Edilberto Possamai

Antecipação da colheita na qualidade fisiológica de sementes de soja

HARVEST ANTICIPATION ON THE PHYSIOLOGICAL QUALITY OF SOYBEAN SEEDS The harvest delay starting from the physiological maturity has negative influence in soybean seed quality, due to the exposure to unfavorable environmental conditions. Usually, farmers wait for the decrease in seed moisture levels to begin the harvest process as soon as possible. This research had the objective to analyze the influence of harvest anticipation of soybean seeds at different moisture contents on the physiological quality of seeds produced, in search of better seed moisture contents for earliest harvest considering seed vigor and germination. Then trials were carried out with two soybean cultivars, during 2006/2007 crop year and seeds of each cultivar were harvested at R8 stage, at different seed moisture levels, beginning the operation at 28.5% of water and ending at 14.0%. Quality evaluation was made twice: in April, in order to analyze the initial quality of the samples and, in October, to analyze the influence of storage. In each evaluation period, seed moisture content, germination and tetrazolium viability and vigor were assayed. According to the results obtained, the following conclusion can be drawn: soybean seed harvest time can start at seed moisture content below 22.9%.

Germinação e sanidade de sementes de Bauhinia variegata

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 Tukeys 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.

Germinação, qualidade sanitária e armazenamento de sementes de canafístula (Peltophorum dubium)

The objective of this work was to evaluate the effect of dormancy overcoming treatments and storage environment on physiological and phitopathologic quality of canafistula seeds (Peltophorum dubium). Seeds were submitted to the following treatments of dormnancy superacao: scarification with sandpaper (200); immersion in water at room temperature for 24 and 72 hours; (c) immersion in sulfuric acid for 2, 6, 10, 15, 20 and 30 minutes); immersion in hot water (70, 80 and 90oC); (e) moistening of the substratum with KNO3 solution of (0.2%). Seeds were stored at room temperature and at 10oC for 210 days. Effects of treatments and storage were evaluated by water content, germination test (five replicates of 30 seeds), seedlings length and sanity test (400 seeds), with eight-day incubation. It was used a complete random experimental design for data statistics analysis with a 2 x 14 factorial design (storage conditions x treatments for dormancy overcoming). Means were compared by the Tukey test (P>0.5). Regarding non-stored seeds, the best treatments to overcome dormancy and to promote germination were scarification with sandpaper or sulfuric acid for 15 and 30 minutes; regarding stored seeds, there was immersion in hot water (70 and 80oC). Fungi detected in the samples were Pestalotia sp., Alternaria sp., Rhizopus sp., Nigrospora sp., Curvularia sp., Fusarium sp., Rhizoctonia sp., Aspergillus sp., Cladosporium sp. and Fusarium semitectum.