Changes in canola plant architecture and seed physiological quality in response to different sowing densities

The aim of this study was to evaluate changes in canola yield components and seed physiological quality in response to different sowing densities. The study was made in a greenhouse at the REIPESOL Company Technological Center, Madrid - Spain, with the commercial "Toccata" hybrid variety. The initial sowing density was 360,000 plants/ha and the plant population was later thinned down to include treatments of 250 and 180 thousand plants/ha. Harvested seeds were sent to the Seed Technology Center Laboratory (CATES) at the Madrid Polytechnic University (UPM) to evaluate changes in plant architecture and yield components, as well as the seed physiological quality of different plant parts. Results demonstrated that canola plants showed changes in morphology and yield components in response to different sowing densities. The population of 250,000 plants/ha showed the best seed yield demonstrating that maximum yield is directly related to a correct sowing density. The number of pods/plant was the most important component for increased seed yield/plant and seed yield/area. The spatial distribution of canola seeds in the plant and canola sowing density did not affect seed physiological quality.

Spatial variability of soil fertility and its relationship with seed physiological potential in a soybean production area

The correlation of soil fertility x seed physiological potential is very important in the area of seed technology but results published with that theme are contradictory. For this reason, this study to evaluate the correlations between soil chemical properties and physiological potential of soybean seeds. On georeferenced points, both soil and seeds were sampled for analysis of soil fertility and seed physiological potential. Data were assessed by the following analyses: descriptive statistics; Pearson's linear correlation; and geostatistics. The adjusted parameters of the semivariograms were used to produce maps of spatial distribution for each variable. Organic matter content, Mn and Cu showed significant effects on seed germination. Most variables studied presented moderate to high spatial dependence. Germination and accelerated aging of seeds, and P, Ca, Mg, Mn, Cu and Zn showed a better fit to spherical semivariogram: organic matter, pH and K had a better fit to Gaussian model; and V% and Fe showed a better fit to the linear model. The values for range of spatial dependence varied from 89.9 m for P until 651.4 m for Fe. These values should be considered when new samples are collected for assessing soil fertility in this production area.

Test of exudates color hues for evaluating the physiological potential of coffee (Coffea arabica L.) seeds

Coffee seeds have slow and irregular germination, losing fast their viability during storage, and the standard germination test of these seeds requires at least 30 days. Besides, the results may not reflect the actual physiological quality of these seeds. The objective of this work was to develop a fast and practical test for evaluating the viability of coffee seeds, which is based on the interpretation of different color hues of exudates from seeds. Coffee seeds of the cultivar Catuai 44 from six lots were submitted to germination, accelerated aging, and electrical conductivity tests. In the exudates color hue test, coffee seeds without the parchment and the silvery pellicle (four replications of 10 seeds each) were distributed on top of paper towels moistened and then maintained into a germinator, at 25 ºC for 24, 48, 72, 96, and 120 h. Three classes of color hues were established: colorless, light color hue, and dark color hue, assigning the values of 0, 1, and 3, for each class, respectively. The proposed exudates color hue test can be recommended for the fast assessment of viability for coffee seeds. The most promising results were obtained for seeds with 12% moisture content, after imbibition periods of 72, 96, and 120 h; and with 30% moisture content, after imbibition periods of 72 and 120 h.

Physiological maturity of fruits and seeds of Poincianella pyramidalis (Tul.) L.P. Queiroz

The Leguminosae family is one of the most representative botanical families of the Caatinga, with 80 endemic species, highlighting the catingueira (Poincianella pyramidalis). The objective of this research work was to study the maturation process of P. pyramidalis seeds based on the physiological maturity. Five harvest of fruits and seeds were carried out, with 15 days interval each, in a period from July to September 2010. The harvests began 75 days after anthesis (d.a.a.) and lasted until 135 d.a.a. Fruits and seeds were subjected to the following assessments: size, moisture content, and dry mass of fruits and seeds; and germination and vigor of seeds (first count of germination, germination speed index, length and dry mass of seedling). Under the environmental conditions of municipality of Soledade, State of Paraiba, Northeast Brazil, the point of physiological maturity of P. pyramidalis seeds occurs at 125 d.a.a., when the maximum accumulation of dry mass is 1.993 g and moisture content is 21%. The ideal point of harvest is between 130 d.a.a and 135 d.a.a., before natural dehiscence, when the moisture content of seeds is between 13.0% and 5.0%.

Assessment of physiological potential of cucumber seeds using the software Seedling Vigor Imaging System® (SVIS®)

The software Seed Vigor Imaging System (SVIS®), has been successfully used to evaluate seed physiological potential by automated analyses of scanned seedlings. In this research, the efficiency of this system was compared to other tests accepted for assessing cucumber (Cucumis sativus L.) seed vigor of distinct seed lots of Supremo and Safira cultivars. Seeds were subjected to germination, traditional and saturated salt accelerated aging, seedling emergence, seedling length and SVIS analyses (determination of vigor indices and seedling growth uniformity, lengths of primary root, hypocotyl and whole seedlings). It was also determined whether the definition of seedling growth/uniformity ratios affects the sensitivity of the SVIS®. Results showed that analyses SVIS have provided consistent identification of seed lots performance, and have produced information comparable to those from recommended seed vigor tests, thus demonstrating a suitable sensitivity for a rapid and objective evaluation of physiological potential of cucumber seeds. Analyses of four-days-old cucumber seedlings using the SVIS® are more accurate and growth/uniformity does not affect the precision of results.

Physiological quality, content and activity of antioxidants in soybean seeds artificially aged

The objective of this study was to evaluate physiological quality, content, and activity of antioxidants, in soybean seeds subjected to accelerated aging during different periods. Seeds of cultivars BRS 258, BRS 262 and BRS 268, subjected to accelerated aging during 12, 24, 36 and 48 hours and non-aged seeds were used. After each aging period, the seed were evaluated by tests of: germination; first count and tetrazolium. The total of phenolic compounds, total flavonoides, total of isoflavones, and activity for eliminating ABTS●+ radicals were quantified. There were differences among cultivars according to vigor and viability only after seeds were aged. Cultivars BRS 158 and BRS 268 have shown better seed physiological quality in each aging period; however, not presenting higher amounts of isoflavones and efficiency in removing free radicals. For all cultivars, the values for total of phenolic compounds, as well as total of flavonoids have shown quadratic positive behavior; the values for isoflavones remained constant and the vigor and viability showed contrary trend to activity of antioxidant agents.

Physiological quality of coffee seeds produced under different levels of solar radiation and maturation stages

In Brazil, although the coffee plantations are predominantly grown under full sunlight, the use of agroforestry systems can lead to socioeconomic advantages, thus providing a favorable environment to the crop by promoting its sustainability as well as environmental preservation. However, there is a lack of information on physiological quality of the coffee seeds produced under different levels of solar radiation. Within this context, the objective of this study was to evaluate the influence of different levels of solar radiation and maturation stages on the physiological quality of coffee (Coffea arabica L.) seeds, cv. Acaiá Cerrado MG-1474. Three levels of solar radiation (plants grown under full sunlight; under plastic screens of 35% shading; and under plastic screens of 50% shading) and three maturation stages (cherry, greenish-yellow and green) were assessed. Physiological quality of seeds was assessed by using germination test, first count of germination, abnormal seedlings, dead seeds, and seedlings with open cotyledonary leaves. Electrophoretic analysis of isoenzymes catalase, esterase, superoxide dismutase and peroxidase was also performed. With the evolution of development the coffee seeds presents increases on physiological quality, and at its beginning the seeds show improvements on quality with the reduction of solar radiation.

Physiological potential of Brachiaria brizantha cv. Marandu seeds kept in contact with phosphatic fertilizers

The effect of mixture of seeds of Brachiaria brizantha, cv. Marandu, with different sources, granulometry, and phosphatic fertilizer doses during various periods of exposure on the physiological potential of the seeds has been assessed. The treatments consisted in seed exposure during periods of 0, 3, 6, 12, 24, 36, 48, 72, 96, and 120 h to the following fertilizers: ground granulated single superphosphate (SS), and powdered (SSp); and ground granulated ammonium monophosphate (AMP), at doses of 40 and 80 kg P2O5 ha-1. Tests of germination, tetrazolium, moisture content, and vigor (first count, electrical conductivity, emergence, emergence speed, and fresh mass of seedlings) were performed. It has been concluded that seed physiological potential of B. brizantha cv. Marandu is reduced with increase on the exposure period to phosphatic fertilizer. Such effect, however, is dependent on the product source, granulometry, and dose. SSp was the most harmful to seeds, followed by SSp and AMP, respectively. Moreover, considering a 60% germination rate as acceptable, it may be inferred that seeds can be kept in contact with AMP and SSp, in dose of 80 kg of P2O5 ha-1, respectively, for periods of 71.2 and 16.2 hours.

Physiological maturity of eggplant seeds

Determination of seed physiological maturity and ideal moment for harvesting fruits to extract their seeds are important aspects to produce seeds with high quality. To identify the best period for harvesting eggplant fruits, associated with ideal resting period of the fruit for extracting seeds, an eggplant production field was installed in municipality of Ijaci, in the State of Minas Gerais, Southwestern Brazil. The fruits were harvested at periods of 49, 56, 63, 70, and 77 days after pollination (DAP). The seeds of fruits harvested in each period were manually extracted immediately after harvest or after a post-harvest resting period of seven days, under a shed. The physiological quality of seeds was assessed by tests of: germination percentage; germination and emergence speed indexes; and electrical conductivity; which were carried out in the Central Seed Laboratory, Federal University of Lavras. Electrophoretic analyses of isoenzymes: catalase (CAT); esterase (EST); superoxide dismutase (SOD); and peroxidase (PO), were also therein performed. Results of germination and vigor of seeds have showed that the best period for harvesting the fruit is around 70 DAP; and that seeds should be extracted immediately after harvest. Electrophoretic analysis of enzymes has showed immaturity for eggplant seeds, harvested after 49 DAP.

Physiological potential of rice seeds treated with rhizobacteria or the insecticide thiamethoxam

Development of new technologies, aiming at increasing productivity in different crops, involves constant research on the effectiveness and application of these techniques in seed treatment. In this study, it was aimed at evaluating physiological potential of rice seeds treated with plant growth-promoting rhizobacteria (PGPR) (strains DFs185, DFs223, DFs306, DFs416), or with two dosages of the insecticide thiamethoxam. The variables assessed were: germination (G); first count of germination (FCG); cold test (CT); length of seedlings aerial parts (LAP), root system (LRS), and total length (TL); emergence speed index (ESI); emergence (E), at 14 days; and dry phytomass (DP). Treatments have had a positive effect on percentage of G, FCG and E. The strain DFs185 has promoted increase in percentage emergence, for five of the six lots assessed. The variables: LAP; LRS; TL; ESI; and DP have undergone low or none influence of treatments; and there has been no toxic effect of rhizobacteria or insecticide thiamethoxam. In the cold test, a negative effect of treatments has been detected. Seed treatment with rhizobacteria, as well as with thiamethoxam, improve quality of low quality rice seeds. The strain DFs185 is promising for treating rice seeds, once it stimulates seed germination and emergence.

Computerized imaging analysis of seedlings for assessment of physiological potential of wheat seeds

Nowadays, image analysis is one of the most modern tools in evaluating physiological potential of seeds. This study aimed at verifying the efficiency of the seedling imaging analysis to assess physiological potential of wheat seeds. The seeds of wheat, cultivars IAC 370 and IAC 380, each of which represented by five different lots, were stored during four months under natural environmental conditions of temperature (T) and relative humidity (RH), in municipality of Piracicaba, Stated of São Paulo, Brazil. For this, bimonthly assessments were performed to quantify moisture content and physiological potential of seeds by means of tests of: germination, first count, accelerated aging, electrical conductivity, seedling emergence, and computerized analysis of seedlings, using the Seed Vigor Imaging System (SVIS®). It has been concluded that the computerized analyses of seedling through growth indexes and vigor, using the SVIS®, is efficient to assess physiological potential of wheat seeds.