Germination of cotton seed in relation to temperature

Abstract

-The effect of constant temperature on the germination rate and percentage of two cotton seed lots was determined using a thermogradient plate. A gradient of 10 ºC to 40 ºC was established across the plate so that temperatures changed 2 ºC for each 5 cm increment in length, resulting in sixteen different temperature treatments. The optimal temperature zone for germination was 28 ºC to 30 ºC. As temperature decreased from the optimal zone, the rate of germination also decreased but germination percentages during the 10-day period were significantly lower only below 20 ºC. As temperature increased above the optimal zone, the rate of germination decreased and the percentage of germination sharply decreased above 32 ºC -34 ºC. As expected, high quality cotton seed performed better than medium quality seed for a low temperature range (16 ºC to 22 ºC), but the most intriguing results were observed for the high temperatures range (36 ºC to38 ºC). The germination of medium quality cotton seed was consistently higher than for high quality seed, especially at 38 ºC after the second day of evaluation. This response has not been reported in the literature and further research is needed to better understand the germination physiology of cotton seed at high temperatures.Index terms: Gossypium hirsutum, thermogradient plate, temperature range.GERMINAÇÃO DA SEMENTE DE ALGODÃO EM RELAÇÃO À TEMPERATURA RESUMO -O efeito da temperatura constante na velocidade e na porcentagem de germinação de sementes de algodão oriundas de dois lotes foi determinada usando a mesa termogradiente. Um gradiente de 10 ºC a 40 ºC foi estabelecido ao longo da mesa de forma que a temperatura mudava em 2 ºC a cada 5 cm de incremento no comprimento entre elas, resultando em 16 tratamentos de temperaturas. A zona de temperaturas ótimas para a germinação foi determinada entre 28 ºC a 30 ºC. Com o decréscimo da temperatura abaixo da zona ótima a velocidade de germinação reduziu, mas a porcentagem obtida no período de 10 dias de avaliação foi significantemente reduzida apenas abaixo de 20 ºC. Com a temperatura aumentando acima da zona ótima a velocidade de germinação reduziu e a porcentagem foi drasticamente reduzida acima da faixa 32 ºC -34 ºC. Semente de algodão de alta qualidade tem desempenho fisiológico ótimo na faixa de baixa temperatura (16 ºC a 22 ºC) em relação as sementes de qualidade média como esperado, mas o resultado mais intrigante foi observado na faixa de alta temperatura (36 ºC a 38 ºC). As sementes classificadas como de qualidade média germinaram consistente em maior porcentagem do que as de alta qualidade, especialmente a 38 ºC após o segundo dia de avaliação. Resultados como este não têm sido reportados na literatura e futuras pesquisas devem ser realizadas para um entendimento melhor da fisiologia de germinação da semente de algodão em alta temperatura.Termos de indexação: Gossypium hirsutum, placa de termogradiente, faixa de temperatura.

Identification of novel sources of genetic variation for the improvement of cold germination ability in upland cotton (Gossypium hirsutum)

“…Consistent with the empirically established effects of low temperature on the germination of cotton seeds (Krzyzanowski and Delouche 2011;Khetran et al 2015;Cole and Wheeler 1974), the experimental materials recorded a general reduction in the overall germination, expressed in terms of mean GP, MGT, MDG, PV and GI, concomitant to decreasing temperatures from 30 to 12°C (Table 4). The FA mutants recorded significantly higher mean values for GP, MDG, and GI at all temperature treatments, resulting in a higher, faster and a more uniform germination compared to both GDRS cultivars and landraces.…”

“…Decrease in temperature below 15°C concomitantly reduces germination percentage and induces chilling injuries that often leads to seedling malformations, taproot loss, reduced vigor, increased occurrence of seedling diseases, poor stand establishment and ultimately, reduced yields. Similarly, low temperature stress at the later stages of growth negatively impacts the crop by delaying fiber elongation and reducing cell wall thickening, resulting in low cellulose production and overall decline in crop productivity (Kittock et al 1986;Speed et al 1996;Krzyzanowski and Delouche 2011).…”

Extreme Temperature Responses, Oxidative Stress and Antioxidant Defense in Plants

“…The maximum seed germination, vigor index occurred at 20-30°C and these temperature regimes were identified as optimum for wheat seed germination. The delay in germination percentage and the reduced germination percentages were observed in Gossypium hirsutum at LT below 20°C [105]. In T. aestivum, the germination is drastically hampered at temperature below 8-10°C [106].…”

Monitor Cotton Budding Using SVM and UAV Images

“…According to the experiments on cotton germination, the germination rate can reach 90% in the laboratory [29]. The mean germination rate of this field study was 56.26%, as presented in Section 4, indicated that the study field has a low germination rate.…”