R. F. Marques

Salt stress on seeds germination and seedlings development of niger (Guizotia abyssinica (L.f.) Cass.)

The soil, and subterranean and superficial water saltiness process is one of the most important environment degradation problems. Niger is an annual herbaceous with biodiesel production potential, which seeds behavior is unknown in saline conditions. In this way, this work aimed to evaluate the niger seeds germination and initial seedlings growth submitted to different salt solutions. The treatments used constituted of three types of salts: NaCl, KCl and CaCl2 at four osmotic potentials (-0.3; -0.6; -0.9 e -1.2 MPa). The niger seeds sowed directly on substrate water moistured constituted the control treatment. The saline effects on seeds germination were evaluated though germination percentage, germination medium time and germination speed index. The Niger seedlings were analyzed through the shoot and root length and fresh and dried mass seedlings. The statistic design used was entirely casualized, constituted by a factorial 3x5 (salts x osmotic potentials) with four repetitions of 50 seeds. The Niger seeds are salinity sensitive. Seeds exposition to NaCl, KCl and CaCl2 reduces the germinative ability and the seedlings growth at -0.3 MPa. The salt solutions inhibit the Niger seeds germination at -1.2 MPa.

Germinação, biometria de sementes e morfologia de plântulas de Guizotia abyssinica Cass

The niger plant (Guizotia abyssinica Cass.) is a herbaceous annual with a potential for biodiesel production but information on seed quality is scarce. The objective of this study was to determine the temperatures and substrates for seed germination and initial seedling development, besides characterizing niger seed and seedling morphology. One thousand seed weight, moisture content, weight, length, width and thickness of seeds were determined. The seed germination test was done at a constant temperature in continuous light (15 °C, 20 °C, 25 °C and 30 °C) and with an alternating temperature (20-30 °C) with 10 h dark and 14 h of white light for the highest temperature and two substrates (on paper and between paper). The seed imbibitions curves germination percentage, germination speed index, mean germination time, seedling length and dry weight were determinated. The niger seeds had similar dimensions: 4.54 mm long, 1.39 mm wide, 1.15 mm thick and a mean weight of 0.0043 g. The 20-30 °C and 25 °C temperatures and the two substrates tested are suitable for the niger seed germination test.

Emergence and initial growth of Hancornia speciosa (Gomes) seedlings with different substrates and water availability

Hancornia speciosa is a promising fruit species due to the high protein content of its fruit. However, there is little information about its production, with a lack of information concerning the germination of its seeds and initial seedling growth. The aim of this study was to evaluate water availability and suitable substrates for its seedling emergence and production. The seeds were deposited in tubes, containing the following substrates: Distroferric Red Latosol (L); Latosol+Sand (L+A); Latosol+Bioplant® (L+B); Sand+Latosol+Poultry Litter in the following proportions 2:2:1 (L+A+C1) and 2:4:1 (L+A+C2) associated with water retention capacities of 25%, 50%, 75% and 100%. The substrates L+A, L+B and L and a water availability of 75% to 100% are recommendable for seedling emergence and early seedling growth. Substrates that consisted of poultry litter and water availability of 25% and 50% were prejudicial to growth and quality of Hancornia speciosa seedlings.