Studies on the Physical Characteristics of Rice Seedling
VI. The effects of some conditions in raising of seedling
1978 Volume 47 Issue 1 Pages 111-117
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1978 Volume 47 Issue 1 Pages 111-117
To obtain good seedling which was capable of producing high yield and was suitable for mechanical transplanting, some experiments on raising of seedling were conducted under various nursery conditions (i.e. (1) seeding rate 90-720g/m2, (2) upland or lowland nursery bed and (3) nursery period 19-48 days).
1. Physical characteristics were influenced apparently by seeding rate. Comparing with the seedling grown under dense seeding rate, the one grown under sparse seeding rate was (1) thicker in basal section (increase in section modulus), (2) more resistant to buckling and bending (increase in buckling index), but (3) more flexible in the structure (decrease in buckling stress) of basal part. Seedling grown under sparse seeding rate also possesses well-developed basal part with short foliage, therefore (4) more resistant against to buckling and bending of whole seedling (decrease in buckling index and deflection rate).
2. Comparing with the seedling grown in lowland nursery, the one grown in upland nursery was (1) thinner in basal section (increase in section modulus), (2) more rigid in the structure of basal part (increase in buckling stress) and (3) more resistant to buckling and bending, which were due to the well-developed basal part with erect and short foliage (decrease in buckling index and deflection ratio).
3. Physical characteristics of seedling in relation to nursery period were as follows: -
With growing, the basal part of seedling became (1) thicker in section (increase in section modulus), (2) more rigid in the structure (increase in buckling stress), therefore more resistant to buckling and bending (decrease in buckling moment). (3) In early seedling stage, the resistance against to buckling and bending of whole seedling (buckling index and deflection ratio) was not so high because of the undeveloped basal part. It increased once because of the developed basal part in comparison with foliage growth, but decreased again because of foliage elongation when nursery period was too long.
4. The above mentioned results on physical characteristics were similar to the well-known informations on physiological characteristics of seedlings. It was informed that the seedling grown under sparse seeding rate or the seedling grown at upland nursery was generally healthy and capable of producing high yield under the paddy field condition after transplanting. Similarly, the seedling grown under same conditions possessed better physical characteristics which were beneficial for mechanical transplanting.
