EFFECT OF WATER POTENTIAL ON GERMINATION OF SEEDS OF STYLOSANTHES-GUIANENSIS (AUBL) SW

Effect of water potential on germination of seeds of Slylosanthes guianensis (Aubl.) Sw. To evaluate the water potential effect on germination of S. guianensis two experiments were performed.The first one used osmotic pre-treatment in the imbibition phase and after this period (14 h) the seeds were germinated on filter paper moistened with distilled water. In the second experiment, besides the imbibition phase, seeds were kept in a range of water potentials during all the process. The potentials ranged from 0 to -18 bars, with 3 bars increments, induced by mannitol or by polyethylene glycol. Each treatment was replicated 3 times with 100 seeds per replication. The seeds pre-treated during imbibition had high germination percentage, the highest being the ones in polhyetylene glycol. In the second experiment the polyethylene glycol solutions reduced dramatically the germination percentage in relation to mannitol. From -12 bars on germination ceased in the polyethylene glycol treatments, while in mannitol solution there was 52,67% of germination, in the same water potential.

Effects of maturation and scarification on seed germination of Syagrus schizophylla (Mart.) glass. (Arecaceae)

Syagrus schizophylla (Mart.) Glass. belongs to the Arecaccae family. This palm is native of Brazil and presents great potential for use in gardens and cultivation in pot. Palms species, with relatively few exceptions, can only be propagated from seeds; even so, there are no reports in the literature about the germination of this palm seeds. The seed maturity is a factor that interferes in the success of the germination process. For some species, studies showed that palm seeds germinated better when the fruits were completely ripe (showing full color) and for other, when they were with green coloration. Several species of the Arecaccae family presents physical dormancy of seeds in varied degrees, demanding treatments for improve germination. The objective of this work was to study the effects of maturation and of the scarification on seed germination of S. schizophylla. The experimental design used was a factorial 3 x 2 (3 maturation stadiums: green, half-ripe - yellow and completely ripe - red; and mechanical scarification: with and without), entirely casualized, with four replications of 15 seeds per plot. The seeds (with 32,43% of humidity) were placed in plastic boxes with sand (60% of humidity, placing water according to weight in each three days), under controlled conditions of alternated temperature of 25-35 degrees C, photoperiod of 12 hours. The percentage of germination and the speed germination index (SGI) were evaluated until 79 days. It was observed that, so much for germination percentage as for SGI, there was not significant difference for the interaction among the two factors, maturation stadium and scarification, however, there were significant differences among the maturation stadiums and between seeds scarified or not. The seeds from green fruits presented lower germination percentage and slower germination when compared with seeds from yellow or red fruits; the seeds from yellow or red fruits didn't differ statistically to each other. To seeds scarificated, independently of the maturation stadium, presented germination percentage significantly larger and the germination was significantly faster when compared with the seeds without scarification.

Pollen viability in Syagrus romanzoffiana and S-coronata (Arecaceae)

Palms of the Syagrus genus have several natural hybrids in Brazil. They are widely cultivated around the world as ornamental palm. S. romanzoffiana is the parental of natural hybrids with other Syagrus species that are potentially useful as palm cultivated for heart of palm production. The objective of this work was to evaluate the pollen grains viability got from plants grown in the Experimental Nursery of the FCAVJ/UNESP, Jaboticabal, SP, Brazil. Pollen grains were sampled from inflorescence in three occasions: in the right day of anthesis, one day before and one day after anthesis. For each day, the inflorescence was subdivided in epical, medium and basal portions where pollen grains were collected. The results shown that: a) for S. coronata there was no statistical differences in pollen viability (pollen viability average = 92.89%); b) for S. romanzoffiana the average pollen viability was 87.27%, 87.47% e 86.85% before, during and after the anthesis, respectively. The basal portion pollen grains had lower viability (85.19% - p<0.01) than those from the medium (88.17%) and the apical (88.46%) portion of the inflorescence. These results shown that both species have no problems with pollen viability and can be used as parental of hybrids with other Syagrus species.

Study of seed-germination and etiolation of seedlings in Emilia-sonchifolia (l) dc and Emilia-fosgerbii nicolson (Asteraceae)

The germination of seeds of Emilia sonchifolia (2n) and E. fosgerbii (4n) was analysed and our results indicate that the former present light insensitive seeds and the latter germinated only under continuous white light. The germination of seeds under shade light presented no differences between both species, However under continuous white light, which maintain 70% of Pfr, the velocity of germination was greater in Emilia sonchifolia when compared to Emilia fosbergii, indicating that the threshold of 4n seeds were greater than 2n seeds. The analysis of the fluence response curves for etiolating process indicated that the process presented no differences between both species. The same was observed for the effect of the shade light in the etiolating process.

Seed dispersal and germination of Cryptocarya moschata Nees & Martius Ex Nees, Ocotea catharinensis Mez and Endlicheria paniculata (Sprengel) Macbride (Lauraceae)

Data of seed dispersal and germination of the studied species are presented, comparing both observations from the wild and nursery. Fruits were collected from Carlos Botelho State Park (24 degrees 44' to 24 degrees 03'S, 47 degrees 46' to 48 degrees 10'W), south of São Paulo State, Brazil. O. catharinensis had low germination percentage, both in the wild and in nursery, and did not tolerate seed storage at low temperature. In nursery, diaspores with removed mesocarp of E. paniculata presented greater germination than those in entire fruits. The high levels of seedling mortality beneath mother-trees of C. moschata, when in comparison to those observed to established seedlings from diaspores dispersed by muriquis (Brachyteles arachnoides E. Geoffroy 1806, Cebidae, Primates), allied to the absence of juveniles in the understory, are in accord with the escape model of Janzen-Connel. In nursery, diaspores of C. moschata dispersed by the primates had greater germination, in smaller time, than those collected from mother-trees.

THE EVOLUTIVE SIGNIFICANCE OF POLLEN USE AS PROTEIN RESOURCE BY TRIGONINI BEES (HYMENOPTERA, APIDAE, MELIPONINAE)

The origin of bees was marked by the change from the use of animal of vegetal protein to feed the larvae. The advantages of this change and the existence of some necrophagous species among the bees is discussed regarding to the poor digestibility of pollen.

Effect of fruit maturation stage and light on seed germination of Aiphanes aculeata

Despite their spiny nature, Aiphanes palms are popular as ornamentals. They can be grown in various soil conditions, but achieve fast, luxuriant growth in sheltered positions with plenty of water. Shaded conditions are the best when plants are young. The objective of this study was to evaluate the effect of fruit maturation stage and light on the germination of seeds of A. aculeata. Fruits were collected at three different maturation stages: (1) yellow, (2) red, (3) collected on the ground without the fleshy mesocarp (removed by birds and insects). The fleshy mesocarp was also removed in treatments (1) and (2). All fruits were then treated with thiram and 25 seeds per plot were seeded in trays full of sand. The treatments (2) and (3) were subdivided in two other treatments: (a) 12 h photoperiod, (b) continuous darkness. The temperature was maintained at 30 degrees C. Seed germination began 34 days after sowing. After 160 days, the final germination percentage was (1) 54,67%, (2a) 61,33%, (2b) 65,33%, (3a) 38,00% and (3b) 45,33%. The best treatment was (2) independently of the light conditions.

Weed seed-germination .3. bidens-pilosa L

The germination of seeds of Bidens pilosa L. colected at different places was analyzed by dose-response curves for induction and reversion of germination in seeds pre-incubated at 25 degrees C or 36 degrees C during 24 hours. Our results indicate that phytochrome is responsible for the control of seed germination id Bidens pilosa and the level of pre-existing active form of phytochrome (Pfr) above the threshold switch the seed to germinate in darkness.

IN-VITRO INHIBITION OF SPORES GERMINATION OF ALTERNARIA-SOLANI BY 3 FUNGICIDES

In vitro inhibition of the of spores germination of Alternaria solani by iprodione, chlorothalonil, and anilazine at different dosages was studied. The highest concentration of active ingredient studied for each fungicide was equivalent to that recommended for the control of the early blight, under field conditions: 0.75; 1.80 and 1.44 g, respectively, of iprodione, chlorothalonil and anilazine per litre of water. A series of two-fold diluitions of each original concentration was studied in additional nine experiments. Eah of the three fungicides showed total in vitro spore inhibition at the highest rate, at six hours of incubation. At nine hours, only analazine mantained its full inhibition activity. The inhibition activity of iprodione decreased suddenly after 1/2 dilution, so that at the 1/8 dilution a total loss of inhibitory activity was observed. Chlorothalonil showed a progressive and slighter decrease of its activity as the dilution rate increased.Analizine showed a high inhibitory activity at higher dilutions, without any loss up to 1/128 dilution. Even at 1/512 dilution, its activity was so high that only 20% of spore germination was observed at six or nine hours of incubation.

Analysis of seed-germination in Piptadenia-Gonoacantha (Mart) MACBR (Leguminosae Mimosoideae)

Preliminary tests indicated 20-degrees-25-degrees-C as optimum temperature range to the germination of the seeds of P. gonoacantha. Seeds germinate both under light and dark conditions, although final percentage is always higher in latest condition. The transmission spectrum of the tegument was investigated and showed an enrichment of the light in far-red region which reaches the embryo. Consequently the white light inhibits partially germination. Another factor controlling germination was the water availability. Our results indicated that the excessive water available during imbibition inhibits the germination process. According to our results we propose that this species do not have a pioneer behavior and even though P. gonoacantha had been described as a riparian vegetation species, the germination process is strongly inhibited with excessive water during imbiibition process.

Effect of pre-imbibition and osmoconditioning on seed-germination in Phaseolus-vulgaris L. under water-stress

The effect of osmoconditioning and controlled water sowing was analysed in seeds of Phaseolus vulgaris L. cv. carioca on germination under water stress conditions. The pre-sowing in water at low temperature to limit germination resulted in the increase in the tolerance to water stress. The osmoconditioning with PEG for 48 hours increased the tolerance of bean seeds to water stress of -0.51MPa. The osmoconditioning or controlled water sowing can be used as a practice to increase the tolerance of bean seeds to water stress before planting in the field.

Effects of plant regulators and potassium nitrate, on Rangpur lime seeds germination

The effects of plant regulators and potassium nitrate were studied on 'Rangpur' lime (Citrus limonia Osbeck) seeds germination. The seeds were removed from ripe fruits, washed, dried and stored at 4 - 5 degrees C, and treated for 24 hours before sowing and the treatments were: KNO3 0,1% and 0,2%; GA(3) 50 ppm, 100 ppm and 250 ppm; GA(4+7)+phenylmethylaminepurine 100 ppm; phenylmethylaminepurine 20 ppm and control. The germination was evaluated begining 13 days after sowing. Best results were obtained with KNO3 0,2%, which proved most beneficial in enhancing percentage and germination rate.

Study of spore germination in Thelypteris-dentata (forssk) e-st-john

The spore germination in Thelypteris dentata was studied and the optimum temperature of 25 C was determined by the maximum percentage germination and the highest germination index. The necessity of continuous white light irradiation and reversion of spore germination by subsequent far-red light irradiation indicate the involvement of phytochrome in the control of the process. The dependence of induction of spore germination to the continuous white light low irradiance confirms the phytochrome control through the low fluence response.