Effects of post-harvest water stress on autumnal bloom and subsequent-season productivity in mid-season ‘Spadona’ pear

SummaryThe effects of post-harvest water stress on the productivity of ‘Spadona’ pear in the subsequent season and on autumnal bloom were studied in field-grown mid-season pear. Two factors were examined in the post-harvest period: the degree of post-harvest water stress, and the effect of application of a significant amount of water at the beginning of October (to simulate water stress-relief by autumnal rain). Three post-harvest irrigation regimes were applied to establish three thresholds of post-harvest midday stem water potential: High (approx. –1.5 MPa), Medium (approx. –2.5 MPa), and Low (approx. –2.8 MPa). Subsequent-season productivity in both the High and the Low treatments was lower than in the Medium treatment. A significant autumnal bloom occurred in response to the Low treatment, followed by a rapid and significant increase in midday stem water potential after the application of 50 or 60 mm of irrigation at the beginning of October. The Low treatment, plus 50 or 60 mm of irrigation at the beginning of October, resulted in the lowest subsequent-season crop yield, indicating that autumnal bloom decreased subsequent-season bloom. The low level of autumnal bloom that occurred in response to the Medium treatment, followed by 60 mm of irrigation at the beginning of October, did not affect subsequent-season productivity but increased the susceptibility to infection by fire-blight. Therefore, a threshold level of post-harvest midday stem water potential of –2.2 MPa is suggested as a way to avoid both autumnal bloom and a reduction in productivity in the subsequent season.