Qualidade fisiológica das sementes de sorgo sacarino submetidas à secagem em diferentes condições de ar

Abstract

R E S U M OObjetivou-se, com este trabalho, analisar a qualidade fisiológica das sementes de sorgo sacarino submetidas à secagem em diferentes condições de ar. A secagem do sorgo sacarino foi realizada mantendo-se as temperaturas controladas de 40, 55, 70, 85 e 100 °C e umidades relativas de 28,4; 18,6; 12,2; 7,3 e 3,1%, durante os períodos de 3,0; 1,75; 1,42; 1,08 e 0,83 h, respectivamente. Depois da secagem as sementes foram submetidas às análises de condutividade elétrica, porcentagem de germinação, primeira contagem da germinação, índice de velocidade de germinação (IVG), porcentagem de emergência, primeira contagem da emergência e índice de velocidade de emergência (IVE). Constata-se que o aumento da temperatura do ar de secagem promove maior danificação nas sementes, pelo aumento da condutividade elétrica da solução. A porcentagem de germinação, IVG, porcentagem de emergência e o IVE, tiveram seus valores reduzidos pelo incremento de temperatura. Conclui-se que a qualidade fisiológica das sementes de sorgo sacarino é afetada pela temperatura do ar de secagem e que as temperaturas mais elevadas promovem maiores danos às sementes podendo ser realizada a secagem até a temperatura do ar de 55 °C. Physiological quality of sweet sorghum seeds dried under different conditions of air A B S T R A C TThe aim of the study was to analyse the physiological quality of sweet sorghum seeds dried at different conditions of air. Drying of sweet sorghum seeds was performed at controlled air temperatures of 40, 55, 70, 85 and 100 °C and relative humidity of 28.4, 18.6, 12.2, 7.3 and 3.1%, during 3.0; 1.75; 1.42; 1.08 e 0.83 h, respectively. The seeds after drying were subjected to analysis of electrical conductivity, germination, first count of germination, germination speed index (GSI), germination percentage, emergence and emergence rate index (ERI). It was found that increasing the temperature of the drying air promotes greater damage to the seeds by increasing the electrical conductivity of the solution. The percentage of germination, GSI, emergence percentage and ERI were reduced with increase in temperature. It is concluded that the seed quality of sweet sorghum is affected by drying air temperature, and that higher temperatures promote greater damage to the seed; drying can be performed until the air temperature of 55 °C. Palavras-chave:danificação germinação vigor

Physiological Maturation in Seeds of Sweet Soghum for Foliar Fertilisation With Silicate

“…In the case of commercial production, artificial drying, which raises the cost of production in regions of high humidity, would not be necessary, a great advantage for seed production in the semi-arid region. Ullmann et al (2015) verified high physiological quality in seeds of sweet sorghum with artificial drying at a temperature of 40ºC. In the present study, in the final month of the crop cycle, the air temperature reached a range of 35ºC to 37ºC (Figure 1), which provided for adequate drying of the seeds while still in the field.…”

“…This range of germination was similar to that found by Ullmann et al (2015), where the seeds of the BRS 506 variety of sweet sorghum reached a value for germination of 88% to 94%, indicating high physiological quality for the different conditions of the study. In a study carried out in Iran with other varieties (Rio, Keller, Sofra and Soave), germination was no greater than 71% in the standard germination test (ALMODARES; HADI; DOSTI, 2007), far less than the results in the present work.…”

The effect of drying temperatures and storage of seeds on the growth of soybean seedlings

“…In this context, Costa et al (1999) highlight that the greater the length of the hypocotyl, the greater the seedling capacity to emerge and overcome the resistance that may be posed by depth of sowing and/or hardened soil. The effect of different drying temperatures on the physiological quality of seeds was also observed by Ullmann et al (2015) in evaluation of sweet sorghum seeds, in which a reduction in the germination was observed in accordance with the temperature factor, especially at temperatures above 40 °C; each increase in degree of temperature led to reduction of half a percentage point in germination. As suggested by Afrakhteh et al (2013) and also observed by Menezes et al (2012a,b), and furthermore in this study, this is generally a result of the increase in the rate of water removal (WRR) from the product, which is stimulated by the increase in temperature of the drying air.…”

Physiological quality of sweet sorghum [Sorghum bicolor (L.) Moench.] seeds in response to planting density in semi-arid region

“…An important aspect of germination in cultivars is that seed quality is only one of the factors for ensuring good productivity, and that in addition, there are other factors that may be directly involved, such as environmental factors, among them water availability, temperature, luminosity and soil fertility. Ullmann et al (2015), working in the Cerrado region, also found high values for germination percentage when analysing the BRS 506 cultivar, achieving averages of 94%.…”