Purple nutsedge tuber sprouting

Abstract

Purple nutsedge (Cyperus rotundus L.) tubers remain viable for several years and serve as its principal means of survival. The maintenance of high moisture content is essential to tuber survival. Apical dominance influences bud dormancy within a tuber and in a chain of tubers, and dormancy increases with tuber age. Several growth inhibitors were identified in tubers, but their role in tuber dormancy has not been established. Moisture levels in soil must increase to a critical level before sprouting occurs, but excess soil moisture deters sprouting. Oxygen may be a limiting factor for tuber sprouting in waterlogged soils. Although light is not a requirement for sprouting, it has promoted sprouting. Temperature regulates sprouting; no sprouting occured below 10°C and above 45°C. Optimum sprouting occurred between 25 and 35°C when provided with constant temperatures. However, daily alternating temperatures greatly stimulated sprouting. A daily short duration (0.5 h) of high temperature increased sprouting to nearly 100%, whereas less than 50% sprouting occurred without the daily high temperature pulse. Bud break occurred readily for most tubers at 20°C and in nearly 100% of the tubers with a single 0.5 h exposure to a high temperature (35°C) pulse. However, most buds did not elongate if the tuber remained at 20°C. Bud elongation occurred at higher temperatures, and daily alternating temperatures stimulated shoot elongation up to eightfold greater than at the respective mean constant temperatures. Daily soil temperature fluctuation may be a major signal for purple nutsedge emergence, such as when the plant canopy is removed, or when soils are solarized. Future research is needed to determine tuber sprouting for different ecotypes, and on the role of the rhizome chain. Systems to manipulate sprouting may provide new strategies for purple nutsedge management.

Potential effects of diurnally alternating temperatures and solarization on purple nutsedge (Cyperus rotundus) tuber sprouting

“…It propagates almost exclusively by vegetative means (basal bulbs, tubers and rhizomes) and therefore mechanical or hand weeding operations are only partially successful in reducing its competitiveness (Bendixen and Nandihalli, 1987). The fast-growing nature, the high viability and the rapid development of vegetative structures for reproduction explain the aggressiveness of this species, allowing it to survive even under stress conditions (Williams, 1982;Nishimoto, 2001). Moreover, C. rotundus is one of the most common weeds of the secondary succession occurring in abandoned and dry fields of arid environments (El-Sheikh, 2005), while Greece is among the countries with the highest percent winter survival of purple nutsedge (Wills, 1998), resulting to an even more difficult control.…”

Distribuição dos tubérculos de Tiririca (Cyperus rotundus L.) no perfil do solo e suas implicações para a conversão para agricultura orgânica de hortas urbanas

“…Lazo e Ascencio (2010) [13] dizem que a manipulação fisiológica da sombra pode ser usada como prática agronômica para o controle das plantas daninhas, pois a modificação temporal da quantidade e qualidade de luz gera uma composição diferente da flora infestante. Segundo Nashimoto (2001) [14], a tiririca sofre com a sombra de cultivos, entretanto, ela retorna com violência após a cobertura vegetal ser retirada.…”

“…Um fator a mais a ser considerado está no fato de que tubérculos em maiores profundidades, apesar de ocorrerem em pequena quantidade, estão menos sujeitos a estresses, fato que lhes garante maiores chances de sobreviverem por longos períodos e servir para o repovoamento das hortas pela planta infestante [14]. Portanto, observa-se que para o produtor orgânico de hortaliças, o combate à tiririca é uma atividade que deve receber atenção constante, para que não seja necessário ocupar muita mão-de-obra com capina que pode onerar demasiadamente a produção de hortaliças, pois como observado na literatura um único tubérculo remanescente no solo pode reconstruir a população da planta daninha.…”

Efeito de sulfentrazone no sistema integrado palha de cana-de-açúcar, herbicida e vinhaça no desenvolvimento inicial da tiririca (Cyperus rotundus)

“…A brotação da tiririca é regulada pela temperatura. Em solo descoberto, a radiação solar aumenta a flutuação diária da temperatura principalmente próxima à superfície do solo (Rubin & Benjamin, 1984) sendo observado que a brotação dos tubérculos e a elongação das hastes ocorrem mais rapidamente (Nishimoto, 2001). Segundo esse autor, a flutuação térmica diária parece ser um mecanismo fisiológico para que ocorra quebra da dormência e elongação da haste da tiririca.…”