Fruit quality and leaf photosynthesis in response to microenvironment modification around individual fruit by covering the fruit with plastic in nectarine and peach trees

The effects of covering fruit with clear plastic film during the final stage of rapid fruit growth were investigated on 'Big Top' nectarine and 'Opal' peach over three years. Covering fruit with plastic film modified the microenvironment around the fruit, particularly by increasing relative humidity and temperature during the day. These modifications influenced fruit development, fruit quality and leaf photosynthesis. Covering fruit with plastic film significantly reduced the dry matter content, either for fruit flesh or for total fruit, the content of total soluble solids in fruit fresh, and leaf photosynthesis under high light intensities (photosynthetically active radiation in excess of 1000 mu mol m(-2) s(-1)) as compared with uncovered control fruit. The relationship between photosynthetic rate and other leaf physiological responses showed that the depression of photosynthetic CO2 assimilation was related to reduced stomatal aperture and increased leaf temperature. It is suggested that the stomatal aperture may be considered as the trigger or promoter and leaf temperature as the regulator of photosynthesis under a lower sink-source ratio.