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Study On The Physiological Responds And Root Architecturure Compatibility Of Reaumuria Soongorica Under Water Stress

Posted on:2015-05-20Degree:MasterType:Thesis
Country:ChinaCandidate:D M GengFull Text:PDF
GTID:2180330452960759Subject:Tree genetics and breeding
Abstract/Summary:PDF Full Text Request
We investigated the effect of different soil water stress on photo-protectivemechanisms, enzyme protection mechanisms, osmotic regulation mechanism, fineroot architecture and functional characteristic in2-year-old Reaumuria soongoricaseedling, Applying measure.of controlling soil water content. the reaction andadaptive mechanism of it for soil water stress were revealed.The drought-tolerantmechanisms of R. Soongorica. it can not only provide a theoretical basis forconservation, restoration and construction of R. Soongorica, but also add a newtheoretical basis for desert plants resistance. The results were as followings:1The change of chlorophyll fluorescence variables, chlorophyll content andantioxidant enzyme activity in R. soongorica seedling:1)The chlorophyll contentssignificantly decreased with the increasing of soil water stress. Compared with thecontrol, the chlorophyll contents under medium water stress and severe water stresswere decreased by15.324%,25.729%, respectively. which indicated that under soilwater stress conditions, the biosynthesis of chlorophyll were greatly influenced andthe decomposition of synthesized chlorophyll were evidently promoted, then thechlorophyll content were reduced. On the contrary with the increasing of water stressChl(a/b) increased, which showed that under soil water stress conditions, the LHCIIcontents were decreased, the capture of leaf to light energy was reduced, and then therisk of photosynthetic apparatus damaged was reduced. This is a self-regulatorymechanism of R. Soongorica adapting to stress.2) Fo increased with the increasing ofsoil water stress, on the contrary with the increasing of soil water stress Fm, Fv/Foand Fv/Fo decreased. Under the different light intensity, Y(II) and ETR decreasedwith the increasing of soil water stress in total. This meant soil water stress couldcause a certain degree of damage or reversible inactivation to its PSâ…ˇ reaction center,which could inhibit the primary reaction of photosynthesis and decrease theproduction of the Y(II) and the ETR.3) SOD activity first decreased and then showedthe increasing tendency with the increasing of soil water stress, which with theincreasing of soil water stress POD and CAT activity and MDA content increased.This indicated that under soil water stress conditions, R. Soongorica leaf couldenhance its ability to adjust to arid environment by the change of antioxidant enzymeactivity.2Characteristics of R. Soongorica seedling growth and accumulation of three mainosmoregulation content:1) Stem and leaf biomass significantly decreased with the increasing of soil water stress, and plant height gradually decreased. On the contrarywith the increasing of soil water stress ratio of root-cap, root length and root surfacearea gradually increased, and root biomass first decreased and then showed theincreasing tendency.2) Proline content in the stem and leaf, root tissue significantlyincreased with the increasing of soil water stress, which the change of soluble sugarand soluble protein content were not obvious.3) under soil water stress, the change ofsoluble sugar and soluble protein content were not obvious in different organs, whichproline content in the stem and leaf, root tissue significantly interact with increasingduring the different stage of stress. Therefore, R. soongorica seedling can effectivelydefend drought adversity and maintain plant normal growth through adjusting growth,biomass allocation and increase root-cap ratio under soil water stress, and through theaccumulation of proline content to improve plant water absorption and water-retainingcapacity.3The change of fine root architecture and functional characteristic of R. soongorica:1) The diameter and volume decreased with the increasing of soil water stress, on thecontrary with the increasing of soil water stress root length, specific root length(SRL),surface area and specific root surface area(SRA) increased, which indicated that undersoil water stress conditions, fine root of R. soongorica seedling could adapt stress bythe increasing root length, SRL, surface area and SRA and reducing the diameter andvolume. The diameter increased with the rise of root order, root length and SRLincreased, while SRA firstly increased and then reduced.2) Total C content decreasedwith the increasing of soil water stress, while with soil water stress increasing total Ncontent first decreased significantly and then showed the increasing tendency, whichdeclared that respiration of fine roots of R.soongorica seedling was restrained undermedium soil water condition. Total C content increased with the rise of root order,total N content decreased, which declared that the low roots have stronger respirationand metabolic activity.3) The root length had a highly significant positive correlationwith C content (R2=0.63**). The diameter had a significant positive correlation withC content (R2=0.48*). The SRL was negatively correlated with C content (R2=-0.49*).
Keywords/Search Tags:Reaumuria soongorica, soil water stress, antioxidant enzyme activity, chlorophyll fluorescence, osmoregulation, fine root architecture, fine root function
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