Castor (Ricinus communis L.) is one of the oldest cultivated crops, but currently it represents only 0.15% of the vegetable oil produced in the world. Castor oil is of continuing importance to the global specialty chemical industry because it is the only commercial source of a hydroxylated fatty acid. Castor also has tremendous future potential as an industrial oilseed crop because of its high seed oil con- tent (more than 480 g kg -1 ), unique fatty acid composition (900 g kg -1 of ricinoleic acid), potentially high oil yields (1250-2500 L ha -1 ), and ability to be grown under drought and saline conditions. Th e scientifi c literature on castor has been generated by a relatively small global community of researchers over the past century. Much of this work was published in dozens of languages in journals that are not easily accessible to the scientifi c community. Th is review was conducted to provide a compilation of the most relevant historic research information and defi ne the tremendous future potential of castor. Th e article was prepared by a group of 22 scientists from 16 institutions and eight countries. Topics discussed in this review include: (i) germplasm, genetics, breeding, biotic stresses, genome sequencing, and biotechnology; (ii) agronomic production practices, diseases, and abiotic stresses; (iii) management and reduction of toxins for the use of castor meal as both an animal feed and an organic fertilizer; (iv) future industrial uses of castor including renew- able fuels; (v) world production, consumption, and prices; and (vi) potential and challenges for increased castor production.

A Review on the Challenges for Increased Production of Castor

This paper is the second in a series focused on providing a stable platform for the taxonomy of phytopathogenic fungi. It focuses on 25 phytopathogenic genera: Alternaria, Bipolaris, Boeremia, Botryosphaeria, Calonectria, Coniella, Corticiaceae, Curvularia, Elsinoe, Entyloma, Erythricium, Fomitiporia, Fulviformes, Laetisaria, Limonomyces, Neofabraea, Neofusicoccum, Phaeoacremonium, Phellinotus, Phyllosticta, Plenodomus, Pseudopyricularia, Tilletia, Venturia and Waitea, using recent molecular data, up to date names and the latest taxonomic insights. For each genus a taxonomic background, diversity aspects, species identification and classification based on molecular phylogeny and recommended genetic markers are provided. In this study, varieties of the genus Boeremia have been elevated to species level. Botryosphaeria, Bipolaris, Curvularia, Neofusicoccum and Phyllosticta that were included in the One Stop Shop 1 paper are provided with updated entries, as many new species have been introduced to these genera.

One stop shop II: taxonomic update with molecular phylogeny for important phytopathogenic genera: 26–50 (2019)

A framework for the study of the growth and development of castor plant

One of the most notable effects of silicon on plants is a reduction in the severity of multiple plant diseases caused by pathogenic organisms. For instance, the severity of several rice diseases, such as bacterial blight, brown spot, grain discoloration, leaf scald, leaf and panicle blast, stem rot and sheath blight were suppressed by applying silicon. The reduction in symptom expression is believed to be due to silicon’s effects on multiple defense mechanisms in rice that govern the latent period, lesion size, lesion number, and inoculum production. Although foliar-applied silicon is effective in reducing many foliar diseases, applying silicon to the roots is more effective because it mediates the plant’s defense responses to both foliar and root infections. Applications of silicon can perform as well as fungicides for suppressing plant diseases as well as enhance the resistance of susceptible cultivars to the same level as those that have complete genetic resistance. The application of silicon has value for inclusion in an integrated disease management strategy since this often overlooked, quasi-essential element clearly has the potential to reduced plant disease epidemics.

Silicon Control of Foliar Diseases in Monocots and Dicots

Powdery mildew can cause severe yield losses in bean crops. Limited information about resistance sources, and nature and inheritance of resistance are available to bean breeders and plant pathologist. Sources of resistance were searched in seedling tests under controlled conditions in 44 well-known genotypes and in a Spanish germplasm core collection consisting on 201 accessions. A 0-4 scale was used to describe the infection types (IT) observed. Only six out of the 245 evaluated genotypes showed a complete resistance (IT0) without visible symptoms on the leaves: Amanda, Belneb, Cornell 49242, Negro San Luis, Porrillo Sintetico and the local accession BGE003161. Inheritance of resistance was studied in F2 and F2:3 segregating populations. Observed reactions in the five segregating populations fitted to Mendelian ratios with different modes of inheritance. Results revealed that cultivar Porrillo Sintetico carries two dominant and independent resistance genes: one gene conferring complete resis- tance (IT0), and another gene conferring IT3, charac- terized by a moderate mycelial development on the leaves. Both genes show a dominant epistatic rela- tionship. Inheritance of response to powdery mildew in cv. Cornell 49242 was similar to cv. Porrillo Sintetico although the correspondence with the genes described in Porrillo Sintetico was not established. Line X2776 carries one dominant gene conferring IT3, and shares this gene with cv. Porrillo Sintetico. In cv. Amanda, two complementary genes appear to be involved in resistance to this fungus. This information will be relevant for the implementation of breeding programs focused on the development of cultivars carrying genetic resistance to powdery mildew.

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Genetic resistance to powdery mildew in common bean

The most widely standard used for powdery mildew control on cucurbitaceas is the use of resistant cultivars and systemic fungicides, even though nutrition has been an option. The supply of silicon is benefic to many vegetable species, stimulating growth, yield, photosynthesis and regulation of transpiration; besides, its deposition in the epidermis avoids the invasion of fungus, bacteria and sucking insects. The aim of this experiment was to evaluate the influence of potassium silicate on powdery mildew control, development and yield of zucchini squash, cultivar Caserta. The experiment was conducted at Universidade Estadual Paulista, in greenhouse conditions and with a randomized design, divided in four replications, 11 plants per plot and five treatments: control (water), chemical treatment with fenarimol (2.4 g a.i. 100 L-1) and potassium silicate, in doses 1.5 L ha-1; 2.0 L ha-1 and 2.5 L ha-1. We evaluated the disease severity; gas exchange (net CO2 assimilation rates, transpiration, stomatal conductance and water use efficiency); growth (leaf area ratio, relative growth rate, absolute growth rate, net assimilation rate and specific leaf mass) and yield. The results showed that the foliar application of potassium silicate and fenarimol controlled powdery mildew and had no influence on plant growth. Therefore, the potassium silicate may be used as alternative for control of fungal pathogens and reduced application of chemical products, which provides a greater environmental sustainability. However, it is necessary to be careful with high doses because it was observed that 2.5 L h-1 was harmful to fruit production and gas exchange, despite being effective in controlling powdery mildew. According to this study it is recommended using 2.0 L ha-1 for control of powdery mildew to zucchini squash, and can replace the use of fenarimol, without affecting productivity and development of plants.

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Eficiência do silicato de potássio no controle do oídio e no desenvolvimento de abobrinha de moita

The objective in this work was to evaluate the effects of lime and zinc levels, as well as their interaction on development in castor bean plants. The hypothesis of this work is that the lime levels reduce the zinc availability in soil for the plant. The experiment was carried out under greenhouse conditions without temperature control, in pots with 17 dm3 of 'dystrophic Red Latosol', medium texture. The statistical design was of randomized blocks, in a 3 x 5 factorial scheme, with four replicates. The treatments consisted of liming to reach three basis saturations: 40, 60 and 80%, combined with five zinc levels: 0.5, 1.0, 2.0, 4.0 and 8.0 mg dm-3. Only one plant per pot was grown up to 174 days after emergence (first mature raceme), at which point the morphologic and production components of plants were evaluated. Higher lime levels resulted in greater number of seeds per plant and dry matter of seeds per plant. There was interaction of basis saturation and zinc in plant height, in dry matter of root and in length of raceme (masculine part and total). However, none of these increases reflected a significant difference in weight of 100 castor bean seeds.

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Interação de doses de calcário e zinco nas características morfológicas e nos componentes de produção da mamoneira

The inheritance of resistance to powdery mildew in the pea cultivar MK-10 and some histological aspects of infection were assessed. For the inheritance study, F1, F2, backcrosses and F3 generations of MK-10 crossed with two susceptible populations were evaluated. Histological evaluations included percentage of germinated conidia, percentage of conidia that formed appresoria, percentage of conidia that established colonies, and number of haustoria per colony. Segregation ratios obtained in the resistance inheritance study were compared by Chi-square (×²) test and the histological data were analyzed by Tukey's test at 5% probability. It was concluded that resistance of MK-10 to powdery mildew is due to a pair of recessive alleles since it is expressed in the pre-penetration stage and completed by post-penetration localized cellular death, characteristic of the presence of the pair of recessive alleles er1er1.

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Leandro Augusto Andrade Fumes

Papers

Eficiência do silicato de potássio no controle do oídio e no desenvolvimento de abobrinha de moita

Interação de doses de calcário e zinco nas características morfológicas e nos componentes de produção da mamoneira

Inheritance of resistance to powdery mildew in pea and pathogenesis-related aspects