Studies On Anatomical Structure Of Several Citrus Somatic Hybrids And B-deficiency Newhall Navel Orange

The citrus somatic hybrid can be used for rootstock resources and breeding,The structure of the petiole play an important role in transporting nutrition.Newhall Navel Orange is the main cultivation in south jiangxi,whose the B-deficiency phenomenon is becoming more and more serious in recent years.The symptoms of B-deficiency leaf are as following:being yellowed,thickened and crisped; the vein is bursted and becomes suberization;the growth potential of the potted root becomes weaker,and the growth increasement is decreasing.By means of paraffin method,the structure of the citrus somatic hybrid with their parents and leaf and the potted root of Newhall Navel Orange which B-deficiency were comparatively studied,With analysis of their structure,it was found that:1.The transverse structure of the petiole in the several citrus somatic hybrid and their parents(1)The structure of petiole.The structure of the somatic hybrid is the same as their parents,the petiole is composed of epidermis,cortex,vascular bundle,pith,and pith ray. In the vascular bundle,the phloem sieve tubes differentiate in the outer portion of the cambial strands,the xylem tracheary elements differentiate at the inner margins.The xylem and the phloem is assumed the concentric circle arrangement.(2)Total trachea area.The hybrids are quite different form their parents,The biggest area is the Bonaza navel,the grapefruit,diploid and the tetraploid;Next is PR tetraploid; The total trachea area of the S.tangerina(Tanaka) Tseng,the C.jambhiri and their somatic hybrid are less than the area of the PR tetraploid.What is the smallest is the area of the S.tangerina(Tanaka) Tseng + Poncirus trifoliata and Poncirus trifoliata.(3)Average trachea density.The largest of average trachea density is the S.tangerina (Tanaka) Tseng + Poncirus trifoliate,while the smallest of it is the S.tangerina(Tanaka) Tseng + C.jambhiri tetraploid.The somatic hybrid and their parents are no remarkable differences expect for the S.tangerina(Tanaka) Tseng,Poncirus trifoliate and the S. tangerina(Tanaka) Tseng + Poncirus trifoliata.(4) Trachea total/Xylem area.The biggest is the C.paradisi(Maef.) Tseng,while the least is the Poncirus trifoliata.The significant different was found between various parents and the somatic hybrid. (5) Xylem area/transect area.As the strong growth potential of the Bonaza navel and the C.paradisi(Maef.) Tseng,they and their somatic hybrid have the biggest radio,what of the Poncirus trifoliate and the S.tangerina(Tanaka) Tseng + Poncirus trifoliate is little bigger than the least radio of S.tangerina(Tanaka) Tseng + C.jambhiri tetraploid.(6)The trachea diameter.It has the same trend as the total trachea area.2.The transverse structure of leaf of B-deficiency Newhall Navel Orange(1)With the degree increasing of B-deficiency,the vascular bundle area is becoming larger,so that the epicuticle is teared,and the vein burst.(2)Xylem area/vascular bundle area.It has certain different among various degrees, but not various.(3)Phloem area/vascular bundle area.The rate is different between the different degree of B-deficiency,and the trend increases with the increasing degree of the B-deficiency.(4)Pholem fiber area/vascular bundle area.The rate declines gradually,the rate of the vein burst is just 30%of the control.(5)The changes of the leaf of the vein bursted is following:the leaf thickness is thickener than the the others degrees B-deficiency;In mesophyll cells,the change of spongy tissue is bigger than the palisade tissue.The cell of the spongy tissue increases, the arrangement is close,the intercellular space is smaller.3.The transverse structure of the potted root of Newhall Navel Orange which is B-deficiencyThe vascular bundle does not change compared with the control potted root,but there are lots of sediments in the cortex which have different sizes and even distributions.