A B S T R A C TThe objective of this study was to determine the desorption isotherms of 'cajuzinho-docerrado' achenes (Anacardium humile St. Hil.) in various conditions of temperature and water activity, as well as to select the one that best represents the phenomenon and to determine the isosteric heat of desorption. The fruits were collected at the Emas National Park, in the municipality of Mineiros-GO, Brazil, pulped and then subjected to drying in silica gel at temperature of 25 ± 2 °C until the moisture contents of 17.6, 13.6, 11.1, 8.7 and 5.3 (d.b.%). After drying, the desorption isotherms were determined by the indirect static method. The water activity (Aw) was determined at different temperatures, and the achenes were placed in a B.O.D. chamber, regulated at 10, 20, 30 and 40 °C. Data of hygroscopic equilibrium moisture content were fitted to different mathematical models through nonlinear regression analysis, using the Gauss-Newton method. The Copace model was the one that best represented the hygroscopicity of 'cajuzinho-do-cerrado' achenes, while the integral isosteric heat of desorption of 'cajuzinho-do-cerrado' achenes for the moisture content range of 4.51 to 13.40 (% d.b.) varied from 2,734.82 to 2,548.49 kJ kg -1 . Isotermas de dessorção e calor isostérico de aquênios de cajuzinho-do-cerrado R E S U M OObjetivou-se, com este trabalho, determinar as isotermas de dessorção de aquênios de cajuzinho-do-cerrado (Anacardium humile St. Hil.) em diversas condições de temperatura e atividades de água e selecionar aquela que melhor representa o fenômeno e determinar o calor isostérico de dessorção. Os frutos foram coletados no Parque Nacional das Emas, no município de Mineiros -GO, despolpados e em seguida submetidos à secagem em sílica gel a temperatura de 25 ± 2 °C, até atingirem os teores de água de 17,6; 13,6; 11,1; 8,7; 5,3 (% b.s). Após a secagem foram determinadas as isotermas de dessorção pelo método estático indireto. A atividade de água (Aw) foi determinada sob diferentes temperaturas sendo os aquênios acondicionados em câmara B.O.D., regulada a 10, 20, 30 e 40 °C; aos dados de teor de água de equilíbrio foram ajustados a diferentes modelos matemáticos por meio da análise de regressão não linear, pelo método Gauss-Newton. O modelo Copace foi o que melhor representou a higroscopicidade dos aquênios de cajuzinho-do-cerrado enquanto os valores de calor isostérico integral de dessorção dos aquênios de cajuzinho-do-cerrado para a faixa de teor de água de 4,51 a 13,40 (% b.s.) variaram de 2734,82 a 2548,49 kJ kg -1 .

The objective of this study was to evaluate different pre-germination treatments, histochemical characteristics and physiological performance of Sapindus saponaria L. seeds as a function of temperature and the germination substrate. The S. saponaria seeds were collected in the municipality of Rio Verde, GO, and analysed through the execution of 2 tests (dormancy breakage and germination tests). Test 1 consisted of 10 treatments for overcoming dormancy, whereas test 2 consisted of a 35-day evaluation of germination on several substrates (paper and sand) under the following 4 temperature conditions: 20, 25, 30°C and alternating 20-30°C (± 0.5°C). The results of the dormancy breakage and germination tests were submitted to analysis of variance (ANOVA), and the means were compared by the Tukey test. Scarifying S. saponaria seeds with concentrated sulfuric acid for 90 min provided a relatively high speed and percentage of emergence, without causing anatomical damage. Pre-germination treatments using high- (42 °C) or low-(10 °C) temperature stress caused cellular damage in the endosperm region of S. saponaria seeds. The greatest percentage of S. saponaria seeds germinated on a paper substrate at 30°C.

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The present study aimed to evaluate the possibility of using cryopreservation method for conservation of cajuzinho-do-cerrado achene (Anacardium humile). To accomplish this aim, the physiological quality of cryopreserved achenes was compared with the quality of samples stored under other conditions. The quality of cryopreserved achenes with different water contents was also evaluated to establish a water-content limit for seed-viability maintenance. Achenes with physiological maturity were stored in liquid nitrogen at -196 °C with the following water contents: 28 (initial content) 14, 12, 8 and 5% moisture content (m c ). Subsequently, the achenes were subjected to 3 thawing methods: slow/gradual, fast and microwave thawing. Achenes were also subjected to different six conservation methods: cryopreservation in liquid nitrogen (LN) at -196 °C, cryopreservation using 10% cryoprotectants (Dimethyl sulfoxide (DMSO) or Glycerol), 10 °C biochemical oxygen demand (BOD) incubator, -80 °C ultra-low freezer and room temperature (25 °C ±3), with testing after storage in these environments for 5 and 10 months. The treatment effect on achene, physiological quality was assessed by seed germination (percentage) and vigour (germination speed index, electrical conductivity and root and shoot length). The results showed that reduction in the water content considerably reduced the germinating potential of Anacardium humile achenes for cryopreservation. Conversely, the thawing methods had no effect on the physiological quality of cryopreserved achenes; thereby, allowing the choice of the most practical thawing method (microwave). We also concluded that cryopreservation in liquid nitrogen may be used as a viable alternative for conservation of Anacardium humile achene.