Number Of Xylem Vessels Research Articles

Histological Variations in Cucumber Grafted Plants and Their Effect on Yield

Cucumber is a vegetable crop of economic importance in Mexico. In 2023, fresh or frozen cucumber and pickle international sales reached USD 783M, placing Mexico in second rank among countries with the highest currency inflow in the world. This crop is mostly grown under protected environments with new production technologies, including rootstocks that are tolerant to biotic and abiotic factors that limit the yield and quality of the harvest. Therefore, the goal of this work was to assess three cucurbits as rootstocks (Cucurbita maxima, Cucurbita moschata and Citrullus lanatus), as well as studying the response of cucumber crop to the tested rootstocks. The following treatments were assessed: T1:PSP = cucumber Cv. Paraizo F1 without rootstock; T2:P/MA = cucumber grafted over Cucurbita maxima; T3:P/MO = cucumber grafted over Cucurbita moschata; T4:P/CL = cucumber grafted over Citrullus lanatus Citroides Var. The assessed variables included the number of fruits per plant (NFPP), fruit weight per plant (PFPP), average fruit weight (PPF), plant dry weight (PSP), xylem vessel area (AVX), number of xylem vessels (NVX), vascular bundle area (AHV) and number of vascular bundles (NHV) in roots (R), basal stalk (TB) and apical stalk (AT). Significant differences among treatments were found in the results for variables: NFPP, highlighting that T2:P/MA was superior by 46.15% versus T1:PSP and by 67.69% versus T3:P/MO. Regarding PFPP, T2:P/MA achieved the highest weight (5445 g), as it proved superior by 99.45% than the cucumber without rootstock (T1:PSP). Regarding PSP, T2:P/MA achieved the highest weight (196.65 g), significantly exceeding T1 by 137.5%. Regarding AVXR, T4:P/CL had the highest value (30,063 µm2). Regarding NHVR, watermelon had (T4:P/CL) 39.33% more vascular bundles than the root system of cucumber (T1:PSP). Treatments T2:P/MA and T4:P/CL had the highest values at AVXTB, while for variable NVXTB, treatments T3:P/MO and T2:P/MA were almost equal, surpassing non-grafted cucumber by 175.47%. However, T2:P/MA showed the greatest AHVTB, and T1:PSP was significantly superior to T3:P/MO, by 34.93%, for NHVTB. Furthermore, positive and significant correlations were found among PFPP, AHVR, and AVXTB, as well as among PSP, AVXTB, and AHVTB. Therefore, we may say that having a larger area of vascular vessels in the roots and a larger area of xylem vessels in the basal stalk leads to higher fruit yields per plant. In the same vein, the use of rootstocks is a sustainable alternative to increase fruit yield.

N-acetylcysteine absorption and its potential dual effect improve fitness and fruit yield in Xylella fastidiosa infected plants.

Xylella fastidiosa is a multi-host bacterium that can be detected in hundreds of plant species including several crops. Diseases caused by X. fastidiosa are considered a threat to global food production. The primary method for managing diseases caused by X. fastidiosa involves using insecticides to control the vector. Hence, it is necessary to adopt new and sustainable disease management technologies to control not only the insect but also the bacteria and plant health. We demonstrated that N-acetylcysteine (NAC), a low-cost cysteine analogue, is a sustainable molecule that can be used in agriculture to decrease the damage caused by X. fastidiosa and improve plant health. Using 15N-NAC we proved that this analogue was absorbed by the roots and transported to different parts of the plant. Inside the plant, NAC reduced the bacterial population by 60-fold and the number of xylem vessels blocked by bacterial biofilms. This reflected in a recovery of 0.28-fold of the daily sap flow compared to health plants. In addition, NAC-treated citrus variegated chlorosis (CVC) plants decreased the oxidative stress by improving the activity of detoxifying enzymes. Moreover, the use of NAC in field conditions positively contributed to the increase in fruit yield of CVC-diseased plants. Our research not only advances the understanding of NAC absorption in plants, but also indicates its dual effect as an antimicrobial and antioxidant molecule. This, in turn, negatively affects bacterial survival while improving plant health by decreasing oxidative stress. Overall, the positive field-based evidence supports the viability of NAC as a sustainable agricultural application. © 2024 Society of Chemical Industry.

Production of tomato seedlings submitted to treatments with foliar application of paclobutrazol

Paclobutrazol (PBZ) is a growth regulator that widely used in horticulture and in the tomato seedling growth to compact the shoots, increase the stem diameter and, root biomass, allowing more tolerance of the seedlings against adverse weather conditions. The objective of this work was to evaluate the rates of paclobutrazol (0, 4, 7, 10 and 13 mg L-1) applied 15 days after sowing by foliar spray on the growth, chemical composition and xylem vessel number of tomato seedlings cultivated in two periods. The PBZ regardless of the application rate reduced the height of tomato seedlings in both growth periods. The basal stem diameter and leaf area were increased with 13 mg L-1 of PBZ. The lignin percentage also increased with 10 and 13 mg L-1 of PBZ as compared to control for both periods. The number of xylem vessel was not affected by PBZ application on the seedlings in the first period. PBZ application at rates of 7 and 10 mg L-1 increased the xylem vessel number in the second period. In general, the application of 13 mg L-1 of PBZ generated seedling more robust to overcome climate adversities.

Effects of Selenium on the Lignin Deposition Pattern and Stem Mechanical Properties of Alfalfa (Medicago sativa L.).

Lignin provides structural support to plants; however, it reduces their utilization rate. According to our previous studies, selenium (Se) reduces lignin accumulation in alfalfa, but the specific mechanism involved remains unclear. Therefore, at the seedling stage, four root irrigation treatments using 2.5, 50, and 5 μmol/L sodium selenite (S-RI), selenomethionine (SS-RI), Se nanoparticles (SSS-RI), and deionized water (CK-RI) were performed. At the branching stage, four treatments of foliar spraying with the three Se fertilizers described above at a concentration of 0.5 mmol/L (S-FS, SS-FS, and SSS-FS) and deionized water (CK-FS) were administered. The results revealed that all Se treatments chiefly reduced the level of deposition of syringyl (S) lignin in the first internode of alfalfa stems. SS-FS and SSS-FS treatments mainly reduced the deposition of S and guaiacyl (G) lignins in the sixth internode of alfalfa stems, respectively, while S-FS treatment only slightly reduced the deposition of G lignin. S, SS, and SSS-RI treatments reduced the level of deposition of S and G lignins in the sixth internode of alfalfa stems. Se application increased plant height, stem diameter, epidermis (cortex) thickness, primary xylem vessel number (diameter), and pith diameter of alfalfa but decreased primary xylem area and pith parenchyma cell wall thickness of the first internode, and SS(SSS)-FS treatment reduced the mechanical strength of alfalfa stems. Therefore, Se application could decrease lignin accumulation by regulating the organizational structure parameters of alfalfa stems and the deposition pattern of the lignin monomers.

WALL-ASSOCIATED KINASE Like 14 regulates vascular tissue development in Arabidopsis and tomato

Initiation of plant vascular tissue is regulated by transcriptional networks during development and in response to environmental stimuli. The WALL-ASSOCIATED KINASES (WAKs) and WAK-likes (WAKLs) are cell surface receptors involved in cell expansion and defence in cells with primary walls, yet their roles in regulation of vascular tissue development that contain secondary walls remains unclear. In this study, we showed tomato (Solanum lycopersicum) SlWAKL2 and the orthologous gene in Arabidopsis thaliana, AtWAKL14, were specifically expressed in vascular tissues. SlWAKL2-RNAi tomato plants displayed smaller fruit size with fewer seeds and vascular bundles compared to wild-type (WT) and over-expression (OE) lines. RNA-seq data showed that SlWAKL2-RNAi fruits down-regulated transcript levels of genes related to vascular tissue development compared to WT. Histological analysis showed T-DNA insertion mutant wakl14–1 had reduced plant stem length with fewer number of xylem vessels and interfascicular fibres compared to WT, with no significant differences in cellulose and lignin content. Mutant wakl14–1 also showed reduced number of vascular bundles in fruit. A proWAKL14::mCherry-WAKL14 fusion protein was able to complement wakl14–1 phenotypes and showed mCherry-WAKL14 associated with the plasma membrane. In vitro binding assays showed both SlWAKL2 and AtWAKL14 can interact with pectin and oligogalacturonides. Our results reveal novel roles of WAKLs in regulating vascular tissue development.

Ectopic expression of TTP gene from human in poplar promotes xylem differentiation and confers plant drought tolerance.

The CCCH zinc finger proteins play critical roles in a wide variety of growth, development, and stress responses. Currently, limited reports are available about the roles of animal CCCH proteins in plants. In this study, we report the identification of human TTP (hTTP) with functional similarity to PdC3H17 in a hybrid poplar. hTTP and PdC3H17 shared highly similar tandem CCCH zinc-finger RNA-binding domains. The fragments excluding the CCCH domain of both hTTP and PdC3H17 possessed transcriptional activation activities in yeast cells. Compared to the controls, ectopic expression of hTTP in poplar caused dwarfism, and resulted in significant increases in stem xylem vessel number and photosynthetic and ROS-scavenging abilities, thereby enhancing plant tolerance to drought stress. Our results suggest that hTTP may perform a function in poplar through the PdC3H17-mediated system, and provide an example for the application of animal genes in plants.

Grafting Compatibility and Environmental Conditions on Soilless Eggplant (Solanum melongena) Grown in the Mediterranean Greenhouse

Grafting techniques represent an efficient tool to enhance plant growth and development. The study aims to explore the effects of different grafting combinations on the growth of eggplants under diverse greenhouse conditions. Eggplant cultivar Black bell (Bb) was employed as scion, while the hybrid F1 Beaufort (Be) and Solanum torvum (To) were utilized as rootstock. The hypothesis behind this study pertains to grafting incompatibility with Beaufort F1. It postulates that this incompatibility can be mitigated by manipulating soil and greenhouse temperatures. The experimental factors encompassed plant combinations (Bb, Be/Bb and To/Bb), as well greenhouse and substrate temperature (both cold or heated). The Be/Bb combination showed higher values of plant vegetative traits, but it exhibited low grafting compatibility. Additionally, physiological analysis confirmed the presence of excessive growth and vegetative disorder within the Be/Bb combination. Examination of the xylem vessels revealed notable differences between the grafting combination involving Bb and the rootstock F1 hybrid Be/Bb, compared to the one with To/Bb and the non-grafted Bb. Specifically, the area, diameter and number of xylem vessels were approximatively 45% higher in Be/Bb than in To/Bb and the non-grafted Bb. Furthermore, a robust linear correlation was observed between plant height with morphometric and physiological traits, except fruits sets. This study lays the basis for a novel protocol for agriculture, addressing the excessive vegetative growth in rootstocks regulating air and substrate temperatures.

Phloem and Xylem Responses Are Both Implicated in Huanglongbing Tolerance of Sugar Belle.

Although huanglongbing (HLB) is a devastating citrus disease, improved tolerant cultivars, such as Sugar Belle (SB) mandarin, have been identified. To understand the responses that HLB-affected SB undergoes, we compared 14CO2 fixation, carbohydrate export, phloem callose accumulation, relative expression of plant defense activators, and anatomical changes between healthy and infected SB trees versus susceptible Pineapple (PA) sweet orange. Eight- to ten-week-old leaves of infected SB showed a 2.5-fold increase in 14CO2 fixation and a 13% decrease in 14C-carbohydrate export, whereas HLB-affected PA presented a decrease of 33 and 50%, respectively. The mean distance of a callose deposit to its closest neighbor was 36% smaller in infected SB versus healthy, whereas in HLB-affected PA, it was 33% higher. Expression of papain-like cysteine proteases (PLCPs) was upregulated in SB but downregulated in PA. Infected SB showed minor alterations in the number of xylem vessels, a 16% larger xylem vessel lumen area, and a 14% increase in the proportional area of the xylem. In contrast, PA showed a 2.4-fold increase in the xylem vessel number and a 2% increase in the proportional xylem area. Three complementary mechanisms of tolerance in SB are hypothesized: (i) increased carbohydrate availability induced by greater CO2 fixation, mild effect in carbohydrate export, and local accumulation of callose in the phloem; (ii) activation of defense response via upregulation of PLCPs, and (iii) increased investment in the xylem structure. Thus, phloem and xylem modifications seem to be involved in SB tolerance.

Xylem formation of Populus euphratica and its response to water-heat factors in the lower reaches of Tarim River, China.

To deeply understand the effects of water and temperature factors on the xylem formation of Populus euphratica, taking the Yingsu section in the lower reaches of Tarim River as an example, we selected micro-coring samples of P. euphratica around monitoring wells F2 and F10 in the 100 and 1500 m distance from the channel of Tarim River. We used wood anatomy method to analyze the xylem anatomy of P. euphratica and its response to water and temperature factors. The results showed that the changes of the total anatomical vessel area and the vessel number of P. euphratica in the two plots were basically consistent during the whole growing season. The vessel number of xylem conduits of P. euphratica increased slowly with the increases of groundwater depth, while the total conduit area increased firstly and then decreased. The total vessel area, minimum vessel area, average vessel area, and maximum vessel area of P. euphratica xylem increased significantly with the increases of temperature in the growing season. The contribution of groundwater depth and air temperature to P. euphratica xylem varied among different growth stages. In the early growing season, air temperature had the largest contribution to the number and total area of xylem conduits of P. euphratica. During the middle growing season, air temperature and groundwater depth jointly affected the parameters of each conduit. During the later growing season, groundwater depth had the largest contribution to the number and total area of conduits. Results of the sensitivity analysis indicated that the groundwater depth sensitive to xylem vessel number change of P. euphratica was 5.2 m and that to the change in the total conduit area was 5.9 m. The temperature sensitive to total vessel area of P. euphratica xylem was 22.0 ℃, and that to average vessel area was 18.5 ℃. Therefore, the sensitive groundwater depth affecting xylem growth was at the range of 5.2-5.9 m, and the sensitive temperature was at the range of 18.5-22 ℃. This study could provide scientific basis for the restoration and protection of P. euphratica forest in the lower reaches of Tarim River.

The effect of salinity on anatomical characteristics of two halophyte species from Turkey

ABSTRACT Anatomical adaptations of vegetative organs of Salicornia perennans Willd. and Suaeda prostrata Pall. subsp. prostrata distributed throughout the Kizilirmak Delta, Samsun were investigated in this study. To examine root, stem, and leaf anatomical modifications, the examined halophytic taxa were collected from the natural salt-affected soils of the study area. Some anatomical differences were detected in the roots, stems, and leaves of the taxa exposed to salinity. High salinity significantly increased the thickness of the periderm and cortex and the width of the aeriferous cavities in the root cortex of Salicornia perennans. The number of xylem vessels increased at higher salinity levels, whereas the diameters of xylem vessels decreased in the roots of Salicornia perennans. The diameters of xylem vessels decreased in the roots of Suaeda prostrata subsp. prostrata. Stem anatomical characteristics such as the thickness of the cuticle, palisade tissue, water-storing parenchyma, and the length and width of lignified cells, were increased by high salinity. Similarly, the thickness of the cortex in the stem of Suaeda prostrata subsp. prostrata was increased at the high salinity level. In addition, many tracheoblasts specific to Salicornia perennans were observed in the palisade tissue. In the leaves of Suaeda prostrata subsp. prostrata, the thickness of palisade tissue, and the succulence were significantly increased with a further increase in salt concentrations. Furthermore, stomata dimensions and stomata indices of both investigated taxa were considerably decreased under high salinity.

Microplastics reduce nitrogen uptake in peanut plants by damaging root cells and impairing soil nitrogen cycling.

Microplastic (MP) pollution severely impairs the sustainable development of modern agriculture. However, the mechanisms underlying the effects of MP contaminants on nutrient cycles in agroecosystems are poorly understood. In this study, we examined the impacts of two types of MPs, polypropylene (PP) and rubber crumb (RC), on nitrogen (N) transformation and N cycling in soil-peanut system. High concentrations of PP (1% w/w) and RC (1% w/w) inhibited vegetative growth and N uptake in peanut plants by damaging root cells and disturbing soil N cycling. These MPs damaged the plasma membranes of root cells and caused oxidative stress, as evidenced by the decreased number of xylem vessels, which in turn inhibited N uptake by roots. Integrated metagenomic and metabolomic analyses revealed that the differential soil metabolite levels in response to MP treatment affected the microbial community structure in the rhizosphere and the expression of key N cycling-related genes, resulting in altered N transformation and the decreased availability of N in rhizosphere soil. These findings provide the first evidence of the effects of MPs on N uptake in peanut plants and shed light on the importance of rational management of MPs for crop growth and yield in agroecosystems.

Biocontrol of root rot in Geranium with antimycotic rhizobateria

Excessive and frequent usage of synthetic fungicides has negative effects on the environment and human health. Biological control is one of the most efficient and environmentally responsible ways to manage plant diseases. In the present study, Bacillus velezensis strain B63, Bacillus subtilis subsp. Spizizenii strain TRC-20S and Serratia sp. Showed antifungal activities against Fusarium semitectum (synonym: Fusarium incarnatum), Macrophomina phaseolina, and Efibula tuberculata (MW063610) (synonym: Phanerochaete tuberculata). These fungi were isolated and purified from rotten geranium roots. M. phaseolina and F. semitectum were identified based on morphological and microscopic features. In addition, E. tuberculata was identified using the PCR technique. Bacillus velezensis strain B63 gave the best results in the terms of a decrease in plant mortality percentage and an increase in the geranium biometric parameters either under greenhouse or under field conditions. In addition, Bacillus velezensis strain B63 successfully increased the activity of defense-related enzymes, peroxidase (POD), and superoxide dismutase (SOD) and boosted the accumulation of total phenolic and flavonoid content in geranium leaves under field conditions. Also, the maximum essential oil yield with the highest eugenol content was recorded due to the application of B. velezensis and B. subtilis. Furthermore, anatomical analysis confirmed the positive role of biological control to induce resistance to root rot diseases through increasing root diameter, cortex thickness, vascular cylinder dimension, mean xylem vessel diameter, and xylem vessel number. Bacillus velezensis strain B63 possesses a broad expanse of antifungal and plant growth-promoting properties and can therefore play a vital role in boosting sustainable agriculture. This strain could be developed and applied in field experiments to improve plant growth and control root rot pathogens.

Physiological, Anatomical, and Agronomic Responses of Cucurbita pepo to Exogenously Sprayed Potassium Silicate at Different Concentrations under Varying Water Regimes

Drought is one of the major environmental stresses that devastatingly impact squash development, growth, and productivity. Potassium silicate can attenuate the injuries caused by water stress. Hence, this study was designed to investigate the influence of three concentrations of potassium silicate; 10, 15, and 20 g/L on squash plants versus untreated control under three irrigation regimes; 100, 75, and 50% of estimated crop evapotranspiration (ET). The obtained results indicated that moderate (75% ET) or severe (50% ET) drought stress conditions gradually declined photosynthetic pigments, relative water content (RWC), mineral content, physiological parameters, and anatomical characteristics. These deleterious impacts were reflected on all growth and yield traits, i.e., plant height, fresh and dry weight of root and shoot, and fruit yield. On the other hand, the antioxidant enzyme activities; superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) significantly increased under severe drought stress at 50% ET followed by 75% ET. However, all evaluated exogenous applications of potassium silicate substantially enhanced photosynthetic pigments, RWC, N, P, and K content, antioxidant enzyme activities, and anatomical characters (periderm thickness, cortex thickness, midrib thickness, mesophyll thickness, number of xylem vessels per main vascular bundle, thickness of vascular bundle, thickness of collenchymatous tissue and upper epidermis, and thickness of collenchymatous tissue and lower epidermis). These desirable impacts were reflected in enhancing all growth and yield parameters. Conclusively, this study alludes that the exogenously applied of potassium silicate, particularly at 20 g/L, can alleviate the deleterious effects of drought stress and enhance the growth and productivity of squash plants, especially in arid environments.

Morphology, biochemistry, and yield of cassava as functions of growth stage and water regime

Water deficit affects morphological attributes and physiological and biochemical processes important to plants. Although cassava crop is known for its rusticity and adaptability to adverse environmental conditions, there have not been any studies reporting the effects of water deficit at different growth stages on cassava morphology and biochemistry. The objective of this research was to evaluate the morphological, anatomical, biochemical, and yield responses of cassava under different water regimes in three growth stages. The experimental design used was completely randomized 3 × 3 factorial scheme consisting of three growth stages (GS) [90–180 (GS3), 180–270 (GS4), and 270–360 days after planting (DAP) (GS5)] and three soil water tensions (-10, -40, and -70 kPa) with five replicates. Plants were affected, mainly in GS3, by -40 and -70 kPa soil tensions, with decreases in stem diameter, plant height and number of leaves. Leaf anatomy was also affected by water deficit in GS3, with reductions in the mesophyll thickness (13.7%), spongy parenchyma (19.9%), epidermal cells on the blade abaxial surface (18.0%) and in the number of xylem vessels (15.8%); in addition, there was an increase in the wall thickness (105.0%) and in the diameter (85.5%) of the xylem vessels. Under prolonged water deficit, there was an increase in the activity of superoxide dismutase and catalase, which were efficient in controlling H2O2. The imposition of water deficit drastically reduced the yield of commercial and tuberous roots in GS3 (82.1% and 65.0%) and GS5 (45.7% and 32.5%). Our study shows that the period of crop susceptibility to water deficit is longer than previously thought, evidencing the need for greater attention to water availability between 90 and 180 and between 270 and 360 DAP, as it may aid in reducing the negative effects of water deficit on the biochemistry, anatomy, and yield components of cassava.

Genome-Wide Identification of Direct Targets of ZjVND7 Reveals the Putative Roles of Whole-Genome Duplication in Sour Jujube in Regulating Xylem Vessel Differentiation and Drought Tolerance.

The effects of whole-genome duplication span multiple levels. Previous study reported that the autotetraploid sour jujube exhibited superior drought tolerance than diploid. However, the difference in water transport system between diploids and autotetraploids and its mechanism remain unclear. Here, we found the number of xylem vessels and parenchyma cells in autotetraploid sour jujube increased to nearly twice that of diploid sour jujube, which may be closely related to the differences in xylem vessel differentiation-related ZjVND7 targets between the two ploidy types. Although the five enriched binding motifs are different, the most reliable motif in both diploid and autotetraploid sour jujube was CTTNAAG. Additionally, ZjVND7 targeted 236 and 321 genes in diploids and autotetraploids, respectively. More identified targeted genes of ZjVND7 were annotated to xylem development, secondary wall synthesis, cell death, cell division, and DNA endoreplication in autotetraploids than in diploids. SMR1 plays distinct roles in both proliferating and differentiated cells. Under drought stress, the binding signal of ZjVND7 to ZjSMR1 was stronger in autotetraploids than in diploids, and the fold-changes in the expression of ZjVND7 and ZjSMR1 were larger in the autotetraploids than in the diploids. These results suggested that the targeted regulation of ZjVND7 on ZjSMR1 may play valuable roles in autotetraploids in the response to drought stress. We hypothesized that the binding of ZjVND7 to ZjSMR1 might play a role in cell division and transdifferentiation from parenchyma cells to vessels in the xylem. This regulation could prolong the cell cycle and regulate endoreplication in response to drought stress and abscisic acid, which may be stronger in polyploids.

Agronomic, anatomic and physiological characterization of Coffea arabica L. genotypes on irrigated system in the Central Cerrado

Due to climatic conditions and the possibility of using machineries, coffee has a potential to achieve high yields with reduced costs, in the biome of Cerrado. Leaf anatomy and physiology can help in the identification of more adapted cultivars to a given environmental condition. The objective is to verify the behavior of Coffea arabica L. genotypes in the Cerrado of the Brazilian Central Plateau through anatomical and physiological characterization and yield. Ten coffee genotypes from the Active Germplasm Bank located in the municipality of Planaltina, Distrito Federal, were evaluated. The genotypes evaluated were: Araponga MG1, Catiguá MG2, Catiguá MG3 P23, Catiguá MG3 P7, Catiguá MG3 P51, Catiguá MG3 P, Catuaí Amarelo IAC 62, Catuaí Vermelho IAC 15, Paraíso MG1 and Topázio MG 1190. The phenotypic characteristics evaluated were the thickness of: adaxial cuticle surface, adaxial and abaxial epidermis surfaces, the palisade and spongy parenchyma, the mesophyll layer, the phloem, number and diameter of the xylem vessels, stomatal density,relationship between the polar and equatorial diameter of the stoma, specific leaf area, stomatal conductance, transpiration rate, net photosynthetic rate, water use efficiency, intercellular carbon concentration and yield. Genotypes of Coffea arabica L. presented a distinction between the characteristics evaluated when grown under climatic conditions of the Brazilian Central Plateau Cerrado, highlighting the variations in the behavior and distinguished adaptation in this environment. The Araponga MG1 genotype stood out for anatomical and physiological characteristics of higher values, such as net photosynthetic rate, stomatal conductance, intercellular carbon concentration, abaxial and adaxial epidermis thickness, stomatal density and number of xylem vessels. The genotype Paraíso MG1 stands out for higher grain productivity. The genotype Catuaí Vermelho IAC 15 stands out for anatomical and physiological characteristics such as higher stomatal density, greater number of xylem vessels and greater efficiency in water use, resulting in improved productivity.Key words: Adaptability; Coffee tree; Morphology; Grain yield; Gas exchange.

Seleção precoce de genótipos de Coffea arabica tolerantes à seca em estágio de mudas utilizando-se divergência funcional

ABSTRACT The development of more drought-tolerant cultivars is essential for the maintenance of global agricultural production. This study aimed to perform an early selection of drought-tolerant Coffea arabica genotypes by evaluating their functional divergence using morphological, anatomical and physiological analyses. Seedlings of 14 genotypes were subjected to the drought stress imposed by irrigation for 18 days. Growth and anatomical parameters, leaf water potential and gas exchanges were measured. Under irrigated conditions and prolonged drought (18 days), the divergence among the genotypes was determined mainly by morphological traits, such as leaf area, stem diameter and, consequently, shoot dry mass. Under moderate drought (14 days), parameters such as water potential, cuticle thickness, stomatal density, number of xylem vessels and water-use efficiency were important for the divergence of the group with the highest ability to maintain its water status. The genotypes 1, 2, 4, 11 and 12 have characteristics that contributed to the maintenance of water status, such as greater cuticle thickness, stomatal density, smaller number of xylem vessels and phloem thickness, bigger root length and greater water-use efficiency. The functional divergence combining morphological, anatomical and physiological analyses in response to the moderate drought indicated the early selection of the genotypes 1, 2,4, 11 and 12 as more drought tolerant during the seedling stage.

Kernel Water Relations and Kernel Filling Traits in Maize (Zea mays L.) Are Influenced by Water-Deficit Condition in a Tropical Environment.

Water deficit is a major limiting condition for adaptation of maize in tropical environments. The aims of the current observations were to evaluate the kernel water relations for determining kernel developmental progress, rate, and duration of kernel filling, stem reserve mobilization in maize. In addition, canopy temperature, cell membrane stability, and anatomical adaptation under prolonged periods of pre- and post-anthesis water deficit in different hybrids was quantified to support observations related to kernel filling dynamics. In this context, two field experiments in two consecutive years were conducted with five levels of water regimes: control (D1), and four water deficit treatments [V10 to V13 (D2); V13 to V17 (D3); V17 to blister stage (D4); blisters to physiological maturity (D5)], on three maize hybrids (Pioneer 30B80, NK 40, and Suwan 4452) in Expt. 1. Expt. 2 had four water regimes: control (D1), three water deficit treatments [V10 to anthesis (D2); anthesis to milk stage (D3); milk to physiological maturity (D4)], and two maize hybrids (NK 40 and Suwan 4452). Water deficit imposed at different stages significantly reduced maximum kernel water content (MKWC), kernel filling duration (KFD), final kernel weight (FKW), and kernel weight ear–1 while it increased kernel water loss rate (KWLR), kernel filling rate (KFR), and stem weight depletion (SWD) across maize hybrids in both experiments. The lowest MKWC under water deficit was at D3 in both experiments, indicating that lower KFR results in lowest FKW in maize. Findings indicate that the MKWC (R2 = 0.85 and 0.41) and KFR (R2 = 0.62 and 0.37) were positively related to FKW in Expt. 1 and 2, respectively. The KFD was reduced by 5, 7, 7, and 11 days under water deficit at D3, D4 in Expt. 2 and D4, D5 in Expt. 1 as compared to control, respectively. Water deficit at D5 in Expt. 1 and D4 in Expt. 2 increased KWLR, KFR, and SWD. In Expt. 2, lower canopy temperature and electrical conductivity indicated cell membrane stability across water regimes in NK 40. Hybrid NK 40 under water deficit had significantly higher cellular adaptation by increasing the number of xylem vessel while reducing vessel diameter in leaf mid-rib and attached leaf blade. These physiological adjustments improved efficient transport of water from root to the shoot, which in addition to higher kernel water content, MKWC, KFD, KFR, and stem reserve mobilization capacity, rendered NK 40 to be better adapted to water-deficit conditions under tropical environments.

Plasticity of root anatomy during domestication of a maize-teosinte derived population.

Maize (Zea mays L.) has undergone profound changes in root anatomy for environmental adaptation during domestication. However, the genetic mechanism of plasticity of maize root anatomy during the domestication process remains unclear. In this study, high-resolution mapping was performed for nine root anatomical traits using a maize-teosinte population (mexicana × Mo17) across three environments. Large genetic variations were detected for different root anatomical traits. The cortex, stele, aerenchyma areas, xylem vessel number, and cortical cell number had large variations across three environments, indicating high plasticity. Sixteen quantitative trait loci (QTL) were identified, including seven QTL with QTL × environment interaction (EIQTL) for high plasticity traits and nine QTL without QTL × environment interaction (SQTL). Most of the root loci were consistent with shoot QTL depicting domestication signals. Combining transcriptome and genome-wide association studies revealed that AUXIN EFFLUX CARRIER PIN-FORMED LIKE 4 (ZmPILS4) serves as a candidate gene underlying a major QTL of xylem traits. The near-isogenic lines (NILs) with lower expression of ZmPILS4 had 18-24% more auxin concentration in the root tips and 8-15% more xylem vessels. Nucleotide diversity values analysis in the promoter region suggested that ZmPILS4 was involved in maize domestication and adaptation. These results revealed the potential genetic basis of root anatomical plasticity during domestication.

Effect of Garlic and Licorice Extracts on Vegetative Growth and Leaf Anatomy of Strawberry Plants Cultivated in Different Growing Media

This research was conducted to investigate the effect of garlic cloves extract (GCE) at 50 and 100 g l-1 and licorice root extract (LRE) at 25 and 50 g l-1 as foliar spray treatments on the vegetative growth and leaf anatomy of strawberry plants cultivated in different growing media, i.e. traditional soil (silt : sand 1:1 v/v), solid substrates (Peatmoss, Perlite and vermiculite 1:1:1 v/v/v), hydroponic (DFT technique) during 2017 and 2018 seasons. The growth of strawberry plants cv. festival cultivated in the three assigned growing media was significantly enhanced by the applied GCE and LRE treatments. Significant increases in the fresh and dry weights of root and shoots, root size, number of leaves and total leaves area / plant were obtained with all GCE and LRE treatments, while a significant reduction in roots / shoots ratio was occurred. In addition, both treatments caused a significant increase in the leaf content of photosynthetic pigments, nitrogen, phosphorous, potassium, calcium, magnesium and crude protein compared with the untreated plants. Anatomically, the applied concentrations of both GCE and LRE led to obvious increases in the thickness of mid vein, length and width of main vascular bundle, thickness of phloem and xylem tissues, number of xylem vessels/ bundle and thickness of lamina and its tissue components (upper and lower epidermis and mesophyll tissue). Furthermore, these positive effects of GCE and LRE treatments on the vegetative growth, chemical composition and leaf anatomy were most pronounced with the plants cultivated in solid substrate mixture followed by the plants cultivated hydroponically then those cultivated in traditional soil. Also, LRE at 50 g l-1 was the most effective treatment in this respect followed by LRE at 25 g l-1 then GCE at 50 g l-1 while GCE at 100 g l-1 was the least effective. Therefore, the present study strongly confirm the use of GCE and LRE as healthy safe and eco-friendly treatments to improve growth of strawberry plants whether cultivated in traditional soil or in soil alternatives and also to reduce the risks of using growth regulators for clean and safe agriculture.