Jiban
Krishna Biswas, Ho Ando, Ken-ichi Kakuda and Benito H. Purwanto
Soil Sci.Plant
Nutr. 47-3, 477-488 (2001)
Key Words: Calcium peroxide, dissolved oxygen, genotype,
seedling establishment, soils
Unstable seedling establishment is still noticed when
calcium peroxide-coated seeds are used for uniform seedling establishment
in direct-seeded lowland rice culture. To observe the genotype response
of calcium peroxide-coated seeds, Oryza sativa L. var. Haenuki and Sasanishiki,
were grown in test tubes and in plastic pots containing soils from: Oami
hill (Oami B) and Akita prefecture (Akita calcareous) (Experiments 1 and
2). The soils collected from upland and lowland areas from the Shonai Agricultural
Experiment Station (Shonai alluvium), Yamagata University farm (University
alluvium) and Shinjo Agricultural Experiment Station (Shinjo volcanic),
Yamagata Prefecture, Japan were used to observe the response of soil types
and soil sources in Haenuki in the case of calcium peroxide-coated seeds
(Experiment 3). The seedlings were grown under hypoxic conditions at 30oC.
The growth duration for in-vitro culture was 7 d in the dark and 10 d for
pot culture in the phytotron under natural day and night conditions. The
Akita calcareous soil failed to accumulate dissolved oxygen even when calcium
peroxide-coated seeds were sown. Seedling establishment of Haenuki was
slightly affected regardless of whether coated or non-coated seeds
were used in the Oami B and Akita calcareous soils. The coating of seeds
of Sasanishiki, led to poor seedling establishment in these soils,
whereas in the case of Sasanishiki, seedling establishment was as
good as that of Haenuki when the seeds were not coated in the Oami B soil.
In Haenuki, plant height increased when coated seeds were used in in-vitro
culture but in pot culture, plant height was similar between the coated
and non-coated seeds in both soils (Experiments 1 and 2). Haenuki also
showed a similar seedling establishment between coated and non-coated seeds
in the Shonai alluvium upland and lowland, University alluvium upland and
Shinjo volcanic lowland soils. However, in the case of the calcium peroxide-coated
seeds, plant height was adversely affected in the Shonai and University
alluvium upland soils. In the University alluvium lowland soil, seedling
establishment was markedly reduced when coated seeds were used. As the
degree of reduction in this soil was not conspicuous, the worst performance
of Haenuki might be attributed to factors other than anaerobic toxins like
volatile fatty acids or hydrogen sulfide (Experiment 3). This study revealed
that the efficacy of calcium peroxide coating of seeds varied with the
genotypes, soil types and soil sources.