Crescimento vegetativo sazonal do cafeeiro e sua relação com fotoperíodo, frutificação, resistência estomática e fotossíntese

Abstract

Resumo -O objetivo deste trabalho foi avaliar as flutuações sazonais do crescimento vegetativo do cafeeiro (Coffea arabica L.) e suas relações com o fotoperíodo, a remoção dos frutos, a fotossíntese e a resistência estomática. Os tratamentos foram constituídos por dois regimes fotoperiódicos -natural e estendido para 14 horas -em plantas com frutos e sem frutos. O crescimento de ramos e da área foliar decresceu a partir de meados de março, atingindo taxas mínimas nos meses de maio e junho, quando foram registradas as menores temperaturas. Esse modelo de crescimento não foi modificado pela extensão do fotoperíodo para 14 horas, nem pela remoção dos frutos, ainda que os cafeeiros sem frutos exibissem maiores taxas de crescimento dessas variáveis (ramo e área foliar). Não foi observada diferença significativa na fotossíntese potencial decorrente da presença de frutos, nem a extensão do fotoperíodo afetou taxas fotossintéticas. As taxas fotossintéticas potenciais não explicam os declínios do crescimento vegetativo, mas a temperatura mínima do ar correlacionou-se com as quedas do crescimento. A resistência estomática às 14h apresentou valores relativamente elevados, de meados de março a início de maio, coincidindo com elevadas quedas no crescimento de ramos e da área foliar. O declínio inicial no crescimento vegetativo pode estar associado a temperaturas em torno de 14ºC.Termos para indexação: Coffea arabica, temperatura, curva de crescimento. Seasonal vegetative growth of the coffee plant and its relationship with the photoperiod, fructification, stomatic resistance and photosynthesisAbstract -The objective of this work was to evaluate seasonal variations in vegetative growth in the coffee plant (Coffea arabica L.), as well as their relationships with photoperiod, fruits removal, photosynthesis and stomatic resistance. The growth of the branches and leaf area decreased from the middle of March on, reaching the lowest rates in May and June, when lowest air temperatures were registered. This growth model was not modified neither by extending the photoperiod up to 14 hours, nor by the removal of the fruits, even though fruitless coffee plants exhibited higher growth rates for branches and leaf areas. No significant difference was observed in the potential photosynthesis depending on the presence of fruits, and the extension of the photoperiod did not affect photosynthetic rates. Potential photosynthetic rates do not explain the decreases in growth. The minimum air temperature was associated to declines in the growth. At 14h, the stomatic resistance assumed relatively high values during the period from the middle of March to the beginning of May, so coinciding with drastic fall in the branch growth and leaf area gain. The initial decline in the vegetative growth can be associated to temperatures around 14ºC.

<b>Vegetative growth of Conilon coffee plants under two water conditions in the Atlantic region of Bahia State, Brazil

“…Therefore, the fruiting branches did not lose their growth potential, reinforcing the fact that reproductive growth limits vegetative growth. In fact, Amaral, Rena and Amaral (2006) demonstrated that the growth rate of plagiotropic branches of C. Arabica decreased during a period from the end of summer to the end of autumn, for both bearing and non-bearing branches. Nevertheless, these authors also demonstrated that the net growth rates were always higher for the defruited branches.…”

Crescimento vegetativo de Coffea arabica L. influenciado por irrigação e fatores climáticos no Cerrado Goiano

“…Nazareno et al MAESTRI, 1986). Vários estudos relataram que o cafeeiro apresenta decréscimo acentuado na taxa de crescimento dos ramos nos meses com baixas temperaturas (LIBARDI; AMARAL; AMARAL, 1998;AMARAL, 2006;NAZARENO et al, 2003;SILVA et al, 2004;PARTELLI et al, 2009). …”

Seasonal vegetative growth of different age branches of Conilon coffee tree

“…It has been observed that for latitudes higher than 15 ºS, the greatest vegetative growth occurs with longer and warmer days, as well as with higher precipitation, whereas the lower vegetative growth rates were observed in the colder months with shorter days LIBARDI;AMARAL, 1998;NAZARENO et al, 2003;SILVA et al, 2004). Such decay in the growth rate is not related to photoperiod AMARAL, 2006) or with the presence of fruits in the branches, although the branches without fruits may present higher rates (LIBARDI; AMARAL; AMARAL, 1998; AMARAL; RENA; AMARAL, 2006). It has been reported that the C. arabica low growth phase seems to occur at field temperatures lower than 14ºC (AMARAL; RENA; AMARAL, 2006), which could be related to minimum air temperatures.…”