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Pak. J. Bot., 44(6): 1857-1864, 2012.

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ROOT MORPHOLOGICAL CHARACTERISTICS OF LESPEDEZA DAVURICA (L.) INTERCROPPED WITH BOTHRIOCHLOA ISCHAEMUM (L.) KENG UNDER WATER STRESS AND P APPLICATION CONDITIONS

BING-CHENG XU^1,2,*, FU-RONG NIU¹, DONG-PING DUAN¹, WEI-ZHOU XU¹ AND JIN HUANG^1,2

Abstract: Root morphological traits such as root surface area (RSA), root average diameter (RAD), total root length (TRL), specific root area (SRA) and specific root length (SRL) per plant of Lespedeza davurica L. (a C₃ perennial leguminous subshrub) were investigated, when intercropped with Bothriochloa ischaemum (Linn.) Keng (a C₄ perennial herbaceous grass) in a pot experiment using a replacement series design. The two species were planted in the same pot at density ratios of 12:0, 10:2, 8:4, 6:6, 4:8, 2:10, and 0:12 under three levels of soil moisture 80% ± 5% FC (field capacity), sufficient water level (HW); 60% ± 5% FC, moderate water level (MW) and 40% ± 5% FC, severe low water level (LW) and two levels of P fertilization (no P (-P) and 0.1 g P₂O₅ per kg dry soil (+P)). Phosphorous application increased root biomass (RB) of L. davurica under LW, while decreased the root:shoot ratio (RSR) values. P application strengthened the effect of water deficit on root surface area (RSA). Significant linear regressions were observed between RSA and RB at three water levels without P application. While under P application, significant regression equation was only observed at LW. Significant linear regressions were observed between RSA and total root length (TRL) under both P treatments, irrespective of water treatments. Water level statistically significantly affected the RAD values of L. davurica. P application significantly decreased SRA and SRL under severe water stress. All these suggest that root proliferation of L. davurica was increased due to P application, to compete for limited soil resources and increase nutrient acquisition efficiency under water stress and competitive environment.  

¹State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China

²Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China

*Corresponding author e-mail: Bcxu@ms.iswc.ac.cn