Flowering is essential in any breeding programme, particularly in genetic introgression programmes in which flowering synchronism is required. In this work, 16 sugarcane genotypes were evaluated using three different flowering-inductive photoperiod treatments (30 s, 45 s, and 1 min of a daily photoperiod decrease from 12 h 55 of light). Each genotype was planted in 43 L pots (equal proportion of soil, sand, and substrate) with three tillers per pot. Plants with 4 to 6 internodes were placed in a photoperiod facility with three controlled chambers, each chamber containing all 16 genotypes (one treatment per chamber). The temperature range (21˚C to 32˚C) and humidity were the same for all of the treatments. The flower induction started in September 2010 and ended in April 2011. The plant elongation and flag leaf and inflorescence emergence were recorded and the pollen viability was evaluated by using the iodine staining method. The photoperiod facility provided suitable conditions for flowering, as the plants in the three treatments successfully flowered. The genotypes in the three treatments behaved differently in relation to the date of panicle emergence, with the treatment of 45 s showing better results. The results here presented contribute to synchronise flowering for desired sugarcane crosses, particularly those from introgression programmes between commercial cultivars and species from the Saccharum complex.

ABSTRACT. The self-fertilization or selfing rate estimation using microsatellite markers and its impact on survival and selection rate were evaluated in families derived from polycrosses that involved parents that were widely used in sugarcane breeding in Brazil. These factors were evaluated under unfavorable natural conditions of flowering and crossing. After the germination test, the viable progeny were taken to the field for survival rate evaluation (4, 6, and 10 months) and phenotypic selection at plant cane. The selfing rate estimate based on microsatellite markers present in the progeny and absent in their female parent was 98.5 and 0% for the polycross families derived from IACSP95-5000 and SP89-1115, respectively. The survival and selection rates in the last 2 evaluations were higher for the SP89-1115 outcrossed family than the IACSP95-5000 selfed family. The IACSP95-5000 cultivar excelled either as pollen donor with fertilization capability or viable seed production even under unfavorable natural conditions of crossing. The Selfing rate in sugarcane environment influence (temperature and humidity) had an important role during the polycross.

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RESUMO -Objetivou-se nesse estudo avaliar o papel atenuador da espermidina exógena sobre a germinação, vigor de sementes e crescimento de plântulas de cultivares das forrageiras alfafa, guandu e labe-labe submetidas ao estresse salino. A semeadura foi realizada em caixas de plástico tipo "gerbox" forradas com papel de filtro umedecidos com soluções salinas nas concentrações de 0, 20, 40, 60, 80 e 120 mM de NaCl contendo 0 ou 0,5 mM de espermidina. O delineamento experimental foi inteiramente casualizado em esquema fatorial 3 x 6 x 2 (forrageiras x salinidade x espermidina) com cinco repetições de 25 sementes. As avaliações da germinação foram realizadas no quarto e décimo dias, juntamente com o índice de velocidade de germinação (IVG), avaliado até o nono dia após a semeadura. Determinou-se a concentração salina que reduz em 50% a germinação e a massa seca da parte aérea e raiz no décimo dia após a semeadura. A aplicação de espermidina exógena proporcionou maior acúmulo de massa seca das raízes de labe-labe cv. Rongai, além de ter possibilitado a germinação de 50% das sementes de guandu cv. Caqui até a concentração salina de 72,09 mM de NaCl, assim como maior IVG nas sementes das leguminosas alfafa cv. Crioula e labe-labe cv. Rongai. Exogenous spermidine alleviates the effects of NaCl on the germination and initial growth of forage legumes ABSTRACT -The objective of this study was to evaluate the mitigating role of exogenous spermidine on the seed germination, seed vigor and seedling growth of alfalfa forage cultivars, pigeon pea and lablab subjected to salt stress. The seeds were sown in plastic gerboxes lined with filter paper moistened with saline solutions at concentrations of 0, 20, 40, 60, 80 and 120 mM NaCl containing 0 or 0.5 mM spermidine. The experimental design was a completely randomized factorial 3 x 6 x 2 (forage x salinity x spermidine) with five replicates of 25 seeds. Germination was evaluated on the fourth and tenth days, along with the germination speed index, measured until the ninth day after sowing. The salt concentration had reduced germination and the dry weight of shoot and root by 50% on the tenth day after sowing. The application of exogenous spermidine resulted in a greater dry root weight of lablab cv. Rongai, 50% germination of pigeon pea seeds cv. Caqui at the salt concentration of 72.09 mM NaCl, and a higher GSI for alfalfa cv. Crioula and lablab cv. Rongai seeds.

Commercial sugarcane cultivars and wild species have a high ploidy level allied to a complex genome and usual chromosomal instability. There are few studies related to the standardization of cytogenetic techniques in sugarcane. This work tested the efficiency of three antimitotics (colchicine, 8-hydroxyquinoline, and trifuralin) at different concentrations on the quality of metaphases spreads from a commercial sugarcane cultivar (IAC911099-Saccharum spp.) and a wild sugarcane accession (Krakatau-S. spontaneum). Although all three antimitotics were efficient for obtaining metaphases, 8-hydroxyquinoline was the most efficient for both IAC911099 and Krakatau. The chromosome number of these two genotypes was inferred. The variation in chromosome number was 2n = 90-112 for IAC911099, with a statistical modal of 2n = 112 chromosomes while the variation in chromosome number was 2n = 90-129 chromosome with a statistical modal of 2n = 128 chromosomes for Krakatau (S. spontaneum).