The Effect of Exogenous Application of Quercetin Derivative Solutions on the Course of Physiological and Biochemical Processes in Wheat Seedlings

Quercetin, classified as a flavonoid, is a strong antioxidant that plays a significant role in the regulation of physiological processes in plants, which is particularly important in the case of biotic and abiotic stresses. The study investigated the effect of the use of potassium quercetin solutions in various concentrations (0.5%, 1.0%, 3.0% and 5.0%) on the physiological and biochemical properties of wheat seedlings. A pot experiment was carried out in order to determine the most beneficial dose of this flavonoid acting as a bio-stimulant for wheat plants. Spraying with quercetin derivative solutions was performed twice, and physiological measurements (chlorophyll content and fluorescence as well as gas exchange) were carried out on the first and seventh days after each application. The total phenolic compounds content and the total antioxidant capacity were also determined. It was shown that the concentrations of potassium quercetin applied have a stimulating effect on the course of physiological processes. In the case of most of the tested physiological parameters (chlorophyll content and fluorescence and gas exchange) and the total antioxidant capacity, no significant differences were observed in their increase as a result of application with concentrations of 3.0 and 5.0%. Therefore, the beneficial effect of quercetin on the analysed parameters is already observed when spraying with a concentration of 3.0%.     

Low Light Increases the Abundance of Light Reaction Proteins: Proteomics Analysis of Maize (Zea mays L.) Grown at High Planting Density

Maize (Zea mays L.) is usually planted at high density, so most of its leaves grow in low light. Certain morphological and physiological traits improve leaf photosynthetic capacity under low light, but how light absorption, transmission, and transport respond at the proteomic level remains unclear. Here, we used tandem mass tag (TMT) quantitative proteomics to investigate maize photosynthesis-related proteins under low light due to dense planting, finding increased levels of proteins related to photosystem II (PSII), PSI, and cytochrome b₆f. These increases likely promote intersystem electron transport and increased PSI end electron acceptor abundance. OJIP transient curves revealed increases in some fluorescence parameters under low light: quantum yield for electron transport (φE_o), probability that an electron moves beyond the primary acceptor Q_A⁻ (ψ_o), efficiency/probability of electron transfer from intersystem electron carriers to reduction end electron acceptors at the PSI acceptor side (δR_o), quantum yield for reduction of end electron acceptors at the PSI acceptor side (φR_o), and overall performance up to the PSI end electron acceptors (PI_total). Thus, densely planted maize shows elevated light utilization through increased electron transport efficiency, which promotes coordination between PSII and PSI, as reflected by higher apparent quantum efficiency (AQE), lower light compensation point (LCP), and lower dark respiration rate (R_d).     

Physiological and Epigenetic Reaction of Barley (Hordeum vulgare L.) to the Foliar Application of Silicon under Soil Salinity Conditions

Soil salinity is an important environmental factor affecting physiological processes in plants. It is possible to limit the negative effects of salt through the exogenous application of microelements. Silicon (Si) is widely recognized as an element improving plant resistance to abiotic and biotic stresses. The aim of the research was to determine the impact of foliar application of Si on the photosynthetic apparatus, gas exchange and DNA methylation of barley (Hordeum vulgare L.) grown under salt stress. Plants grown under controlled pot experiment were exposed to sodium chloride (NaCl) in the soil at a concentration of 200 mM, and two foliar applications of Si were made at three concentrations (0.05%, 0.1% and 0.2%). Measurements were made of relative chlorophyll content in leaves (CCl), gas exchange parameters (C_i, E, g_s, and P_N), and selected chlorophyll fluorescence parameters (F_v/F_m, F_v/F₀, PI and RC/ABS). Additionally, DNA methylation level based on cytosine methylation within the 3′CCGG 5′ sequence was analyzed. Salinity had a negative effect on the values of the parameters examined. Exogenous application of Si by spraying leaves increased the values of the measured parameters in plants. Plants treated with NaCl in combination with the moderate (0.1%) and highest (0.2%) dose of Si indicated the lowest methylation level. Decrease of methylation implicated with activation of gene expression resulted in better physiological parameters observed in this group of barley plants.     

Genome-Wide Identification and Characterization of Polygalacturonase Gene Family in Maize (Zea mays L.)

Polygalacturonase (PG, EC 3.2.1.15) is a crucial enzyme for pectin degradation and is involved in various developmental processes such as fruit ripening, pollen development, cell expansion, and organ abscission. However, information on the PG gene family in the maize (Zea mays L.) genome and the specific members involved in maize anther development are still lacking. In this study, we identified 55 PG family genes from the maize genome and further characterized their evolutionary relationship and expression patterns. Phylogenetic analysis revealed that ZmPGs are grouped into six Clades, and gene structures of the same Clade are highly conserved, suggesting their functional conservation. The ZmPGs are randomly distributed across maize chromosomes, and collinearity analysis showed that many ZmPGs might be derived from tandem duplications and segmental duplications, and these genes are under purifying selection. Furthermore, gene expression analysis provided insights into possible functional divergence among ZmPGs. Based on the RNA-seq data analysis, we found that many ZmPGs are expressed in various tissues while 18 ZmPGs are highly expressed in maize anther, and their detailed expression profiles in different anther developmental stages were further investigated by using RT-qPCR analysis. These results provide valuable information for further functional characterization and application of the ZmPGs in maize.     

Response of Two Crop Plants,Zea mays L. and Solanum lycopersicum L., to Diclofenac and Naproxen

Among numerous contaminants, the ubiquitous occurrence of nonsteroidal anti-inflammatory drugs (NSAIDs) in the environment and their plausible harmful impact on nontarget organisms have made them one of the most important areas of concern in recent years. Crop plants can also potentially be exposed to NSAIDs, since the concentration of these pharmaceuticals is constantly rising in the surface water and soil. Our goal was to evaluate the stress response of two crop plants, maize and tomato, to treatment with selected NSAIDs, naproxen and diclofenac. The focus of the research was on the growth response, photosynthetic efficiency, selected oxidative stress factors (such as the H₂O₂ level and the rate of lipid peroxidation) as well as the total phenolic content, which represents the non-enzymatic protectants against oxidative stress. The results indicate that susceptibility to the NSAIDs that were tested is dependent on the plant species. A higher sensitivity of tomato manifested in growth inhibition, a decrease in the content of the photosynthetic pigments and a reduction in the maximum quantum efficiency of PSII and the activity of PSII, which was estimated using the F_v/F_m and F_v/F₀ ratios. Based on the growth results, it was also possible to reveal that diclofenac had a more toxic effect on tomato. In contrast to tomato, in maize, neither the content of the photosynthetic pigments nor growth appeared to be affected by DFC and NPX. However, both drugs significantly decreased in maize F_v and F_m, which are particularly sensitive to stress. A higher H₂O₂ concentration accompanied, in most cases, increasing lipid peroxidation, indicating that oxidative stress occurred in response to the selected NSAIDs in the plant species that were studied. The higher phenolic content of the plants after NSAIDs treatment may, in turn, indicate the activation of defense mechanisms in response to the oxidative stress that is triggered by these drugs.     

Response of early maturing maize (Zea mays,L) variety to potassium and zinc fertilization in the Nigerian savanna

A three year field study was conducted at five locations in the Nigerian savanna to evaluate the response of early maturing maize variety to varying rates of K and Zn with a view to establishing the K and Zn requirements for maize production in this zone. Treatments consisted of 4 × 3 factorial combinations of 4 levels of K and 3 levels of Zn.Responses to K and Zn fertilization were sporadic and were obtained only in soils of the Southern Guinea savanna and in the soil formed on sedimentary sandstone. There seem to be no problem at present in soils of the Northern Guinea and Sudan savannas where leaching is less intense. It is inferred from this study that K and Zn deficiences are incipient in the high rainfall soils and in the sandstone derived soils. For these soils, 50 kg K/ha and 2–5 kg Zn/ha is suggested as adequate for an early maturing maize crop. Soil data showed that K and Zn responses can be expected when available K and Zn levels fall below 0.1 meq/100 g and 2 ppm respectively.     

Physiological and Biochemical Parameters of Salinity Resistance of Three Durum Wheat Genotypes

The area of farming lands affected by increasing soil salinity is growing significantly worldwide. For this reason, breeding works are conducted to improve the salinity tolerance of important crop species. The goal of the present study was to indicate physiological or biochemical parameters characterizing three durum wheat accessions with various tolerance to salinity. The study was carried out on germinating seeds and mature plants of a Polish SMH87 line, an Australian cultivar ‘Tamaroi’ (salt-sensitive), and the BC₅Nax₂ line (salt-tolerant) exposed to 0–150 mM NaCl. Germination parameters, electrolyte leakage (EL), and salt susceptibility index were determined in the germinating caryopses, whereas photosynthetic parameters, carbohydrate and phenolic content, antioxidant activity as well as yield were measured in fully developed plants. The parameters that most differentiated the examined accessions in the germination phase were the percentage of germinating seeds (PGS) and germination vigor (Vi). In the fully developed plants, parameters included whether the plants had the maximum efficiency of the water-splitting reaction on the donor side of photosystem II (PSII)–F_v/F₀, energy dissipation from PSII–DI_o/CS_m, and the content of photosynthetic pigments and hydrogen peroxide, which differentiated studied genotypes in terms of salinity tolerance degree. Salinity has a negative impact on grain yield by reducing the number of seeds per spike and the mass of one thousand seeds (MTS), which can be used as the most suitable parameter for determining tolerance to salinity stress. The most salt-tolerant BC₅Nax₂ line was characterized by the highest PGS, and Vi for NaCl concentration of 100–150 mM, content of chlorophyll a, b, carotenoids, and also MTS at all applied salt concentrations as compared with the other accessions. The most salt-sensitive cv. ‘Tamaroi’ demonstrated higher H₂O₂ concentration which proves considerable oxidative damage caused by salinity stress. Mentioned parameters can be helpful for breeders in the selection of genotypes the most resistant to this stress.     

SDG102, a H3K36-Methyltransferase-Encoding Gene,Plays Pleiotropic Roles in Growth and Development of Maize (Zea mays L.)

Although histone lysine methylation has been studied in thale cress (Arabidopsis thaliana (L.) Heynh.) and rice (Oryza sativa L.) in recent years, its function in maize (Zea mays L.) remains poorly characterized. To better understand the function of histone lysine methylation in maize, SDG102, a H3 lysine 36 (H3K36) methylase, was chosen for functional characterization using overexpressed and knockout transgenic plants. SDG102-deficiency in maize caused multiple phenotypes including yellow leaves in seedlings, late-flowering, and increased adult plant height, while the overexpression of SDG102 led to reduced adult plant height. The key flowering genes, ZCN8/ZCN7 and MADS4/MADA67, were downregulated in SDG102-deficient plants. Chromatin immunoprecipitation (ChIP) experiments showed that H3 lysine 36 trimethylation (H3K36me3) levels were reduced at these loci. Perturbation of SDG102 expression caused the misexpression of multiple genes. Interestingly, the overexpression or knockout of SDG102 also led to genome-wide decreases and increases in the H3K36me3 levels, respectively. Together, our results suggest that SDG102 is a methyltransferase that catalyzes the trimethylation of H3K36 of many genes across the maize genome, which are involved in multiple biological processes including those controlling flowering time.     

Response of maize (Zea mays) to phosphorus application on basaltic soils in Northwestern Cameroon

A field trial was conducted on two P sorptive, basaltic soils commonly used for maize production in Northwestern Cameroon. The objective was to determine the maintenance P rates required for adequate P supply in the soils for maize after initial capital dressing applications of P (0, 22, 44, 88 and 132 kg ha^-1) in 1991. These were followed by three supplementary P rates – 0, 44 and 88 kg ha^-1 in 1992. Three crops of maize (cv COCA) were grown to monitor the availability of the residual P. Experimental design was randomized complete block with four replications in 1991 and a split-plot in 1992 and 1993. The soils at the experimental sites were rich in organic P which formed 67% and 57% of total P at Mfonta and Babungo respectively. Laboratory P sorption studies indicated high P requirements by the basaltic soils used in the study. The amounts of P sorbed to attain 0.2 ug g^-1 in soil solution were 1200 ug g^-1 at Mfonta and 600 ug g^-1 at Babungo. In spite of these high P sorption capacities, significant responses to small rates of P application were observed. It was concluded that a sizable proportion of P released from organic P mineralization was used to satisfy P sorption capacity of the soils, resulting in maize response to small rates of fertilizer P application. Residual P effects on maize yield were related to applied P. Bray 1 extractable soil P was weakly related to grain yields (r = 0.136 at Mfonta and r = 0.186 at Babungo). A critical value of 5.5 mg kg^-1 Bray 2 extractable P in the soil was established for maize at Mfonta site. About 44 kg P ha^-1 was recommended for maize at this site when Bray 2 soil P test was below this critical value.     

Growth,Yield and Physiological Characteristics of Maize (Zea mays L.) at Two Different Soil Moisture Regimes by Supplying Silicon and Chitosan

Silicon - Water deficit is an important factor to challenge food security, particularly in arid and semi-arid climates. In present experiment, silicon (Si) and chitosan were evaluated to affect the...     

Modulation Role of Abscisic Acid (ABA) on Growth, Water Relations and Glycinebetaine Metabolism in Two Maize (Zea mays L.) Cultivars under Drought Stress

The role of plant hormone abscisic acid (ABA) in plants under drought stress (DS) is crucial in modulating physiological responses that eventually lead to adaptation to an unfavorable environment; however, the role of this hormone in modulation of glycinebetaine (GB) metabolism in maize particularly at the seedling stage is still poorly understood. Some hydroponic experiments were conducted to investigate the modulation role of ABA on plant growth, water relations and GB metabolism in the leaves of two maize cultivars, Zhengdan 958 (ZD958; drought tolerant), and Jundan 20 (JD20; drought sensitive), subjected to integrated root-zone drought stress (IR-DS) simulated by the addition of polyethylene glycol (PEG, 12% w/v, MW 6000). The IR-DS substantially resulted in increased betaine aldehyde dehydrogenase (BADH) activity and choline content which act as the key enzyme and initial substrate, respectively, in GB biosynthesis. Drought stress also induced accumulation of GB, whereas it caused reduction in leaf relative water content (RWC) and dry matter (DM) in both cultivars. The contents of ABA and GB increased in drought-stressed maize seedlings, but ABA accumulated prior to GB accumulation under the drought treatment. These responses were more predominant in ZD958 than those in JD20. Addition of exogenous ABA and fluridone (Flu) (ABA synthesis inhibitor) applied separately increased and decreased BADH activity, respectively. Abscisic acid application enhanced GB accumulation, leaf RWC and shoot DM production in both cultivars. However, of both maize cultivars, the drought sensitive maize cultivar (JD20) performed relatively better than the other maize cultivar ZD958 under both ABA and Flu application in view of all parameters appraised. It is, therefore, concluded that increase in both BADH activity and choline content possibly resulted in enhancement of GB accumulation under DS. The endogenous ABA was probably involved in the regulation of GB metabolism by regulating BADH activity, and resulting in modulation of water relations and plant growth under drought, especially in the drought sensitive maize cultivar JD20.     

Response of Corn Seedlings (Zea mays L.) to Different Concentrations of Nitrogen in Absence and Presence of Silicon

Silicon - Corn plants are highly demanding of nitrogen and the application of silicon has been studied because it minimizes stress from different natures, and for the better utilization of some...     

Ameliorating Effects of Exogenously Applied Proline on Seed Composition,Seed Oil Quality and Oil Antioxidant Activity of Maize (Zea mays L.) under Drought Stress

This study was carried out to appraise whether or not the exogenous application of a potential osmoprotectant, proline, could ameliorate the adverse effects of drought stress on maize seed and seed oil composition, as well as oil antioxidant activity. Water stress reduced the kernel sugar, oil, protein and moisture contents and most of the seed macro- and micro-elements analyzed in both maize cultivars but it increased the contents of seed fiber and ash. Water stress increased the oil oleic acid content with a subsequent decrease in the amount of linoleic acid, resulting in an increased oil oleic/linoleic ratio for both maize cultivars. However, no variation was observed in oil stearic and palmitic acids content due to water stress. A considerable drought induced an increase in seed oil α-, γ-, δ- and total tocopherols and flavonoids were observed in both maize cultivars. However, oil phenolic and carotenoid content as well as 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity decreased. Foliar-applied proline significantly increased the content of seed sugar, oil, protein, moisture, fiber and ash in both maize cultivars under well irrigated and water deficit conditions. Furthermore, exogenous application of proline increased the oil oleic and linoleic acid contents. The concentrations of antioxidant compounds namely phenolics, carotenoids, flavonoids and tocopherols estimated in the seed oil increased due to foliar-applied proline under water deficit conditions that was positively correlated with the enhanced oil DPPH free radical scavenging activity. Moreover, the increase in the contents of these antioxidant compounds and oil antioxidant activity due to the foliar application of proline was noted to be more pronounced under water deficit conditions.     

The effect of broadcast P applications and small amounts of fertilizer placed with the seed on continuously cropped corn (Zea mays L.)

The response of corn (Zea mays L.) to broadcast P applications and to small amounts of fertilizer placed with the seed (fws) was measured in three field trials conducted for 10 years. Five rates of P (0, 11, 22, 45, and 90 kg ha^–1 yr^–1) were applied with and without 4.0-6.4-3.2 kg N, P, K ha^–1 placed with the seed (fws) in a factorial arrangement of treatments. The fws treatment delayed emergence at all sites, reduced final emergence at two of the three sites, increased seedling dry weights at the 4 to 6 leaf stage and reduced the time to 50% silking at two of the three sites. Ear moisture content at harvest was reduced by fws at all sites which indicated that fws advanced maturity. The fws treatment increased grain yield at two of the sites by 1.3 and 2.3%, respectively. Broadcast P applications increased seedling dry weight at all sites but decreased the time to 50% silking only at one site. Broadcast P decreased ear moisture content and increased grain yield at two sites. There was a significant fws by broadcast P interaction in the most P deficient soil such that response to broadcast P was lessened by fws. The interaction was strongest during the early stages of growth and decreased with maturity resulting in no fws by broadcast P interaction for grain yield.     

Silicon Seed Priming Combined with Foliar Spray of Sulfur Regulates Photosynthetic and Antioxidant Systems to Confer Drought Tolerance in Maize (Zea mays L.)

Silicon - The present study evaluated the effect of silicon (Si) seed priming and sulfur (S) foliar spray on drought tolerance of two contrasting maize hybrids viz. drought tolerant Hi-Corn 11 and...     

Genome-wide Identification and Characterization of FCS-Like Zinc Finger (FLZ) Family Genes in Maize (Zea mays) and Functional Analysis of ZmFLZ25 in Plant Abscisic Acid Response

FCS-like zinc finger family proteins (FLZs), a class of plant-specific scaffold of SnRK1 complex, are involved in the regulation of various aspects of plant growth and stress responses. Most information of FLZ family genes was obtained from the studies in Arabidopsis thaliana, whereas little is known about the potential functions of FLZs in crop plants. In this study, 37 maize FLZ (ZmFLZ) genes were identified to be asymmetrically distributed on 10 chromosomes and can be divided into three subfamilies. Protein interaction and subcellular localization assays demonstrated that eight typical ZmFLZs interacted and partially co-localized with ZmKIN10, the catalytic α-subunit of the SnRK1 complex in maize leaf mesophyll cells. Expression profile analysis revealed that several ZmFLZs were differentially expressed across various tissues and actively responded to diverse abiotic stresses. In addition, ectopic overexpression of ZmFLZ25 in Arabidopsis conferred hypersensitivity to exogenous abscisic acid (ABA) and triggered higher expression of ABA-induced genes, pointing to the positive regulatory role of ZmFLZ25 in plant ABA signaling, a scenario further evidenced by the interactions between ZmFLZ25 and ABA receptors. In summary, these data provide the most comprehensive information on FLZ family genes in maize, and shed light on the biological function of ZmFLZ25 in plant ABA signaling.     

Effect of nitrogen,phosphorus and soil and crop residues management practices on maize (Zea mays L.) yield in ultisol of eastern Cameroon

The shortening of fallow period in several areas in tropical Africa has reduced soil fertility and exposed soils to erosion and run-off. Fertilizer application and crop conservation practices are needeed to sustain high crop yield and to conserve the natural resource base for upland crop production in the continent. Field trials were carried out to evaluate the effect of fertilizer application and soil and crop residues management practices on yield of maize (Zea mays L.) planted on a Plinthudult soil at Bertoua, Eastern Cameroon. Maize yields increased significantly with nitrogen and phosphorus fertilizer application. Under the rainfall pattern prevailing in the area, the amount of nitrogen required for maximum yield was higher in the second season. On the other hand, the amount of phosphorus required for maximum yield appeared to decrease with time. The burning of crop residues and weeds prior to planting together with no-till practive gave higher yield of maize than other soil and crop residues management practices.