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EFFECTS OF FERTILIZER APPLICATION ON THE LEVELS OF NUTRIENTS OF
XYLEM SAP OF TEA PLANTS
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Akio MORITA and
Mitsuiku IWAHASHI
Shizuoka Tea Experiment Station
Kurasawa, Kikugawa-cho, Ogasa-gun,Shizuoka 439,Japan |
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ABSTRACT |
The growth and nutrient concentration
of xylem sap were examined of 15-year old tea plants grown on
standard-fertilized (SF) and fertilizer-free (FF) fields. The doses
of NPK were 540,180.27kg/ha/year. Xylem sap was sampled the cut-end
of stems (5 mm, 10 cm under the plucking surface) by means of vaccum
blood sampling cylinders, for 4hours on rainy days form March to
July 1990.
The Growth and nitrogen concentration of both the first and second
crop of SF were higher than those of FF.
The amounts of xylem sap collected during the period almost exceeded
2 ml which sufficed for the analyses. The pH values of xylem sap
ranged 5.2-6.3 which declined at the first and second flush. While
EC values peaked during the same periods. The levels of total amino
acids, phosphoric acid and potassium of tea sap also peaked at the
first and second flush but remained low in other stages. Their
concentrations of the first flush were much higher compared with
those of the second.
Higher levels of total amino acids
were observed in xylem sap of SF than in that of FF suggesting that
the dressing of nitrogen increase.
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INTRODUCTION |
It is well known that the amount of
translocation of nutrients from roots to above-ground parts affects
much on the yield and quality of the plant. Therefore, works have
been done on nutrients of the sap of xylems of many plants 1,2,4).
In the case of tea plants, similar studies have been pursued and
reports have been made on the movement of nitrogen elements within
the plants 3.6). However, there is a few case of sampling sap in tea
fields 5) and there is no information on the seasonal fluctuation of
nutrients of the sap of tea plants. This has been because the
tapping of sap required special apparatus and electricity for vacuum
pump and therefore could not be performed at any suitable locations
and it took time to install the apparatus. The authors, for this
reason, contrived a few anywhere. By trying its practical use, it is
confirmed that this device can tap enough amounts of tea sap for
analyses.
Thus, by using the kit, the sap of tea plants was sampled from the
tea fields with different ferilizer treatments from March to July.
and the seasonal fluctuation of the levels of nutrients in the sap
as well as the effect of fertilizing were examined.
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MATERIALS and METHODS
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Standard-ferilizer (SF) and
fertilizer-free (FF) plots were established in the tea field
(16-year old. c.v. YABUKITA) of Shizuoka Tea Experiment Station
since 1986. No fertilizer was applied in the FF plots and NPK
(540-180-270kg/ha/year) was applied in the SF plots. Other
management practice was indentical for the both treatments.
The first and second crop of both
treatments was plucked on 1st. MAY and 23rd. June 1990 respectivly.
6 squarerot (20 x 20 cm) samplings were made from each treatment and
fresh weight of the samples was regarded as the amount of growth.
The samples were then dried and pulverized for analyses.
The sampling of xylem sap was done in the method shown in Fig.1. The
kit consisted of a vaccum blood sampling cylinder (20 ml, 135 mmhg,
NIPRO & CO. LTD), a holder of the cylinder, a needle, an inlet
packing of gas chormatograpghy equipment and a Teflon tube. 5 kits
were set on the shoots with diameter of 5 cm (10 cm blow the
plucking surface) at one time and sap was collected for 4 hours from
9 AM to 1 PM. The amounts of sap. pH and electric eonductivity (EC)
were measured immediately after the collection. and the sap samples
were frozen and stored for analyses. sap was analyzed for amino acid
by colorimetric method 7), phosphoric acid by liquid chromatograthy
and potassium by atomic absorption spectrophotometer.
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RESULTS AND
DISCUSSION
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As shown in Table 1. the SF treatment
gave higher amounts of growth and total nitrogen than the FF
treatment and the effect of fertilizing was evident.
It was impossible to sap with this
kit during the fine daytime, while it was possible during the
nighttime and rain. It was considered that this was because
evaoratin activity of free foliage was much more vigorus than
sucking ability of the cylinder and sap was consumed by foliage
during the fine daytime. Therefore, sampling of sap was made during
rain when its success was assured. FIg.2 shows sufficient amounts of
sap were collected for analyses throughout the period. There was no
difference on the amounts of sap between the treatments but they
appeared affected much by weather condition at sampling.
The pH values of sap ranged in the
weak acid area of 5.2 to 6.3 and tended to come to the lowest around
the first and the second harvest. And more lowering of the values
was oberved in the in the SF treatment, suggesting that the levels
of nutrients related to the dressing were higher as new shoots grew.
The EC values of sap began to
increase at bud opening and peaked at the harvests and declined
thereafter. The EC values of the SF treatment were higher than those
of the FF treatment and influence of the fertilizing was observed.
Both amino acids and phoshoric acids
in sap gradually increased from the time of bud opening and peaked
around the harvesting period (Fig.3.4). Potassium co
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