The Physiology of Sugar-Cane. IX.·Factors Affecting Photosynthesis and Sugar Storage

Abstract

SummaryPhotosynthesis in sugar-cane was linearly related to light intensity up to full sunlight when leaf geometry was similar to that of field-grown plants_ Individual leaves orientated at right angles to the incident radiation were saturated at about two-thirds full sunlight irrespective of whether the leaves developed in low or high light intensities.On a short-term basis, the QlO for photosynthesis was 1·1 over the range 8-34°C. Exposure of intact plants to a 17/10°C day and night temperature regime for a prolonged period resulted in cessation of stalk elongation and an initial rise in stored sugar followed by a decline in photosynthetic efficiency, which was slowly reversible when the temperature was raised_ Photosynthetic efficiency appears to be llD.ked to availability of sinks but may also' be altered by metabolic imbalance induced by environmental shock. End product repression of photosynthesis by sugars was not the operative control in detached leaves exposed toJong light treatments.

Ripening and Postharvest Deterioration

“…Waldron et al (1967) showed that photosynthetic efficiency fell at low temperatures (17 • C), and culm growth declined but sucrose content continued to increase. After a period of exposure to low temperature, there was a slow partial recovery in the photosynthetic efficiency (Waldron et al 1967) when the plants were once again exposed to higher temperatures.…”

Climatic effects on sugarcane ripening under the influence of cultivars and crop age

“…Burr et al (1957) observed a reduction of 84 % in the rate of sugarcane photosynthesis when air temperature was reduced from 23.0 to 13.6 °C. Waldron et al (1967) showed that the photosynthetic effi ciency decreased linearly with a decrease in air temperature in the range from 34 to 5 °C. The effects of air temperature on the photosynthesis rate and on the effi ciency of this process are directly related to crop vegetative development (Alexander, 1973).…”

“…For the negative degree day accumulation for sugarcane, temperatures between 0 and 7 °C should not be considered because below 7 °C carbon assimilation is negatively affected, as is the stomatal conductance and the photosynthetic rate, which determine the magnitude of the gas exchange of the following day Beauclair, 2004, 2009). As a result of the reduction on carbon assimilation, there is a decrease on the sucrose translocation to stalks (Waldron et al, 1967;Grantz, 1989), and there is an accumulation of sucrose in the leaf cells in an attempt to decrease the matric potential and the freezing temperature of the tissues.…”

“…In most of the recent studies Lingle (2004), Inman-Bamber et al (2009), Leite et al (2011) and Silva and Caputo (2012) have discussed the effects of chemical agents (ripeners) or the biochemistry of the process rather than the natural variables that infl uence ripening. The main studies on the effects of climate on sugarcane ripening were produced between the 1950s and 1970s (Clements, 1962;Glasziou et al, 1964;Waldron et al, 1967;Alexander and Samuels, 1968;Legendre, 1975). Much of the information produced at that time has not been consolidated and organized in such a way that allows these studies to be used in crop planning and decision-making based on the current conditions of the sugar-ethanol sector in Brazil.…”

Some Photosynthetic Characteristics of Citrus Leaves

“…Temperature effects on photosynthesis appear to be variable. Bierhuizen and Slatyer (1964) showed no significant temperature effect on cotton when temperatures were increased from 30 to 40°C, and Waldron, Glasziou, and Bull (1967) obtained a temperature coefficient of 1 . 1 between 8 and 30°C for sugar-cane.…”