TY - JOUR
T1 - Drought responses of profile plant-available water and fine-root distributions in apple (Malus pumila Mill.) orchards in a loessial, semi-arid, hilly area of China
AU - Song, Xiaolin
AU - Gao, Xiaodong
AU - Wu, Pute
AU - Zhao, Xining
AU - Zhang, Wei
AU - Zou, Yufeng
AU - Siddique, Kadambot H.M.
PY - 2020/6/25
Y1 - 2020/6/25
N2 - The number of apple (Malus pumila Mill.) orchards has increased substantially in hilly regions of the Loess Plateau of China, as a significant element of the large-scale ‘Grain for Green’ ecological rehabilitation program that aims to conserve soil and water while improving the regions economic prospects. However, the long-term effects of the orchard expansion and the adaptive responses of apple trees to drought are not known. Thus, using a space-for-time substitution approach, we investigated plant-available water and fine-root distribution in the 0–8 m soil profile in apple orchards of various ages in a dry year (2015, 392 mm rainfall) and the following year with normal precipitation (2016, 500 mm rainfall). We found that plant-available water gradually decreased with stand age in the dry year, but increased in the normal year, especially in the 0–2 m soil layer. Fine root (<2 mm diameter) distribution and biomass increased with stand age and decreased with increasing soil depth in all treatment plots, predominantly in the 0–2 m layer. In all treatment plots, most of the soil layers in the deep soil (>2 m) had soil moisture storage deficit. In the dry year (2015), the apple trees increased both the average depth (D50 and D95 values) and biomass of their fine-root systems in response to water stress, relative to the normal year (2016). Thus, the apple trees extracted water primarily from the shallow (<2 m) layers in the normal year, but from deeper soil layers in the dry year, to sustain growth. The results of this study will help to guide land and agricultural water management in rainfed apple orchards in hilly regions of the Loess Plateau and similar dryland regions.
AB - The number of apple (Malus pumila Mill.) orchards has increased substantially in hilly regions of the Loess Plateau of China, as a significant element of the large-scale ‘Grain for Green’ ecological rehabilitation program that aims to conserve soil and water while improving the regions economic prospects. However, the long-term effects of the orchard expansion and the adaptive responses of apple trees to drought are not known. Thus, using a space-for-time substitution approach, we investigated plant-available water and fine-root distribution in the 0–8 m soil profile in apple orchards of various ages in a dry year (2015, 392 mm rainfall) and the following year with normal precipitation (2016, 500 mm rainfall). We found that plant-available water gradually decreased with stand age in the dry year, but increased in the normal year, especially in the 0–2 m soil layer. Fine root (<2 mm diameter) distribution and biomass increased with stand age and decreased with increasing soil depth in all treatment plots, predominantly in the 0–2 m layer. In all treatment plots, most of the soil layers in the deep soil (>2 m) had soil moisture storage deficit. In the dry year (2015), the apple trees increased both the average depth (D50 and D95 values) and biomass of their fine-root systems in response to water stress, relative to the normal year (2016). Thus, the apple trees extracted water primarily from the shallow (<2 m) layers in the normal year, but from deeper soil layers in the dry year, to sustain growth. The results of this study will help to guide land and agricultural water management in rainfed apple orchards in hilly regions of the Loess Plateau and similar dryland regions.
KW - Apple orchards
KW - Loess plateau
KW - Management
KW - Plant-available water
KW - Soil moisture storage deficit
KW - Stand age
UR - http://www.scopus.com/inward/record.url?scp=85081917688&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2020.137739
DO - 10.1016/j.scitotenv.2020.137739
M3 - Article
C2 - 32203796
AN - SCOPUS:85081917688
VL - 723
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
M1 - 137739
ER -