| Because of water resource deficiency in the north-west china, the research of drought-resistance has been becoming one of hot points in plant physiology. Most of the studiesconcentrated on the mechanism of hurt to plant by drought , and the adaption of plant todrought and appraising and evaluating to indexes in drought resistance. Most results about theeffects of nitrogenand phosphorus nutritionon drought-resistance were in field crops. A good turf grass, Dichondra repens had been chosen as material to study the changes indrought-resistance from the sprouting to different growing stages(emerging stage, turfforming stage, vigorously growing stage, growing decline stage) and to study the effects ondrought-resistance indexes in water stress by applying different levels nitrogen (Urea),phosphorus ( Single superphosphat ) fertilizers. This study included two parts: germination experiment in lab and water-fertilizerexperiment in field. In the former, using Zoysia japonica as contrast, with differentconcentration Polyethylene glycol (PEG) 6000 induced drought stress, germinationcharacter-istic of the two grasses had been compared. In the latter, soil water was supplied in threelevels: W1 (60%～70%, water sufficient), W2 (40%～50%, light water stress), and W3(20%～30%, severe water stress). Fertilizers had four levels: zero, low, middle and high.Quantity of N was: 0, 0.24kg/100m2 (24.0kg/hm2), 0.57kg/100m2 (57.0kg /hm2), 0.90kg/100m2 (90kg/hm2), quantity of P2O5 was: 0, 0.90kg/100m2 (90kg /hm2), 1.20kg/ 100m2(120kg/hm2), 1.50kg/100m2 (150kg/ hm2), separately. The results of this experiment as follows : 1.Compared to Zoysia japonica, germination force of Dichondra repens was affected bywater stress, but the germination percentage higher than Zoysia japonica, the sensitive valueof Dichondra repens was -11bar (concentration of PEG), and Zoysia japonica was -7bar.Theresults showed that drought-resistance in emerging of Dichondra repens was stronger thanZoysia japonica. 2.With soil water declining, the rate of turf forming of Dichondra repens was slowerthan that in soil water sufficient, but nearly no influences had been found in light water stress.In severs water stress, P and low N could release the effects to rate of turf forming.0.9kg/100m2 (90.0kg/hm2) was the best for P, 0.24kg/100m2(24.0kg/hm2) was the best for N.Too much N had bad influences onturf forming for Dichondra repens. 3.When soil water sufficient, there were the most leaf relative water content (LRWC) invigorously growing stage, 98.64%; superoxide dismutase (SOD) activity reached the highestin vigorously growing stage, 329.55u/gFW; contents of Malondialdehyde (MDA) were theleast in vigorously growing stage, 0.59%; there were the most proline (Pro) in turf formingstage, 0.0222%; soluble sugar (SS) made the most contents in growing decline stage, 1.5%;root vigorous (RV) was the highest in vigorously growing stage, 15.04μg/gDW·h; contents ofChlorophll (Chl) were the most in vigorously growingstage, 47.95mg/L. 4.When soil water stress, with soil water declining, the changing rules of indexes ofdrought- resistance of Dichondra repens were: LRWC decreased; SOD activity rose in lightwater stress, declined in severs water stress; Contents of MDA, Pro and SS increased; RVdeclined; Chl contents decreased. The changes of these indexes were different in differentgrowing stages. The order of drought-resistance as follows: turf forming stage> emergingstage> vigorously growingstage> growingdecline stage. 5.The effects of nitrogen and phosphorus nutrition in water stress were different indifferent indexes and in different growing stages, also in different levels of fertilizers. In aword, appling P raised drought-resistance of Dichondra repens to a certain extent. P tookeffects in raising RV and SOD activity, so drought-avoidance was strengthened, and high Pwas the best. Low and middle N increased contents of Pro, SS, and Chl, so drought-tolerance... |
PDF Full Text Request