Adjustment of Physiological Characters of Root Systems of Wheat by Soil Moisture, Nitrogen and Phosphorus
Liang Yin-li, Chen Pei-yuan
Chin J Plan Ecolo. 1996, 20 (3):
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In the range of soil relative water contents (SRWC) of 40%～70%, we observed that root growth of wheat got limited, root rate area (RA), root water potential (RΨw), root length (RL) and root dry weight (RDW) reduced obviously, root respiration intensity (Rp) increased, as soil water stress got serious. As SRWC increased RΨw increased obviously, Rp reduced, but RL, RDW and RA showed bellshaped response patterns. The maximum value reached for RDW when SRWC was 55%～62%, for RA when SRWC was 54%～57%, and for RL when SRWC was 55%. It is benefit for root deep growth and RA increase when soil moisture tended to be good. Nitrogen and phosphorus had very striking adjustment action on root physiological characters of wheat. Phosphorus nutrition was able to obviously increase RA, RΨw, RL, RDW, but decreased Rp. Especially, under conditions of serious water stress, the adjustment action was even better for RA, RΨw, Rp and RL. There was an obvious difference between nitrogen and phosphorus in adjustment action on root physiological characters of wheat. Under serious water stress, nitrogen was able to lead to decreasing RΨw, and show negative action. Nitrogen had no obvious action on RΨw under a slight drought: it had remarkable positive adjustment action on RΨw when soil water was enough. Nitrogen nutrition was able to raise Rp remarkably. It is of benefit to RDW to enhance application of nitrogen to soil as SRWC increased. The response of RL to nitrogen was not sensitive. Phosphorus could change water relationship in plant body and raise droughtresistance of wheat under water stress besides it acted as a kind of nutrition to promote root growth and development.