Phosphate Fertilization and Mycorrhizal Inoculation Increase Corn Leaf and Grain Nutrient Contents

The agricultural use of arbuscular mycorrhizal fungi, such as Rhizoglomus intraradices, can increase the efficiency of phosphate fertilization for the benefit of the corn plant and grain nutrition. In this study, a field experiment was conducted in an area of Selvíria/MS, Brazil, in the years 2019 and 2020, to verify the effects of reduced doses of phosphorus combined with the inoculation of corn seed with R. intraradices on corn plant growth and grain nutrient contents. The experiment was laid in a randomized block design in subdivided plots with four repetitions and twenty treatments resulting from combining five doses of P2O5 (0%, 25%, 50%, 75%, and 100% of the recommended dose) with four doses (0, 60, 120, and 180 g ha1) of an inoculant containing R. intraradices. Leaf and kernel macro- and micronutrient contents were evaluated. The foliar P content in 2020 was a function of the interaction between phosphate fertilization and AMF inoculation, with the highest leaf P content observed at the 100% of P2O5 combined with AMF inoculation between 120 and 140 g ha1. In the grains Mg content, an interaction was observed between the two factors in 2020 and the response surface, showing that the highest Mg content was obtained when maximum doses of P2O5 and maximum doses of inoculant were combined. A response surface showed that, in 2020, the highest leaf Zn content occurred when 35–55% P2O5 is applied with no inoculation and when P2O5 is limited to 20–30%, and there is inoculation with doses between 90 and 150 g ha1. Phosphate fertilization increased foliar K (2019) and Mg (2020) contents, with maximum points at doses of 76.57% and 88.80%, respectivelyinfo:eu-repo/semantics/publishedVersio

Germinação e sanidade de sementes de Bauhinia variegata Germination and sanity of seeds of Bauhinia variegata

As bauínias são consideradas pioneiras tardias na escala de sucessão vegetal, pois têm crescimento moderadamente rápido. Podem ser utilizadas como planta forrageira, ornamental, para papel e celulose, madeira serrada e roliça e também para recuperação de áreas degradadas. Buscando-se alternativas por meio de métodos de escarificação, para uma germinação rápida e uniforme, sementes de Bauhinia variegata foram submetidas aos seguintes tratamentos pré-germinativos: escarificação mecânica com lixa 220; imersão em água quente a 80 ºC; imersão em água fria a 10 ºC durante 2 h; corte com tesoura na região oposta à micrópila; imersão em ácido sulfúrico concentrado por 5 min seguida de lavagem em água corrente; e imersão em ácido sulfúrico concentrado por 20 min, seguida de lavagem em água corrente. Em seguida, as sementes foram colocadas para germinar em caixas plásticas tipo gerbox em substrato de vermiculita sob temperatura constante de 30 ºC, com avaliações aos sete e 14 dias, e semeadas em bandejas de isopor em areia em casa de vegetação. Avaliaram-se, em casa de vegetação, a porcentagem final de emergência aos 32 dias após a semeadura e o índice de velocidade de emergência. Foi realizado, ainda, o teste de sanidade (Blotter Test) com 400 sementes, pelo método de papel-filtro (Blotter test). Para o teste de germinação e índice de velocidade de emergência foram utilizadas cinco subamostras de 30 sementes de cada tratamento, sendo o experimento conduzido em delineamento inteiramente casualizado, em comparação com as médias pelo teste de Tukey (P>0,05). Constatou-se que a escarificação mecânica (lixa e corte com tesoura) e a imersão em água fria promoveram a germinação das sementes. No entanto, os valores foram semelhantes, estatisticamente, à testemunha; a velocidade de germinação em laboratório foi maior quando as sementes foram escarificadas com lixa ou imersas em água fria por 2 h; o tratamento com ácido sulfúrico (20 min) prejudicou o índice de velocidade de emergência em bandejas; os fungos detectados nas sementes foram Trichothecium sp, Aspergillus sp, Cladosporium sp, Colletotrichum sp, Fusarium sp., Penicillium sp e Rhizopus sp, mas não exerceram efeito na germinação e vigor das sementes.<br>Bauhinia trees are considered late pioneers in plant succession, since they grow moderately fast. They can be used as grazing plants, ornamental, paper and cellulose, round log or sawn wood and also for recovery of degraded areas. Seeking alternatives for a faster and more uniform germination by means of scarification methods, Bauhinia variegata seeds were subjected to the following pre-germination treatments: mechanical scarification (sandpaper 220); immersion in hot water at 80ºC; immersion in cold water (10ºC) for 2 hours; scissors cuttings (area opposed to the micropyle); immersion in concentrated sulfuric acid for five minutes followed by washing in running water; immersion in concentrated sulfuric acid for 20 minutes followed by washing in running water. Seeds were then placed in plastic gerbox boxes with vermiculite substratum to germinate at 30ºC, evaluations were carried out on the 7th and 14th days. Seeds were also sown in trays containing sand in the greenhouse. The parameters index of emergence speed and percent final emergence at 32 days after sowing were evaluated in greenhouse. Seed sanity was evaluated with 400 seeds using the Blotter test. Five sub-samples of 30 seeds from each treatment were used for the germination test and emergence speed index; the experiment was arranged in a complete randomized design and means were compared by the Tukey's Test (P>0.05). Seed germination with mechanical scarification (with sandpaper and scissors cuttings) and immersion in cold water was no significantly different from the control; the germination speed in laboratory was higher when seeds were scarified with sandpaper or immerged in cold water for two hours; the treatment with sulfuric acid (20 minutes) impaired seedling emergence speed; Trichothecium sp, Aspergillus sp, Cladosporium sp, Colletotrichum sp, Fusarium sp., Penicillium sp and Rhizopus sp were the fungus species found in the seeds, however without affecting germination and vigor