Root restriction effects of nectarines grown in a non-arable land greenhouse

Abstract

Arable land is a limited resource in Hexi Corridor; however, the development of the peach industry in this non-arable land requires backfilling soil from the same area of farmland to build a greenhouse. To reduce the soil required for backfilling and to protect the local ecological environment, we conducted a four-year experiment composed of five root volumes at levels of 1440 L, 576 L, 360 L, 225 L and 135 L to assess the minimum root restriction volume that could ensure normal growth of greenhouse nectarines with high fruit production. Analyses were focused on photosynthetic performance, vegetative growth, fruit yield and quality, as well as levels of autotoxins and potential allelochemicals in the rhizosphere soil. Compared to RV1440, stem diameter in RV360, RV225 and RV135 were reduced by 18.8%, 26.4% and 30.4%, respectively; however, RV576 did not show growth differences. RV225 and RV135 decreased fruit yields by 23%. This result was supported through analysis of the daily average photosynthetic rate (PN), which showed that the average daily PN was reduced by 17.3% and 13.2% in RV225 and RV135, respectively. Liquid Chromatography Mass Spectrometry (LC–MS) analysis showed that the concentrations of most of the detected compounds in the rhizosphere significantly increased when the root volume was reduced from 1440 L to 360 L. This effect was comparable to the response of a further reduction in root volume (from 360 L to 135 L) with the exception of autotoxic benzoic acid and its derivatives and several strong allelochemicals, which increased significantly. The results confirmed 360 L as the suitable root volume for greenhouse nectarine production on non-arable land in Hexi Corridor, China.