The Sanriku coastal region of Tohoku, Japan, is characterized by large interannual weather fluctuations, which is an important consideration when scheduling crop cultivation. Therefore, we developed a temperature summation model to predict harvesting time for mini cauliflower (Brassica oleracea var. botrytis). The model parameters were determined from the data obtained during field experiments, and the model was designed using 30-year air temperature records from the AMEDAS observatories. The results indicated that interannual variation at the time of harvest was less when the cauliflower seedlings were transplanted from mid-April through August, but it increased when seedlings were transplanted after September, with the time of harvest often being delayed to mid-winter or later, resulting in severe cold damage to the crop. Based on these results, we concluded that outdoor-cultivated mini cauliflower seedlings should be transplanted before early September in the northern coast and mid-September in the southern coast to ensure harvesting before winter. The effects of greenhouse cover were also evaluated, assuming that the air temperature inside the greenhouse was 2°C-4°C higher than that of outdoors, which showed that greenhouse cultivation decreased the variation in the time of harvest, allowing the time of transplanting to be extended by 2-3 weeks.
Molecular and physiological processes during cold acclimation (CA) have been investigated using plants incubated under constant low-temperature conditions. However, to comprehensively characterize CA in the field, the effects of day–night temperature cycles and minute-scale random temperature fluctuations must be clarified. Thus, we developed an experimental system that can maintain diurnal cycles and random temperature fluctuations during CA treatments. On the basis of the temperature changes in the field, three CA conditions were applied: conventional CA at 2°C (con-CA), CA with a 10°C day/2°C night cycle (C-CA), and C-CA with random temperature fluctuations only during the day (FC-CA). Because cold-induced Ca 2+ signals help regulate CA, the effects of Ca 2+ signals during the three CA treatments were examined using Ca 2+ channel blockers (LaCl 3 and ruthenium red). The freezing tolerance of Arabidopsis thaliana was similar after the C-CA and con-CA treatments, but it decreased following the FC-CA treatment. The analysis of transcription factors regulating CA processes indicated CBF/DREB1 expression levels tended to be highest for the con-CA treatment, followed by the FC-CA and C-CA treatments. Moreover, the Ca 2+ signals substantially contributed to the freezing tolerance of the plants that underwent the FC-CA and C-CA treatments, while also considerably modulating gene expression in the FC-CA-treated plants. Furthermore, the Ca 2+ signals enhanced CBF/DREB1 expression during the FC-CA treatment, but the Ca 2+ signals derived from intracellular organelles suppressed the expression of CBF2/DREB1C and CBF3/DREB1A during the C-CA treatment. Thus, diurnal temperature cycles and random temperature fluctuations affect CA through different calcium signals, implying that plants regulate CA by precisely sensing temperature changes in the field.
ISHS Europe-Asia Symposium on Quality Management in Postharvest Systems - Eurasia 2007 EFFECTS OF TIO2 PHOTOCATALYTIC OXIDATION IN THE ROOM ATMOSPHERE AND THE QUALITY OF TOMATO FRUIT DURING STORAGE UNDER A CLOSED SYSTEM
