Root Immersion Research Articles

Bacillus subtilis and Rhizophagus intraradices Improve Vegetative Growth, Yield, and Fruit Quality of Fragaria × ananassa var. San Andreas.

Strawberry cultivation requires strategies that maintain or improve its yield within a scheme in which reducing fertilizers and other chemical products can make its consumption safer and more environmentally friendly. This study aims to evaluate the effect of Bacillus subtilis and Rhizophagus intraradices on strawberry growth, yield, and fruit quality. B. subtilis and R. intraradices were inoculated and co-inoculated under three fertilization levels of 225-100-250, 112-50-125, and 0-0-0 kg∙ha-1 of N, P2O5 and K2O. Vegetative growth was evaluated in plant height (cm), leaf area (cm2), aerial fresh weight (g), aerial dry weight (g), and plant coverage (%) variables. Fruit quality parameters such as total acidity (g∙100 mL-1), soluble solids (Brix°), and firmness (kg) were also determined, as well as the number of fruits per m2 and yield (t∙ha-1). The results showed that the pre-treatment of root immersion in a nutrient solution with B. subtilis and the fractionation of 6 L B. subtilis inoculation per plant at a concentration of 107 CFU∙mL-1, in combination with 225-100-250 kg∙ha-1 of N, P2O5, and K2O, achieved the highest accumulation of dry matter (12.9 ± 1.9 g∙plant-1), the highest number of fruits (28.2 ± 4.5 fruits∙m-2), and the highest yield (7.2 ± 1.4 t∙ha-1). In addition, this treatment increased the soluble sugar content by 34.78% and fruit firmness by 26.54% compared to the control without inoculation. This study highlights the synergistic effect of mineral nutrition and microbial inoculation with B. subtilis in increasing strawberry yield and fruit quality.

Response of chickpea genotypes (Cicer arietinum L.) to the fungi complex that causes wilt

Objective: The objective of the present study was to evaluate the response of 10 chickpea genotypes from INIFAP to the damage caused by the fungal complex. Design/methodology/approach: Seedlings (15-day-old) of 10 genotypes (Blanco Sinaloa '92, Blanoro, Combo 743, CUGA2054, HOGA067, CUGA3168, CUGA08-1210, CUGA09-3160, R-12-1509 and R-12-1507) were inoculated by root immersion in a suspension of mycelial fragments of two isolates (high and low virulence) of each fungi: Fusarium languescens, M. phaseolina, S. rolfsii and S. sclerotiorum. Disease severity evaluation was performed 30 days after inoculation. The entire experiment was performed twice. Results: The genotypes showed greater susceptibility to S. sclerotiorum and S. rolfsii compared to F. languescens and M. phaseolina. The highly virulent isolates caused a significant difference in the severity of the disease in the genotypes evaluated. Findings/conclusions: All chickpea genotypes showed susceptibility to the fungal complex that causes wilt.

Application of green synthesized copper oxide nanoparticles for effective mitigation of Fusarium wilt disease in roots of Cicerarietinum

The study investigated the impact of copper oxide nanoparticles (CuONPs) on Fusarium wilt in chickpea. CuONPs, synthesized using coffee powder, were subjected to washing and sonication using Milli-Q water as the solvent during the purification process. Subsequently the nanoparticles were characterized through UV–vis spectroscopy, DLS, Zeta Potential and FTIR analysis. The NPs exhibited a size range of 85–100 nm with a zeta potential of −25.3 mV. Seven days old chickpea seedlings treated with different concentrations of CuONP (10, 25, 50 ppm) via root immersion showed a significant reduction in Fusarium infection severity. Treatment with 10 and 25 ppm CuONPs led to a remarkable 74.5% and 50% decrease in wilt incidence, along with increased root and shoot length, protein, tannin, phenolics, and flavonoid content in chickpea seedlings, grown in Fusarium infected soil. Enzyme activity (PAL, PPO, NR) was enhanced, while proline, H2O2, and MDA content decreased in 10 and 25 ppm CuONPs treated seedlings. A reduced activity of APX and SOD was also recorded in 10 and 25 ppm CuONPs treated seedlings. Chlorophyll content increased by 50.08% in 10 ppm treated seedlings but decreased with 25 and 50 ppm. The findings emphasize the protective role of copper oxide nanoparticles (CuONPs) at a lower concentration of 10 ppm against Fusarium wilt disease. This protective effect is manifested through the reduction of oxidative stress, decreased wilt incidence, and an increased biomass.

Evaluation of different insecticides and application methods for control of Diloboderus abderus

Diloboderus abderus (Coleoptera: Melolonthidae), commonly known as "isoca", is an insect that lives in the natural field, fulfilling the function of recycling nutrients. It is an important soil pest for crops such as corn, wheat, oats and natural and cultivated grasses in countries such as Argentina, Paraguay, Uruguay and southern Brazil. In the last five years, Montes del Plata has recorded significant losses in young plantations associated with soils with a history of farms, mainly in the southwest region of the country. This damage is associated with the larval phase of the isoca, which develops in the A horizon of the soil, feeding on the roots of the recently planted eucalyptus seedlings, which can cause the death of the tree. For this reason, the objective of this work was to evaluate the control effectiveness of three active ingredients (Imidacloprid, Acetamiprid and Thiamethoxan), and the best application method (foliar, surface application to the soil and root immersion) that would allow protecting the plants in their critical stage. The evaluation was carried out on Eucalyptus plants in pots where three stage-three isocas larvae were placed. After 30 days, the plants were dug up and plant survival, root damage, and larval mortality were evaluated. The results indicated that the three active ingredients were efficient in control, with survival rates of isoca of less than 30%. Thiamethoxan was the most efficient with 100% control of isocas, regardless of the application method. The foliar application method showed the best results with isocas survival rates of less than 15%, regardless of the active ingredient applied. Although it is necessary to continue the research by evaluating different site conditions, application times and doses of active ingredients, the results achieved indicate that the application of Thiamethoxan on the plantation line is the profitable alternative to mitigate losses.

First report of Fusarium equiseti causing root and crown rot in tomato in Mexico.

Tomato (Solanum lycopersicum L.) is one of the most important crops in Mexico due to its economic and nutritional value. Among the main diseases in tomato production is Fusarium wilt, which can cause 60% production losses (Ascencio et al, 2008). Mixed infections of Fusarium species or other fungi genera, would increase disease severity. During April to May of 2021, tomato plants with more than 60 days old, were collected from the main production areas of Aguascalientes (22°03'46.5"N 102°05'17.4"W and 22°04'53.64"N 101°58'55.81"W) and Zacatecas (23°05'59.2"N 102°41'07.3"W and 22°16'52.1"N 102°00'11.8"W) Mexico states. Plants showed main root rot, vascular bundles necrosis with corky appearance, stem crown rot, and ascending yellowing. The main root and stem crown were cut in 0.25 cm2 pieces and disinfested in 2% NaClO for one minute, rinsed with distilled water two times, placed on acidified potato dextrose agar (PDA) medium, and incubated at 25 ± 2°C for 7 days. Characteristic Fusarium growths were purified by hyphal tip on PDA, subsequently pure strains were obtained by single-spore isolation method. Several fungi colonies were obtained, but we focused on the colonies that showed abundant aerial mycelium of white color and irregular growth, which turned yellowish to golden and brown color as it ages. Carnation leaf agar (CLA) medium were used for conidia and sporodochium development. Chains of terminal, intercalary and agglomerated chlamydospores with thick, rough brown walls of 18.9 (7.46) µm in diameter (n=120) were observed in the mycelium. Macroconidia with 5 to 7 septa were 30 to 75 (28.32) µm in long and 1.2 to 4.8 (3.2) µm in wide (n=72). Basal cell developed in foot-shape, apical cell was elongated and slightly curved, and some macroconidia had swollen midd-cell. Sporodochium was orange to brown in color and microconidia were absent (Figure 1). Two representative strains from each state, LCA-3.1 and EMA-1 from Aguascalientes and ECZ-4 and LRZ-6 from Zacatecas, were selected for DNA amplification of ITS, TEF-1α and RPB2 regions, with universal primers ITS1/ITS4, EF1/EF2 and 2-5F2/7cR (White et al.1990; O'Donnell et al. 1998, 2013). PCR products were sequenced by Psomagen, Inc. (USA). The sequences obtained showed 100% of similarity among themselves and within species of the Fusarium incarnatum-equiseti species complex (FIESC) with nucleotide NCBI accessions NR_121457 (Type material) for ITS and MW362069 for TEF-1α; and 99.28% with MN170399 for RPB2 in FUSARIOID-ID database. According to morphological (Leslie and Summerell, 2006) and molecular characteristics, isolates were identified as Fusarium equiseti (FIESC 14). The LCA-3.1 sequences were selected to be deposited in GenBank with accession numbers OM812801 (ITS), OM937108 (TEF-1α) and ON653596 (RPB2). Pathogenicity tests were performed twice, under greenhouse conditions in tomato seedlings of cv. Rio Grande. Five tomato seedlings were inoculated by root immersion method (Lopez et al, 2018) in a 1x106 spores/mL solution for 8 min, and transplanted to 1L pots with sterile peat. Five controls plants were immersed in sterile water. At 14 days after inoculation, a general plant decline and slower growth compared to the control plants were observed. Subsequently, plants showed root rot, vascular necrosis, and a brown ring in stem crown. Controls were symptomless. The fungi were re-isolated from symptomatic plants and were morphologically similar to the inoculated strains. Patel et al. (2017) described the pathogenic and toxic effects of F. equiseti on tomato, causing low seed germination, and low root and shoot growth. This is the first report of F. equiseti causing root and stem rot in tomato plants in Mexico.

In Vitro Evaluation of the Development of Fusarium in Vanilla Accessions

Vanilla is an economically important crop for low-lying humid tropical regions. World demand for natural vanilla is increasing, but cultivated plants face serious phytosanitary problems. The disease known as Fusarium wilt is mainly related to the fungus Fusarium oxysporum f. sp. vanillae, and for its management, the pathogen–host relationship must be understood. Four in vitro multiplied vanilla accessions were evaluated: two Vanilla planifolia from Colombia and Mexico, one from V. odorata, and one (1) F1 hybrid (V. rivasii × V. trigonocarpa). In addition, three isolates of Fusarium from different symptomatic plants present in small-scale agroforestry systems: (1Fov) F. oxysporum f. sp. vanillae from leaf, (2Fov) F. oxysporum f. sp. vanillae from root and (3Fs) F. solani also from root. Plants with two months of growth were inoculated in vitro by immersion of roots, and the development of Fusarium wilt was recorded for 15 days, using a severity scale to describe symptoms and to calculate the area under the disease progress curve (AUDPC). No statistical differences were found when analyzing the interaction between Fusarium isolates and vanilla accessions. However, when independently analyzing the design factor Fusarium isolates, there were significant differences; the 1Fov isolate of F. oxysporum f. sp. vanillae induced the highest symptoms as well as death in some plants of all accessions, while F. solani was considered a secondary pathogen. There were no statistical differences for the vanilla accessions factor, but the values of AUDPC and symptoms observed suggest a slight resistance in all the accessions. Therefore, it is suggested to explore the vanilla gene pool to generate multiplication material with resistance genes and to contribute with genetic improvement to successfully integrate the management of Fusarium wilt in commercial systems.

First Report of Fusarium Wilt of Iholena Banana (Musa spp.) Caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 in China.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), has been considered as the most devastating disease affecting bananas (Musa spp.) worldwide. A highly virulent strain of Foc, known as tropical race 4 (TR4), has been detected in the southeast Asia in the 1990s, and has since spread to western Asia, Australia, the Middle East, southern Africa, and South America (Viljoen et al. 2020). Foc TR4 can cause severe yield losses in Cavendish (AAA), Gros Michel (AAA), Silk (AAB), Pisang Awak (ABB) and Bluggoe (ABB) bananas (Ploetz et al. 2006). However, cooking bananas such as plantain (AAB) and Matooke (AAA) bananas, appear to be resistant (Zuo et al. 2017). Iholena bananas (AAB), a subgroup of varieties related to plantains (also known as Pacific plantains), is an important staple food in the Pacific Islands where it was domesticated. It is also popular in Peru, probably due to its nutritional value (Kepler et al. 2011) and is wildly cultivated in other South American countries (Dita et al. 2013). In December 2019, typical symptoms of banana Fusarium wilt were observed on Iholena accession 'Pacific Plantain' (ITC0210) in experimental fields located in Dongguan, Guangdong Province of China. The symptoms included leaf yellowing and pseudostem splitting. The vascular tissue inside the pseudostems was dark red to brown, and the inner rhizomes yellowish-brown. Vascular tissues from three diseased plants were sampled aseptically and placed on potato dextrose agar (PDA) containing 0.05 g/liter kanamycin. Fungal colonies typical of F. oxysporum developed rapidly, with purple-tinged white aerial mycelia and an abundance of microconidia borne in false heads on short microconidia (Nelson et al. 1983). Chlamydospores were produced singly or in pairs in hyphae and macroconidia. Molecular identification was performed using Foc race 4-specific primers (Lin et al. 2009), Foc TR4-specific primers (Dita et al. 2010), Foc race 1 and Foc STR4-specific primers (Ndayihanzamaso et al. 2020). Amplicons of expected sizes were obtained for Foc TR4 and race 4, but not for Foc race 1 and STR4. Sequencing of theITS and 18S rDNA from the three Iholena isolates and BLAST result showed a 100% similarity to the Foc TR4 reference sequences in GenBank (Foc II5, PRJNA73539 and PRJNA56513) to prove that the isolates were Foc TR4. Pathogenicity of the three isolates from Iholena bananas was determined by infecting 4-month-old Cavendish cv. 'Grand Nain' bananas and three Iholena accessions, 'Pacific Plantain' 'Tigua' and 'Uzakan', under greenhouse conditions by root immersion in a Foc conidial suspension and soil drenching at 106 conidia/ml (Dita, 2010). Control plants were treated with sterile distilled water. Three replications of five plantlets were used for each accession. After 35 days, the inoculated plantlets developed typical Fusarium wilt symptoms such as yellowing of the older leaves and discoloration of the inner rhizome. The control plants did not develop symptoms. To complete Koch's postulates, the fungus was re-isolated from inoculated plants and identified as Foc TR4 by PCR (Dita et al, 2010). The susceptibility of 'Tigua' and 'Uzakan' was also confirmed in Foc TR4-infested field trials, with both accessions developing severe Fusarium wilt symptoms. The susceptibility of Iholena bananas to Foc TR4 is of significant concern to all countries where this subgroup is cultivated for major food source, including Peru and other South American countries.

Reaction of inbred lines of habanero hot pepper (Capsicum chinense Jacq.) to inoculation of Fusarium oxysporum

Objective: To evaluate the reaction of five inbred lines of habanero pepper (Capsicum chinense Jacq.) to the inoculation of Fusarium oxisporum and to identify genotypes with possible levels of resistance to this pathogen. Design/methodology/approach: Samples of hot pepper plant stems with typical symptoms of vascular wilt disease were obtained. Then, due to microscopic morphological characteristics of mycelium and conidia in the samples, patogen was identified as Fusarium oxisporum. By immersion of roots, at a concentration of 1x106 conidia per mL, five inbred lines of habanero pepper were inoculated. In addition to the serrano type cultivar Criollo de Morelos 334 (CM-334). The percentage disease index and area under the disease progress curve (ABCPE) were estimated in a randomized complete block design, with three replicates. Results: Significant differences (p≤0.05) were observed for disease index and ABCPE in the genotypes evaluated; evidencing the difference in the genetic basis of the genotypes and the resistance or susceptibility to Fusarium oxisporum. The CM-334 cultivar, the Habanero 5 and Habanero 8 lines showed the lowest percentage of incidence of the disease (10, 20 and 30%, respectively) and ABCPE of 300, 560 and 880. In turn, lines Habanero 9 and Habanero 6 reached the highest ABCPE values with 2220 and 2190, respectively. Study limitations/implications: The disease resistance response in plants is complex and contains multiple interactions between genes, proteins, and metabolites. Findings/conclusions: The grouping of genotypes according to their reaction to Fusarium wilt disease facilitated the identification of resistant and susceptible lines, which can be considered in subsequent genetic improvement studies for hot pepper cultivation.

Efficiency and delivery methods of Trichoderma harzianum on biological control against southern blight in sweet pepper

Soilborne pathogens are difficult to control with limited options, and it is important to seek effective alternatives for management. The objective of this study was to evaluate the effect of Trichoderma harzianum on the biological control of southern blight. The commercial product Trichodermil, containing the antagonist, was used for in vitro antagonism evaluation, followed by in vivo assays, with different forms of biocontrol application in Capsicum annuum seedlings inoculated with Sclerotium rolfsii. The biocontrol conditions used in the tests were: 1) without inoculation of the pathogen; 2) furrow spraying; 3) foliar spraying; 4) immersion of roots in spore suspension; 5) without biocontrol. The T. harzianum isolate tested produces antifungal metabolites that reduce mycelial growth and germination of the pathogen. In the in vivo tests, an effect of the application in the sowing furrow on the root mass of the plants was observed. However, none of the treatments prevented plant mortality. The biocontrol agent T. harzianum does not work as a stand-alone strategy for management of southern blight, but has potential for use in integrated management programs.

Determination of Resistance Levels to Clavibacter michiganensis subsp. michiganensis in Some Solanum Species

Clavibacter michiganensis subsp. michiganensis (Cmm), is a devastating bacterial disease agent causing bacterial wilt and canker in tomatoes. There is no definitive solution to prevent yield losses by Cmm in tomatoes. Moreover, there is currently no commercially successful Cmm resistant tomato cultivar on the market. Therefore, we aimed to determine the tolerance level of some tomato accessions to Cmm in the present study. For this purpose, we screened seven tomato accessions representing four species (Solanum arcanum, S. habrochaites, S. pennellii, and S. peruvianum) from Peru, Ecuador, and Mexico against the highly virulent isolates Cmm-244 and Cmm-9. A root immersion method was used to identify new sources of resistance to this important disease. Two accessions, S. habrochaites LA1777, and S. arcanum LA2157 were found to be moderate and highly tolerant, respectively, and could serve as tolerance resources for tomato breeding in Türkiye. These materials can also be investigated more extensively to determine their intrinsic Cmm tolerance mechanism.

Organic onion biofortification using microalgae and humic acid

Biofortification can be understood as a strategy to raise nutrients levels in vegetables edible structures, which can positively interfere in human diet. Biofertilizers are an interesting option in alternative production systems, as they can increase food nutritional quality and contribute to plant development, while aiding environment sustainability as natural products. The use of microalgae and humic acid as biofertilizers points to improvements in nutrients and biomolecules content in plants, however, their combined application is still unexplored. In that scenario, it was carried a study with onions about the influence of applications via root immersion in microalgae Scenedesmus subspicatus (Sc) and humic acid (HA) solutions, analyzing possible alterations of macro and micronutrients, total sugars, reducing sugar, free total amino acids, , total soluble solids, soluble proteins and antioxidant capacity in the bulbs. Treatments consisted of one minute seedlings roots immersion from two onion cultivars in solutions containing microalgae and humic acid, and then transplanted to organic system field. There were used three concentrations: control, 0.3 g L-1 Sc + 0.3 g L-1 HA (3SH) and 0.6 g L-1 Sc + 0.6 g L-1 HA (6SH). Results show that the treatments with microalgae with humic acid association were able to increase the content of N, carbohydrates and soluble proteins, also elevating antioxidant activity in onion bulbs.

Morphophysiological, Enzymatic, and Elemental Activity in Greenhouse Tomato Saladette Seedlings from the Effect of Plant Growth-Promoting Rhizobacteria

The tomato is a widely cultivated and consumed vegetable globally. Comarca Lagunera is an important tomato-exporting region of Mexico. Salinity is an abiotic factor that reduces productivity and increases production costs. To advance growing period, there is high demand for the sustainable production of seedlings. Plant-growth-promoting rhizobacteria (PGPR) are characterized by improving plant growth through different mechanisms and can be an option for reducing the misuse of chemical fertilizers. The importance of the application of strains, evaluating various inoculation methods (in seed, soil, foliar spraying, and root immersion), should be evaluated to propose biofertilization packages in a specific crop. Thus, the study aimed to determine the effect of PGPR (Bacillus paralicheniformis, Acinetobacter guillouiae, Aeromonas caviae, and Pseudomonas lini) vs. nutrient solution and distilled water in the seedlings stage of saladette-type tomato on morphophysiological variables, nitrate reductase (NR) enzyme activity, and plant minerals via tissue analysis under greenhouse conditions. The four PGPR were inoculated by different methods (inoculation in seed, sprinkling, and both) in saladette-type tomato seedlings under greenhouse conditions and evaluated in vivo 40 days after sowing for morphophysiological variables, such as seedling height; stem diameter; root displaced volume; fresh and dry weight matter of the leaves, stems, and roots; leaf area; and nitrate reductase enzyme activity. The effect of the inoculation of PGPR showed significant results for Pseudomonas lini vs. the control, with 40% higher values, on average, for plant height, stem diameter, displaced root volume, and fresh weight of root, leaf, and stem. The response of enzymatic and mineral content in seedlings was variable with nutrient solution and significant with distilled water. Studies related to the promotion of plants in the subsequent phenological stages of a tomato, considering the selected PGPR, should be considered in future research.

Impact of Bacillus subtilis strains on survival and reproduction of grapevine phylloxera

Summary Many strains of Plant Growth Promoting Rhizobacteria (PGPR) have the ability to induce the systemic resistance in several pathosystems. This study investigates the protective effect of four strains belonging to Bacillus subtilis (Bs168, Bs2500, Bs2504 and Bs2508) on grapevine roots of the sensitive local grapevine cultivar “Helwani” against phylloxera. Fresh roots were immersed in bacterial suspensions 0, 3, 5 and 15 hours before infesting with phylloxera eggs. Results of biometric measurements showed significant differences in the life cycle of phylloxera between treated and untreated roots. Bacillus strains negatively affected phylloxera development and reproduction. The efficiency of treatment increased when root immersion time in the bacterial suspension increased. On the other hand, there were significant differences between strains in terms of their protective effect against phylloxera, but Bs2508 strain was the most effective especially when the roots were immersed for 15 hours. This study supports previous studies in order to employing PGPR strains as biocontrol agents against pests.

In vitro kultura antera kao efikasno primenjena tehnika za proizvodnju dvostrukih haploida pšenice (Triticum aestivum L.)

In vitro anther culture is the most commonly-used technology for doubled haploid production in wheat (Triticum aestivum L.) and various cereals. The technology application allows the genetic attainment of homozygous pure lines from heterozygous breeding material in a single generation, and has become a rapid alternative to the conventional breeding methods. This technology also contributes to more accurately assess QTL × environmental interactions and has been applied in: genetic researches for marker-trait association study, genomics and as a target for transformation, genetic engineering, gene mapping, and mapping of quantitative trait loci (QTLs). This paper reviews the most important factors that limit the efficiency of winter wheat (Triticum aestivum L.) anther culture, such as genotype dependency and albinism, in addition to other affecting factors including the collection time of tillers and physiological growth environments of plants. Factors that improve the efficiency of wheat anther culture in mitigating both genotypic dependency and albinism have been included in this review, too, for example, genetic improvements by following a strategy to realize this purpose through using responsive breeding material for crossing, application of convenient stress pre-treatments (cold pre-treatments, heat shock treatment, colchicine, hormones, and chemicals) to induce androgenesis, and improvement of the composition of anther culture media and culture conditions. We have also highlighted the methods of chromosome doubling for the haploid wheat produced by anther culture androgenesis, such as spontaneous chromosome doubling or use of colchicine and anti-mitotic chemicals at an early stage of anther culture or as root immersion treatment.

Hyperspectral response of cape gooseberry (Physalis peruviana L.) plants inoculated with Fusarium oxysporum f. sp. physali for vascular wilt detection

This study used greenhouse conditions to determine the hyperspectral responses of cape gooseberry (Physalis peruviana L.) plants inoculated with different Fusarium oxysporum f. sp. physali densities because the causal agent of vascular wilt generates great economic losses for farmers. A completely randomized design with four replicates was established. The evaluated treatments were inoculum densities 0.0, 1.0·103 and 1.0·106 conidia/mL of the pathogen. The inoculation was done with immersion of roots in conidia suspensions. The spectral response was directly measured on the plant leaves with a spectroradiometer. Non-invasive detection in the P. peruviana - F. oxysporum pathosystem with reflectance values was used with different spectral indices related to the visible and Red Edge, which were calculated and correlated with the disease variables. The treatments showed significant differences in the visible spectrum starting 14 days after inoculation with higher reflectance values. The chlorophyll index at the red edge (ChRE), the modified chlorophyll absorption index (MCARI), the simple ratio index (SR) and the Zarco & Miller index (ZM) showed highly significant correlations with the area under the disease progress curve for leaves (AUDPCL), leaf area and fresh weight of the aerial part of the plants. This study showed the potential of spectral patterns for the detection and study of Fusarium wilt in P. peruviana.

Evidence of soil‐located competition as the cause of the reduction of sunflower verticillium wilt by entomopathogenic fungi

AbstractThe increasing limitation of agrochemicals for disease control is a major challenge for European agriculture and a spur to developing environmentally friendly approaches such as biological control. Entomopathogenic fungi, which have been used in the control of insect pests for a long time, also have other uses, such as being antagonists of fungi, including plant pathogens. We determined the in vitro effect of three strains of Metarhizium brunneum and two of Beauveria bassiana against Verticillium dahliae and Cadophora helianthi, causal agents of sunflower wilts. Both M. brunneum and B. bassiana were able to inhibit the mycelial growth of the sunflower pathogens and, according to the dual culture and microscopy results, two types of antagonism were observed as being dependent on the strain: competition and/or antibiosis. Greenhouse experiments showed that, after soil treatments with entomopathogens and plant inoculation by root immersion in conidial suspensions of V. dahliae, the entomopathogens were able to efficiently persist in the soil, and three of the four strains even significantly reduced the severity of symptoms in sunflowers. Interestingly, molecular analysis showed that all the strains were able to establish themselves as endophytes in sunflowers in the absence of V. dahliae. When the plants were inoculated with V. dahliae, we detected the pathogen, but not the entomopathogen, in the sunflowers by molecular methods. The results of this work suggest that the protection conferred by M. brunneum and B. bassiana against verticillium wilt might not be plant‐located, but is probably the consequence of their competition with V. dahliae in the soil.

Isolation and efficacy of the endophytic fungus, Beauveria bassiana (Bals.) Vuillemin on grapevine aphid, Aphis illinoisensis Shimer (Hemiptera: Aphididae) under laboratory conditions

The endophytic fungus, Beauveria bassiana has been found to occur endophytically in hundreds of plant species tissues and has been inoculated for establishment in different plants. It has negative effect on piercing-sucking insects in grapevine plants. Thus, the present study aimed to detect the endophytic fungus, B. bassiana throughout ITS genes analysis in the grapevine plant, Vitis venifera cv. Taify and assess its potential for controlling the grapevine aphid, Aphis illinoisensis Shimer (Hemiptera: Aphididae). The obtained 5 isolates were DNA sequenced for ITS region. Data analysis showed that there were 2 different isolates (accession number: MN900613 for isolate Bb-Taif1 and MN900614 for isolate Bb-Taif2). The values of LC50 were 6.041 × 104, 3.199 × 105 spores/ml while those of LC90 were 6.13 × 106 and 7.474 × 107 spores/ml after 3 days of treatment by Bb-Taif1 and Bb-Taif2, respectively. These values showed that the virulence of Bb-Taif1 isolate was higher in its efficacy than the Bb-Taif2 isolate. Further investigations are needed to evaluate its efficacy on other piercing sucking or chewing insect pests throughout conidia spraying, soil inoculation, and/or root immersion for grapevine plants.

Improving the Efficiency of Colchicine-Based Chromosomal Doubling of Maize Haploids.

Production and use of doubled haploids (DH) is becoming an essential part of maize breeding programs worldwide as DH lines offer several advantages in line development and evaluation. One of the critical steps in maize DH line production is doubling the chromosomes of in vivo-derived haploids so that naturally sterile haploids become reproductively fertile diploids (DH) to produce seed. This step of artificially doubling the chromosomes is labor-intensive and costly; hence, optimizing protocols to improve the doubling success is critical for achieving efficiencies in the DH production pipelines. Immersion of 3–4-day old germinating haploid seedlings in colchicine solution is commonly used for chromosome doubling in large-scale maize DH line production. This manuscript presents a new method of colchicine application to haploid seedlings that showed superior doubling rates compared to other methods like standard seedling immersion, seed immersion, root immersion, and direct application of colchicine solution to the seedlings at V2 stage in the greenhouse trays. The new method involves immersing the crown region of the haploid seedlings along with all the seedling roots at V2 stage in the colchicine solution. Further experiments to optimize this method indicated that increasing colchicine concentration had a very positive effect on overall success rate in chromosomal doubling, while not drastically affecting survival rate. The optimized method showed on average 5.6 times higher overall success rate (OSR) compared to the standard haploid seedling immersion method which was the second-best method in our experiments. This improved method of colchicine application saves resources by reducing the number of haploids to be generated and handled in a maize DH production pipeline.

Design and Fabrication of a Wet Mechanical Brushing Unit for Lye Pre-treated Cassava Root

The design and fabrication of a wet mechanical brushing unit for lye pre-treated cassava root was described in this paper. The objective of this work was to determine the time of reaction, the temperature and the concentration of sodium hydroxide solution that will effectively digest the peel and also the speed of the machine, output size, efficiency of peeling and tuber loss. It was determined that using lye solution to digest cassava root peel depends on the severity of the concentration of the solution and the time of root immersion. From the preliminary labouratory tests carried out, the optimal combination of process parameters in terms of concentration, temperature and time of root immersion for UMUCASS44 in lye are 20%, 60°C and 15 minutes, respectively. These values are sufficient to digest the peels of the root for enhanced brushing.

Biodiversity of Endophytic Fungi from Lowland Tomato Plants and Their Potential as Biological Control Agents for Anthracnose Disease in Chili Plants at Green House

Anthracnose disease is one of important diseases of fruit crops that need to be controlled, influence of chili production in Indonesia, and cause significant yield loses of economic importance. Control of the disease until now using fungicides that have negative impact for the environment and the results have not been satisfactory. Based on that, alternative methods of control are studied. The control method is the use of endophytic fungi that isolated from tomato roots in the lowlands. The purpose of this study was to obtain candidates for endophytic fungi that could potentially be biological agents for controlling anthracnose disease. The stages of the research are antagonism test using dual culture method, identification, application suspension of endophytic fungi using root immersion method. Endophytic fungi be isolated from root lowland tomato plants (Jombang and Kediri) and was cultured on Potato Dextrose Agar (PDA) media to get pure culture so identified based on book Illustrated Genera of Imperfect Fungi by H. L. Barnett, Barry B. Hunter (1998). Chilli plants were inoculated with pathogens (Colletotrichum sp.) using spray techniques on leaves then endophytic fungi was applied. The identification results get Penicillium sp., Aspergillus sp., Fusarium sp., antagonistic test get 7 candidate isolates were able to inhibit the growth of Colletotrichum sp., and application suspension of endophytic fungi showed that J8 had highest potential to suppress anthracnose disease in chili plants at greenhouse (51.94%).