Thirty-row arrayed rice mat seedlings

誌名誌名農業食料工学会誌 = Journal of the Japanese Society of AgriculturalMachinery and Food Engineers

ISSNISSN 2188224X

著者著者Andoniaina, R.M.Yakiyama, H.Shoji, K.

巻/号巻/号 80巻5号

掲載ページ掲載ページ p. 320-321

発行年月発行年月 2018年9月

農林水産省 農林水産技術会議事務局筑波産学連携支援センターTsukuba Business-Academia Cooperation Support Center, Agriculture, Forestry and Fisheries Research CouncilSecretariat

Journal of JSAMFE 80(5): 320-321, 2018

Short Report

Thirty-row Arrayed Rice Mat Seedlings

--Saving Seeds and Prolonging Plant Lifespan --

Rakoto Malala ANDONIAINA *1, Hirotsugu YAKIYAMA *2, Koichi SHOJI*1t

[Keywords] : rice mat seedlings, in-line sowing, seeds per tray, missing hills, grain yield

I Introduction

To meet the increasing worldwide demand for rice, cost reduction and higher productivity are among the essential targets for researchers and engineers. To attain this goal, high-density seedling technology has

been developed that considerably lowers the number of nursery trays to one-third, nursery costs by half and

transplanting hours to one-third. Nonetheless, because of high-density sowing, seedling growth starts to stall over 20 days after sowing (Y anmar, 2018); therefore, seedlings

need to be transplanted within a short period of time, which limits farm management, especially for large-scale

farmers. The present study proposes a new seedling arrange­

ment that reduces the quantity of seeds per tray and consequently prolongs the viability of seedlings. When

arrayed rice mat seedlings are made by sowing seeds in

lines equal to the lateral feed number of the transplanter, the mat covers the same area as that of a conventional uniformly-sown mat, but with a reduced quantity of seeds. Of particular note is that, apart from saving seeds,

the reduced density of seeds contributes to providing more nutrients, light and aeration to each plant, thus the seedlings would continue growing and last longer,

allowing a longer period of transplanting for farmers.

II Materials and methods

Two types of mat seedlings were prepared, arrayed i.

e. the experiment and uniformly-sown i.e. the control. Mature rice seeds (cultivar: Hinohik:ari) were selected in the solution of salt (specific gravity: 1.13) and soaked in

pure water at about 22'C until they bore 1.5 mm sprouts (ca. 5 days). First, 6mm wide and 7mm deep V-shape

furrows were with a grinder made on a 13 mm thick

coco-peat mat (Hakobe no ie, 2018). The grihaer that

comprised of 30 discs, equal to the lateral feed number of the transplanter, were mounted on a shaft driven by a

0.75kW-electric motor. The mat was then manually slid along guides onto the grinder table to furrow it (Fig. 1 (a)). The coco-peat mat was then placed in a tray filled with 15 mm-deep soil, 82 g of germinated seeds per tray

were manually sown into the furrows (Fig. 1 (b)), and the mat was covered with a thin layer of soil before being

watered. Mat seedlings uniformly sown with a seeding machine (THK-2009B, Suzutec Co.,Ltd Utsunomiya) were prepared by conventional methods (138 g of germinated

seeds per tray) and used as the control. The experiments were carried out in 2017. The

arrayed and the uniformly sown seedlings were 2.5 to 3.5 and 4. 0 to 4.5 leaf age, respectively, on the day of transplanting. They were transplanted on June 26th (31

and 33 days after sowing, respectively) in sections of a 900 m2 paddy field located in Chik:uzen-cho, Fukuoka, Japan, where the control seedlings were planted in eight

rows along the border of the field with 15.7 mats per 1000 m2 and the experiment seedlings (Fig. 1 (c)) were

planted in the remaining area in the center with 7.3 mats per 1000m2. An eight-row rice transplanter (YR8D, Y anmar Co., Ltd., Osaka) was used set at 30 lateral feeds

with 7 mm vertical feeds for the arrayed seedlings, and 26 lateral feeds with 13 mm vertical feeds for the uniformly sown seedlings (the farmer's default setting).

The planting pitch and depth were set to 17.3cm and 2 to 3 cm, respectively, for the both seedling types. The number of plants per hill of the arrayed seedlings was

counted two days after transplanting for a total of 160

observations. On October 16th (112 days after transplanting), 20 hill­

plants were randomly sampled in each section, and yield

*1 JSAM Member, Graduate School of Agricultural Science, Kobe University, 1-1 Rokk:odai-cho, Nada-ku, Kobe, 657-8501, Japan *2 Kita-Midorigaoka, Toyonaka, Osaka, Japan t Corresponding author : shojik@kobe-uac.jp

ANDONIAINA, Y AKIYAMA, SHOJI : Thirty-row Arrayed Rice Mat Seedlings 321 ( 71 )

Fig. 1 Preparation of the seedlings: (a) Furrowing the coco-peat mat, (b) In-line sowing at 82 g of germi­nated seeds per tray, (c) Arrayed mat seedlings on transplanting day.

components were measured. On the following day, an

area 1.5 m wide and 15 m long was harvested in each

section with a five-row combine harvester (AR585,

Kubota Co., Ltd., Osaka) and the missing hills were

investigated.

III Results and discussion

Of the arrayed seedlings, the set density of seeds has

allowed 40 % of saving per seedling tray from that of the

control. The rate of missing hills at transplanting was a

low 4.4 %, nearly the same as the standard allowance (5

%) of the transplanter test code in Japan (Mori, 1975). The

combination of the shorter vertical feed and the 30

lateral feeds setting of the machine reduced the number

of mats used per unit of area to 46 % of that with the

control. The reduced quantity of seeds per tray resulted

in 66.7 % single and 25.8 % double plants per hill, whereas

the triple and quadruple plants demonstrated only 2.5 %

and 0.6 %, respectively. In addition, the remaining seed­

lings have survived until their heading.

Table 1 Harvest details

Criteria Missing hills* (%)

Thickness of brown rice** (mm) Panicles per hill

Grain per panicle

Maturity (%)

1000-grain weight of brown rice*** (g)

Brown rice yield (g/ m2)

Combine-harvested brown rice yield*** (g/ m2)

* Missing hills upon harvesting

In-line Control 23.4 4.1 1.99 2.01 20.3 18 .8

94.3 86.9

86.9 86.7

20.9 22.1

489. 9 553.1

454.6 516.2

** Weighted average after O .1 mm-interval sieve analysis ••• Weight adjusted to 15 % moisture content

Table 1 shows the data collected upon harvesting. The

yield of brown rice of the arrayed-mat seedlings was 11

% lower than that of the control due to the large number

of missing hills (23.4 %) at harvest. This was partially

compensated, however, by the 11 % higher grain weight

per hill than that of the control. The high percentage of

missing hills of the arrayed mat seedlings resulted

presumably from the planting mechanism of the 30-feed

rice transplanter, the narrow and sharp tines of which

damaged the single seedlings although they were spared

as shown by the analysis of the plant number per hill at

transplanting. Therefore, a regular 26-feed transplanter

is suggested for use in further investigation as it has

wider and less sharp tines, although one more mat per

1000 m2 may be needed therewith.

References

Hakobe no ie, 2018. G-THE-C Ikubyo Matto [In Japanese]. https: //hakobe.org/ goods/ mat.htm. Accessed May 6, 2018.

Mori, Y., 1975. Performance of rice-transplanters as evaluated by National Test. Japan Agricultural Research Quarterly, 9 (3), 152-155.

Yanmar, 2018. Yanmar's Mitsunae. https ://www.yanmar.com/ en_th/ agri/ jp_activities/ mitsunae. html. Accessed May 6, 2018.

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(Received : 6 May 2018 · Accepted : 27 July 2018 · Question time limit : 30 November 2018)

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