Seed size is an important indicator of physiological quality, since it may affect seed germination and seedling growth, especially under stress conditions. This study aimed to investigate the effects of seed size on germination and initial seedling growth, under salinity and water stress conditions. The treatments were arranged in a completely randomized design, in a 3 × 3 factorial scheme: three seed size classes (small, medium and large) and three stress treatments (control, saline or water stress), with four replicates. Water and salt stresses do not reduce the germination rate of medium and large seeds; however, the germination rate of small seeds is reduced under salt stress conditions. Drought stress drastically reduces the shoot growth of seedlings regardless of seed size, whereas root growth is higher in seedlings from medium and large seeds under water stress conditions. Under non-stressful environments, the use of large seeds is preferable, resulting in more vigorous seedlings with a greater dry matter accumulation. Medium-size seeds are more adapted to adverse environmental conditions and, therefore, should be used under conditions of water shortage and salt excess in the soil at sowing time. Seedlings are more tolerant to salinity than to water stress during the germination stage and initial growth under laboratory conditions.

The economic and scientific interest in Hancornia speciosa Gomes (mangabeira) has increased in recent years, especially due to the commercialization of its fruits and the extraction of natural compounds with high pharmacological potential. This paper aims to determine and correlate the main physical and biometric characteristics of fruits and seeds of mangaba tree, as well as identifying the most appropriate substrate for the seedling emergence test. The following physical and biometric traits were measured in 100 fruits and 100 seeds: longitudinal diameter, transverse diameter, thickness, fresh mass, pulp fresh mass, volume, number of seeds. To identify the best substrate, a completely randomized design with two treatments (substrates) and ten replications of 20 seeds was used. The evaluated substrates were: sand and commercial substrate (Plantmax HT®). The shoot height, root length, stem diameter, total dry mass, and the relation between shoot height and stem diameter were evaluated at 50 days after sowing. Mangaba fruits and seeds showed great variations in their biometric traits, in addition to significant and positive correlation predominant in most characteristics. High fruit pulp yield can be optimized with the selection of plants with fruits show greater fresh mass due to the high degree of association between this characteristic and pulp yield. The use of the commercial substrate resulted in higher shoot height, greater number of leaves, and higher shoot height/stem diameter ratio.

A quality substrate is essential to ensure the proper conditions for the emergence and early development of seedlings. The aim of the present study was to evaluate different proportions of termite mound substrate in the emergence and early development of tomato seedlings. The experiment was performed in a completely randomized design, with five treatments constituted by the substrates, with four replications: T 1 : Washed sand (100%); T 2 : Washed sand (75%) + termite mound material (25%); T 3 : Washed sand (50%) + termite mound material (50%); T 4 : Washed sand (25%) + termite mound material (75%) and T 5 : termite mound material (100%). The Santa Clara cultivar (tomato) of Topseed ® was used. The seeds were distributed in gerbox boxes. Emergence, emergence speed index, shoot height, number of leaves, shoot dry mass, root length and root dry mass of tomato seedlings development were evaluated after 25 days. The use of termite mound substrates is a viable alternative to the emergence and development of tomato seedlings. In general, the substrate of termite mound material (100%) was the most promising in the increment of all variables.

The effects of water and salt stress on rate of germination and seedling growth were investigated under laboratory conditions in 46 soya bean genotypes from Central-West region of Brazil to verify how these stresses may limit crop establishment during the initial growth stage and also to identify the most tolerant genotypes to drought and salinity. Mild water and salt stresses were imposed by seed exposure to-0.20 MPa iso-osmotic solutions with polyethylene glycol-PEG 6000 (119.57 g/L) or NaCl (2.357 g/L) for 12 days at 25°C. The germination percentage, seedling length and seedling dry matter were measured, and then, salt or drought tolerance indexes were calculated.

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The physical and / or allelopathic effects caused by cover crops residue can be used to suppress the emergence and / or reduce weed growth. Based on the effects of mulch on soil surface, the objective of this study was to evaluate the influence of cover crops biomass at different residue amount levels in the emergence and development of Digitaria horizontalis. The experiment was carried out in a greenhouse from May to August, 2014, in a completely randomized design with four replications in (5 × 4) + 1 a factorial scheme, consisting of 5 cover crop species (millet cv. ADR 300 (Pennisetum glaucum), braquiaria (Urochola brizantha), sorghum (Sorghum bicolor), cowpea (Vigna unguiculata) and Crotalaria ocroleuca) and four levels of dry mass of the corresponding plant (3, 6, 9 and 12 t ha -1 ) on soil surface, with another treatment without cover crop (0 t ha -1 ). The analyzed variables were the number of emerged plants, shoot dry mass, leaf area, root dry mass and root volume. Cover crops have proven potential to reduce D. horizontalis in all vegetative stages. The species C. ochroleuca and U. Brizantha showed a greater efficiency in reducing the number of emerged plants with a reduction of 86% and 91%, respectively. Amounts between 3 and 6 t ha -1 of cover crops dry mass have been sufficient to promote significant reduction in emergence and growth of Digitaria horizontalis.

Os substratos orgânicos melhoram o teor de matéria orgânica no solo, a disponibilidade de nutrientes e, consequentemente, tem-se mudas de maior qualidade. O objetivo foi avaliar o desenvolvimento de mudas de Capsicum chinense Jacq em substratos orgânicos. O delineamento experimental utilizado foi blocos ao acaso, com seis tratamentos e quatro repetições. Os tratamentos foram as combinações de ninhos de abelha (NA) e substrato comercial Click® (SC), misturados em proporções em base de percentagem do volume (S1=NA100%SC0%, S2=NA80%SC20%, S3=NA60%SC40%, S4=NA40%SC60%, S5=NA20%SC80% e S6=nA0%SC100%). Sementes comerciais de pimenta biquinho foram utilizadas. A altura de plantas, diâmetro do colo, número de folhas, comprimento da raiz principal, massa seca de raízes (MSR) e parte aérea (MSA), massa seca total, relação MSA/MSR, quociente de robustez e índice de qualidade de Dickson foram avaliados aos 56 dias após o plantio. As maiores qualidades de muda foram observadas nos substratos S1, S2, S3 e S4, contudo, o uso do substrato S1 é o mais recomendado, pois reduz os custos de produção é um material acessível aos produtores.

The effects of substrates formulated with different proportions of decomposed buriti stem (Mauritia flexuosa) and the application of nitrogen fertilizer rates in the production of cagaita (Eugenia dysenterica DC.) seedlings were investigated in this study. The treatments were arranged in a completely randomized design, in a 3 × 5 factorial: three substrates formulated from different proportions of decomposed buriti stem (0, 25 and 50%) with a clay loam soil (Oxisol), and five N fertilizer rates (0; 100; 200; 300 and 400 mg dm-3), with four replicates. At 60 days after emergence, the plant height, stem diameter, leaf area, root length, dry matter accumulation of shoots, roots, and total, shoot:root dry matter ratio (SRR), height:diameter ratio (HDR), and Dickson quality index (DQI) were measured. The substrate containing soil and decomposed buriti stem in the proportion of 3:1 (v:v), in association with the application of N rates from 167 to 190 mg dm-3 is recommended for the production of cagaita seedlings, resulting in positive effects on plant growth and development as reported by higher PH, SRR, and HDR. The application of 154 mg dm-3 of N resulted in higher DQI of the cagaita seedlings.