Yoshida - 1981 - Fundamentals of Rice Crop Science

NUTRITIONAL DISORDERS 185
Table 4.5. Recommended procedures for chemical analysis of
rice tissues. a
Element or Digestion or
constituent
extraction
Method of
analysis
N
Kjeldahl method Volumetric
P
Ternary mixture Colorimetric
Al
digestion
}
Fe
Si
Ternary mixture Gravimetric
K
digestion or dry
ashing
HCL extraction or Flame photometric
Na
water extraction
Ca
}
Mg
HCL extraction
Atomic absorption
Mn
spectrophotometer
Zn
Cu
B
HCI extraction
Colorimetric
CI Water extraction Volumetric
Chlorophyll Acetone extraction
Sugar
}
Alcohol extraction Colorimetric
Starch Perchloric acid
extraction
a Yoshida et al (1976).
e. Critical concentrations for deficiency and toxicity. The critical contents of
various elements for deficiency and toxicity in the rice plant are summarized in
Table 4.7. The critical content is subject to modification according to the criteria
that define the disorders, the status of other elements or substances in the soil or
plant, the growth stages of the plant, the varieties, and the climatic conditions. The
critical content obtained from a greenhouse study is sometimes too high and not
applicable to field crops. For these reasons, Table 4.7 should be used only as a
guide for diagnosis.
Table 4.6. Analysis of standard plant sample by 7 persons. a
Analyst K (%) Mg (%) Mn (ppm) Cu (ppm) Zn (ppm)
A
B
C
D
E
F
G
2.52 ± 0.03 – 17.1 ± 0.2 6.7 ± 0.7 28.4 ± 1.1
2.55 ± 0.01 – 18.2 ± 0.5 7.3 ± 1.1 29.0 ± 0.7
2.46 ± 0.01 0.178 ± 0.000 17.5 ± 0.0 5.6 ± 0.1 29.4 ± 0.5
2.42 ± 0.01 0.121 ± 0.009 20.0 ± 0.0 5.0 ± 0.1 35.0 ± 0.4
3.16 ± 0.08 0.176 ± 0.003 15.6 ± 1.3 9.1 ± 2.3 39.7 ± 6.3
2.76 ± 0.03 0.162 ± 0.025 14.1 ± 0.9 3.7 ± 0.1 31.3 ± 1.0
2.44 ± 0.01 – 17.6 ± 0.1 – 28.9 ± 0.2
a Yoshida et al (1976).