Primary Study On Drought Resistance Of Tropic Forage

In this research different concentration PEG—6000 was used to stress six Stylo varieties and seven Gramineous tropic forage varieties during germination period, and water-stressed when potted in greenhouse during infancy period. The germination percentage, germination vigor, seed germination drought resistance index , radicle length, plumule length, radicle- plumule ration was studied in the germination stage; The wilting percentage, death percentage , dull leaf percentage after water stress, plant height, leaf length, leaf breadth, leaf angle, tissue water content, WSD(water saturation deficit) ,RWC(Relative water content) ,Variation of plasmic membrane permeability, WRC (water retain capability) ,biology-yield up-ground , biology-yield under-ground was studied in the seeding stage was studied and analyzed by the means of membership function. The results showed that:(1) The radicle length and plumule length of Stylo was restricted in the water-stress, and risen with the concentration become high . and radicle- plumule ration fallen in 10% and 15% low water-stress while risen in 20% and 25% high water-stress, sharply fallen in 30% high water-stress..(2) low water-stress hasten the germination percentage, germination vigor, seed germination drought resistance index of Stylosanthes guianensis cv. Reyan No.2,S. guianensis cv. Reyan No.5,S. guianensis cv. Reyan No. 10, but above 20%, they all remarkable fallen.(3) Stylo seed germination were hurt in 25%PEG water-stress, and 25%PEG water stress is their extreme adjust capability, they were serious hurt in 30%PEG water-stress, 35%PEG water-stress is their germination critical number.(4) The leaf-reaction of Stylo and Gramineous tropic forage to water stress is different : leaf-length and leaf-width of Stylo have little change but these of Gramineous tropic forage all remarkable become narrow.(5) The rank of this stylo species from strong to weak is : S.scabra cv.Seca Vog >S. guianensis cv. Reyan No.5> S. guianensis cv. Reyan No.7> S.hamata cv.Verano> S.