Effects of soil water status on late season shoot and root growth of low chill Asian pears in lowland subtropical Taiwan
Date Issued
2011
Date
2011
Author(s)
Hsiao, Yuan-Shang
Abstract
This research was carried out in Horticulture Research and Experimental Farm, College of Bio-Resources and Agriculture of National Taiwan University from October 8, 2007 to January 3, 2008. We measured shoot and root growth of low chill Asian pears in lowland subtropical Taiwan to document the effect of soil water status on late season shoot and root growth of potted two-year-old ‘Tainung No.2’/Lindley’s pear trees. Trees were irrigated with five irrigation treatments: Control treatment (CK), plants were maintained at 30-45% soil water content; Drought treatment (D), plants were not watered until soil water content below 20% and then irrigated back to 45%; Drought and 3 three-day Flooding (D+3F), plants were not watered until soil water content below 20% and then flooded for 3 days; Moderate Drought and 3 three-day Flooding (LD+3F), plants were not watered until soil water content to 20-30% and then flooded for 3 days; Drought and five-day Flooding (D+5F), plants were not watered until soil water content below 20% and then flooded for 5 days. Mature leaves after D, D+3F and D+5F treatments defoliated sooner than those subjected to CK and LD+3F. During the early period of the experiment, there were two to three peaks of root growth. In January, the vast majority of the new roots turned dark brown or was invisible, leaving on a small portion of survival white and yellow roots. By comparing the five irrigation treatments during the early period of the experiment, soil moisture fluctuation significantly decreased new root survival. New root survival (%) for the five irrigation treatments during the early period were: 89.26±1.21% (CK), 82.95±2.43% (D), 74.14±6.14% (D+3F), 92.28±2.10% (LD+3F), and 68.08±4.30% (D+5F). Overall by analyzing the longevity at when 50% of the new white roots turned yellow and at when 50% of the new roots turned dark brown, black or invisible, we found that plants subjected to CK, D and LD+3F had a higher new root survivorship compared to those subjected to D+3F and D+5F. By analyzing the correlation of canopy mature leaf retention (% of DAT0) versus cohort new roots remaining white (%) in DAFR40, we found that there was a high correlation between these two events. The coefficient of determination, r2, between new roots remaining white and canopy mature leaf retention (% of DAT0), and between new root survival and canopy mature leaf retention (% of DAT0) were 0.5562 and 0.7371, respectively.
Subjects
Autumn roots
New roots
Volunetric soil water content
Mature leaves
SDGs
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