Temperature and Light Requirements for the Sprouting of Chilled and Unchilled Tubers of the Purple Nutsedge, Cyperus rotundus

Abstract

Mature and immature tubers of purple nutsedge (Cyperus rotundus L.) chilled at 0°C in dry and wet conditions, were sprouted along with fresh, unchilled tubers over a range of temperatures (1O°C-45°C) in light and darkness. Fresh immature tubers showed a high sprouting percentage at all temperatures between 20°C and 40°C, while the mature ones did so only at 30°C and 35°C. Chilling of dry tubers stimulated early sprouting and increased the maximum sprouting percentage of both the mature and immature tubers. Dry chilling also lowered the limit of favourable temperatures to 15°C in the case of mature tubers. Chilling of wet tubers had a depressing effect and no sprouting occurred below 30°C. At all temperatures, light apparently favoured the sprouting of both the mature and immature tubers (except mature wet-chilled ones at 35°C and 40°C). Immature tubers showed relatively higher sprouting percentage than the mature ones, both in light and darkness. Alteration of temperature requirements due to dry and wet chilling of the tubers is regarded as significant and functional in relation to the ecology of the species.

Purple nutsedge tuber sprouting

“…In studies using tubers separated from the rhizome chains, Shamsi et al (1978) compared the sprouting of immature and mature tubers at a wide range of constant temperature conditions. More immature tubers sprouted than mature tubers, with the greatest difference in sprouting occurring at suboptimal temperatures; 100% of the immature tubers sprouted at constant temperatures ranging from 20 to 35°C, while only 10–60% of mature tubers sprouted at 20°C, depending upon whether tubers were incubated in the light or dark, and different chilling conditions.…”

Effect of vitamins on sprouting of purple nutsedge tubers

“…In all treatments 2-3 sprouts were initiated within 10 days. For KIN a somewhat similar count, based on the number of sprouts per replicate of 10 tubers, was reported by Tao et al (1973). It appears that sprout initiation is the innate capacity of the tubers and is thus insensitive to any treatment.…”

Efeito da palha de cana-de-açúcar e do tamanho de tubérculos no desenvolvimento da tiririca (Cyperus rotundus L.).

“…Shamsi et al (1978) e Holt & Orcutt (1996 determinaram o limiar térmico para a tiririca nas condições americanas. Eles observaram que os limites superior e inferior são, respectivamente, 40 e 10 ºC.…”

“…Estudos têm mostrado que a faixa de temperatura ótima para que ocorra brotação é de 25 a 35 º C (Shamsi et al, 1978) sendo a máxima e a mínima, respectivamente, 45 e 13 º C (Miles et al, 1996). Miles et al (1996) compararam a resposta da tiririca à temperatura constante e alternada e determinaram o efeito da amplitude da oscilação térmica e o tempo de exposição à temperatura máxima.…”

“…Estudos realizados por Shamsi et al (1978) mostraram que a temperatura ótima para a brotação da tiririca é de 25 a 35 º C, sendo a mínima e a máxima, respectivamente, de 10 e 40 º C (Miles et al, 1996). A adição de palha de cana-deaçúcar, dependendo da quantidade, afeta a amplitude térmica da camada de solo onde ficam situados a maioria dos tubérculos de tiririca podendo reduzir sua brotação.…”