Popcorn breeding programs in Brazil have emerged but despite some advances there is still a lack of material performance studies specially regard to seed quality, in different agricultural seasons. This research was carried out to estimate the popcorn combining ability from biparental crosses between eight tropical and one temperate lines in two agricultural seasons (2008 and 2009) with regard to eight traits related to seed quality, in addition to three agronomic traits related to popping expansion. Method 4, proposed by Griffing (Model 1), was used to verifying the importance of the dominance effect in the genetic control of the seed quality traits, favouring the identification of superior hybrids through seed tests in the laboratory with low cost. The lines from Zélia and CMS42 were promising in obtaining hybrids with superior seed quality and greater popping expansion. The hybrids Zélia 9 IAC-112, CMS42 9 UEM M2-1, CMS43-1 9 IAC-112 and UEM M2-2 9 Zaeli expressed superior SCA for grain yield, popping expansion and at least two seed quality traits. These hybrids are materials of interest for cultivation in different planting seasons.

RESUMO -A disponibilidade hídrica e o movimento de água para as sementes são importantes para a germinação e emergência das plântulas, sendo estes fatores influenciados pelo potencial hídrico do solo, textura do solo e área de contato solo-semente. Sabendo que a salinidade limita o crescimento de muitas plantas, o objetivo desse trabalho foi avaliar o efeito do estresse hídrico e salino na germinação de sementes e no crescimento de plântulas de três cultivares de milho-pipoca (IAC 112, Zélia e BRS-Angela). As sementes foram semeadas em rolos de papel-toalha embebidos com soluções de cloreto de potássio (KCl), utilizando-se cinco níveis de potencial osmótico: 0,0 (controle); -0,1; -0,3; -0,6 e -0,9MPa. A qualidade fisiológica das sementes foi avaliada por meio da primeira contagem e da contagem final de germinação, do comprimento da raiz primária e da parte aérea das plântulas bem como da biomassa seca das plântulas. Os resultados indicam que a diminuição do potencial osmótico provoca redução no desempenho de sementes de milho-pipoca. Houve comportamento diferenciado das cultivares quanto à tolerância ao estresse provocado pelo KCl. As sementes do cultivar BRS-Angela apresentam melhor germinação e crescimento de plântulas em relação às demais, quando submetidas aos mesmos níveis de potencial osmótico de KCl.Termos para indexação: Zea mays, salinidade, desempenho. GERMINATION OF SEEDS AND SEEDLING GROWTH OF POPCORN CULTIVARS UNDER WATER AND SALINITY STRESSABSTRACT -The water availability and the water movement though the seeds are very important to seed germination and seedlings emergence, and these factors are influenced by soil water potential, soil texture and soil-seed contact surface. Knowing that soil salinity limits the growth of several plants, the purpose of this study was to evaluate the effect of water and salinity stress on seed germination and seedling growth of three popcorn cultivars (IAC 112, Zélia e BRS-Angela). The seeds were sown in germination paper substrate imbibed in potassium chloride (KCl) solutions using five levels of osmotic potential: 0.0 (control); -0.1; -0.3; -0.6 e -0.9MPa. The percentage of normal seedlings at the first and final counting of the germination test, as well as root and shoot length and dry biomass of seedlings were used to evaluate seed physiological quality. The results indicated that the reduction of the osmotic potential reduced the popcorn seed performance. There was a differential behavior between the popcorn cultivars to the salinity stress tolerance promoted by the use of KCl. The seeds of BRS-Angela cultivar showed better germination and seedling growth than the others, when submitted to the same level of KCl osmotic potential.

Effect of plant growth regulator on germination and vigor of soybean seedsPlant growth regulators can enhance growth and development of plants and induce cell division. They can also interfere in seed germination. The objective of this study was to evaluate the physiological quality of seeds treated with a plant growth regulator. Seeds of nine soybean (Glycine max (L.) Merrill) commercial cultivars were treated with four concentrations (400; 500 and 600 mL 100 kg -1 seeds) of the plant growth regulator Stimulate®, in addition to a control treated with distilled water. Tests of seed germination and vigor were carried out: it was calculated the germination percentage (first counting and final counting), percentage of normal seedlings; and speed of germination, length of the primary root and the aerial part and dry weight of seedlings were recorded. The experiment was arranged in a completely randomized design with four treatments and four or five repetitions depending on the test. Increasing doses of the plant growth regulator did not influence the germination and the dry weight of the seeds, however, they can increase the speed of germination depending on the cultivar.

Ten popcorn populations (PR 038, PR 079, RR 046, SC 016, PR 017, BRS ANGELA, SC 002, PR 009, PR 023 and SE 013)

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