. The germination of seeds collected from treated plants revealed on average about 95% success, independently of the treatment, but the time needed for germination was the shortest for seeds developed under enhanced UV-B level treatment. Enhanced UV-B radiation affected water relations and production of buckwheat, but not the potential of seeds for germination.     

18F used as tracer to study water uptake and transport imaging of a cowpea plant

We present the water uptake ability of cowpea (Vigna unguliculata Walp)which has been regarded as one of the most drought resistant species amongthe pulse crops. It has been suggested that in the lower part of the stem,parenchymatous tissue for storing water has been developed for the functionof drought resistance. We confirmed that in this tissue, water amount washigh compared to the other stems by neutron radiography. Then the water uptakemanner was measured by positron emitting tracer imaging system (PETIS) using ¹⁸F labeled water produced by a cyclotron. Comparing the water uptakemanner of cowpea plant with that of common bean, cowpea plant was found tomaintain high water uptake activity after drying treatment, suggesting thehigh drought resistant character.