§硬質小麦の高品質安定生産を実現する省力施肥技術の開発
Agricultural Research Division, Mie Prefectural Agricultural Research Institute
研究員　内山　裕介
(現 四日市農林事務所　四日市鈴鹿地域農業改良普及センター　鈴鹿普及課　主任)
§Seedling boxes and pooled seedlings go hand in hand.
Jcam Agri Corporation Tohoku Branch
技術顧問　上野　正夫

　

　

High quality stable production of hard wheat
実現する省力施肥技術の開発

Agricultural Research Division, Mie Prefectural Agricultural Research Institute
研究員　内山　裕介
(現 四日市農林事務所　四日市鈴鹿地域農業改良普及センター　鈴鹿普及課　主任)

Introduction

　Mie Prefecture has a wheat crop area of 6,590 ha (2018 crop statistics from the Ministry of Agriculture, Forestry and Fisheries), and four varieties of hard and soft wheat are grown in the prefecture. Demand for prefectural wheat continues to outstrip supply due to strong demand from actual consumers, as evidenced by its use as an ingredient in the local delicacy "Ise Udon," and increased production of both hard and soft wheat varieties is required.

　しかし，昔から「麦は肥料で獲る」と言われるように，麦栽培には施肥管理が肝心で，特に硬質小麦を高品質安定生産するには基肥施用に加え，３回の窒素追肥が必要となるため大きな労力を要する。また，生産現場では経営規模拡大により春先の水稲作との作業競合が生じ，生育後期の適期追肥を行えずに品質・収量が低下する場面が見受けられる。これらの対策として肥効調節型肥料による省力的施肥技術が望まれているが，今まで硬質小麦に特化した肥効調節型肥料はなかった。
　そこで，省力的に硬質小麦を高品質安定生産することを目的に，硬質小麦用肥効調節型肥料の開発を検討したので紹介する。

Details of the study

(1) Study of labor-saving fertilizer application system

　研究所内（松阪市）および現地圃場（玉城町)において，表１に示した省力施肥体系と慣行分施体系（追肥３回）を３年にわたり（2014年，2015年，2016年播種）比較検討した。

　省力施肥体系は，速効性肥料：リニア２０日タイプ肥効調節型肥料（以下，L20型)：シグモイド30日タイプ肥効調節型肥料（以下，S30型）をそれぞれ20：40：40%の割合で配合した「小麦専科32」を試験資材とし，その参考として，県内で普及している既存の肥効調節型肥料である速効性肥料：リニア30日タイプ肥効調節型肥料（以下，L30型)：S30型をそれぞれ35：40：25%の割合で配合した「麦エムコート28」(ともにジェイカムアグリ株式会社）を基肥時に窒素量1.6kg/aで全量施用した。

　Hard wheat "Nishino Kaori," which accounts for about 20% of the wheat cultivated area in the prefecture, was used for the study and sown in mid-November (November 7, 2014, December 2, 2015 (re-sown due to rainfall after sowing), and November 18, 2016), which is considered the best time to sow the seeds.

(2) Nitrogen elution pattern of L20 and S30 types

　省力施肥体系で用いたL20型とS30型について，土中への埋め込みによる溶出試験を実施した（図１) 。
　The results showed that fertilizer nitrogen elution of the L20 type was about 701 TP3T from sowing to the ear formation stage. On the other hand, the S30 type started leaching around the time of ear formation, and leached about 201 TP3T by the time of the beginning of leaf extraction, and about 601 TP3T by the time of flowering, and continued leaching thereafter.

(3) Labor-saving fertilizer application system maintained the same level of growth as the conventional system throughout the growing season.

　The relationship between fertilizer application and growth is shown in Table 2. From the time of sowing to the beginning of leaf extraction, the labor-saving fertilizer systems ("Wheat Specialty 32" and "Wheat M-Coat 28") showed the same level of growth as the partial fertilizer systems. This also confirmed that nitrogen leaching from the fertilizer regulated fertilizer was sustained, similar to the results of the above-mentioned embedded test.

4) "Wheat Senka 32" improves the quality of hard wheat compared to "Mugi M Coat 28

　The relationships among yield, yield components, and protein content are shown in Table 3. In terms of protein content, one criterion for evaluating the quality of hard wheat, "Wheat Senka 32" had higher protein content than "Wheat M Coat 28," which is the same labor-saving fertilizer system, and improved the quality of hard wheat.

　This is thought to be due to the fact that "Wheat Senka 32" contains more S30 type nitrogen that is continuously leached out after the flowering period than "Wheat M Coat 28".

(5) Labor-saving fertilization system has the same yield and slightly lower protein content than the conventional partial fertilization system.

　The labor-saving fertilizer system resulted in similar yields (top wheat weight) compared to the conventional fertilizer system. In addition, the labor-saving fertilizer system met the standard value for hard wheat protein content (11.5-14.01 TP3T), except for "Wheat Emcote 28" sown in 2015, which had a slightly lower protein content than the conventional partial fertilizer system when the leaf color at ear emergence was low, as in the 2015 and 2016 sowings (Table 3 Table 3).
　This was thought to be because labor-saving fertilization systems are affected by temperature and rainfall (Figure 2), and nitrogen leaching from flowering to maturity may be insufficient.

(6) Effects of labor-saving fertilizer application on the field

　In recent years, the spread of labor-saving fertilizer application technology has reduced the number of farmers who say that they have missed the right time for fertilizer application. Labor-saving fertilization technology is becoming a "good-luck charm" for farmers that guarantees stable wheat production, and the time and mental leeway afforded by this "good-luck charm" are leading an increasing number of farmers to take initiatives aimed at achieving higher quality and yield.

　Thanks to these efforts, the prefecture's wheat crop sown in 2018 achieved the highest unit yield in recent years, and farmers in the field are becoming even more enthusiastic about wheat production. For example, an increasing number of farmers are taking on "things they have wanted to do but have not been able to," such as drainage measures, application of soil fertility materials, and multiple control of red mold.

　Thus, labor-saving fertilizer application plays a role not only in wheat production but also in motivating farmers in the field, and is expected to continue to develop in the future.

　

　

Pooled seedling cultivation is a perfect match for boxed seedlings.

Jcam Agri Corporation Tohoku Branch
　技術顧問　上野　正夫

Introduction.

　Pool seedling cultivation is a method of seedling cultivation in which the seedling beds are surrounded by wooden frames and covered with plastic to enable waterlogged conditions. This method originated in Miyagi Prefecture, and has come into the limelight as a labor-saving water management method that allows seedlings to be flooded during the latter half of seedling growth, without the need to worry about frequent irrigation, especially after the Golden Week holiday season. The author has had a lot of experience with seedling management using the seedling box-assigned seedling management method, and believes that pooled seedling management is the best method for seedling management using the seedling box-assigned seedling management method. In particular, seedling box-assigned seedling growth may lead to insufficient moisture in the seedlings due to less bed soil than usual. We believe that the key to healthy seedling growth is to maintain the seedlings in a "water-supplied seedling bed" as soon as they are ready to sprout, which is why we promote pool-grown seedlings.

　In this section, we will discuss the specific methods. In addition, I would like to point out the importance of spraying Tachigalene Ace M solution as an essential "measure for preventing mulled seedlings" during the Golden Week period.

1. what to do before sowing (salt water selection, disinfection, soaking, sprouting, shade drying)

　Salt water sorting is used to select well-developed seeds and to ensure uniform germination. The salt water sorting can remove the fungal seeds and can be used in combination with seed disinfection to increase the effectiveness of seed control. The specific gravity of the brine selection is 1.13 for Uruchi and 1.08 for Mochi. Soaking is performed to supply moisture necessary for germination, and is carried out until the accumulated water temperature reaches 100℃ and the paddy weight increases by 20 to 25%. When the water temperature is 15°C, about 7 days of soaking is required.

　Insufficient soaking time will result in uneven germination, so it is important to allow sufficient time for water supply. In particular, soaking should be done in a net bag with plenty of space and shaken every 2 to 3 days to prevent uneven absorption of water. The water temperature should be kept below 15℃ and the water should be changed every 2 to 3 days. After that, the fully soaked paddy should be placed in a "pigeon chest" condition in a rice germinator. The soaking process is important in relation to the seeding process, and care should be taken not to allow the roots to emerge. The seedlings should be dried in the shade one or two days before sowing to prepare them for the sowing operation.

2. be careful with seedling bedding soil

　The pH should be 5 to 5.5, and about 2g of each of N, P, and K per box as a fast-acting fertilizer is required. In the case of seedling box-assigned seedling growth, fast-acting fertilizer is also necessary, and 1 g of N, P, and K per box is the appropriate amount, so there is no problem in using conventional seedling bedding soil (because less bedding soil is needed for seedling box-assigned seedling growth). For seedling cover, use granular, fertilizer-free soil. In particular, use granular soil because powdered soil can become muddy and impair germination.

3. seedling growth is based on seed root elongation

　The first requirement for a healthy seedling is "mat formation. If the seedlings cannot be planted by a rice transplanter, they cannot be considered healthy. The seedlings should be well rooted, of adequate length (12 to 16 cm), and the N concentration of the seedlings should be about 3.5 to 4.51 TP3T to complete a rolled mat. In addition, it is often observed that lightweight media do not slide well on the seedling feeder of rice transplanters. Please keep in mind that it is necessary to absorb water beforehand.

　Naturally, it is important to manage seedlings sufficiently to prevent them from growing too tall. Seedlings tend to grow more easily in the first half of growth than in the second half. Budding length increases easily, and the height of the first and second leaf sheaths also increases quickly, resulting in "short seedlings. In order to produce "Zunguri" seedlings, which are synonymous with healthy seedlings, we need to pay attention to excessive growth in the early stage of growth above all. In particular, bud length should be within 1 cm and leaf sheath height should be as short as possible. Please understand that the risk of overgrowth is much greater than the risk of no budding. In the past, you may have experienced problems with seedlings not growing long enough, but in the age of greenhouse seedling production, there have been few problems with seedlings not growing long enough.

　極端なことを言えば，芽が5mm程度に揃ったら即座に被覆資材を除去し，プール育苗の方は「水苗代状態」に管理してください。水稲は水の稲と書きます。出芽後水苗代状態にして全く問題がありません。これまで，出芽〜緑化期にかけては灌水を少なくして地温上昇に心がけてくださいと言ってきました。地温を上げることで根の伸長を助けることはその通りです。

　しかし，ハウス育苗で地温が上がらない等の問題は起こり得ません。それよりも出芽揃い時以降の水分不足のリスクの方がはるかに大きいと考えます。苗箱まかせの育苗は土が少ない分水分不足が問題になるのです。プール育苗では，苗代初期にプール状態を維持できるのです。苗箱まかせとプール育苗の相性の良さはここにあるのです。

　We have discussed the importance of rooting. The first thing that is necessary for good rooting is early budding growth. Needless to say, the initial growth of all plants is important. In rice seedling production, the goal is to achieve uniform growth without increasing bud length. Figure 1 shows the importance of self-sprouting roots (seed roots) as the key to seedling development. Rice seedlings depend on endosperm nutrients until the first leaf stage. Therefore, rice seedlings grow normally until the first leaf stage unless there is a serious problem.

　However, when the endosperm nutrients run out, the seedlings begin to absorb nutrients and water through their own roots. If these roots do not grow, rice seedling growth will be fatal. Seedlings that are under-irrigated at sowing (water does not reach the bottom of the seedlings and stays only on the surface) will not be able to grow roots and will be unable to pull off the seedlings. This is why it is important to irrigate the seedlings thoroughly at the time of sowing. For seedlings grown in a seedling box, it is most important to manage the seedlings so that there is not a shortage of water when the roots begin to grow. The reason why the author recommends "box-bottom fertilization" is also to consider the surrounding conditions of the seed rice when nadir roots begin to grow. In the "layered fertilization" method, the seed and the box are coexisting. In box-bottom fertilization, the seed is surrounded by soil because the seedling box is at the bottom of the box. This results in a difference in moisture retention. This is the reason why we encourage box-bottom fertilization.

　We believe that box-bottom fertilization is superior, especially when irrigated from above. However, this does not mean that layered fertilizer application is to be rejected. If irrigation is done carefully and seedlings are grown in a pool, there is no problem with either layered fertilization or box-bottom fertilization. Again, it is important to keep the seedlings in a "waterlogged nursery" to prevent water shortage from the early stage of germination onward. This is why pooled seedling management is recommended.

　Figure 2 shows the situation in Yamagata Prefecture where seedlings are raised in greenhouses. In the greenhouse method, seedlings are irrigated in four different ways: by placing them in a sprouting container, by placing them directly in the greenhouse without sprouting container, and by irrigating the seedlings from the top or by irrigating them in a pool. The amount of fertilizer applied to each seedling box was 1 kg/box of N400-100 in kind. Good seedling growth was achieved in all cases.

4. the occurrence of uneven seedlings

　Mushy seedlings are the biggest problem for paddy rice seedlings. Mushy seedlings initially show physiological symptoms, but when Pisum sativum is involved, the disease spreads rapidly and causes seedling dieback. In the field, the problem is rarely observed until Golden Week.

　After Golden Week, the seedlings will have two leaves fully developed and three leaves will begin to emerge. In short, the leaf area index reaches its maximum. During this period, temperature fluctuations are likely to occur due to frequent high and low temperatures. In particular, excessive high temperatures and low temperatures can easily lead to saplings that are saprophagous. In short, at this time of the year, the seedlings are in a struggle between the disease and the seedlings. If the seedlings grow too long and soft, they will be susceptible to disease. If the root growth is strong and the seedlings grow into small, slimy seedlings, the disease will be overcome and the seedlings will grow normally.

　以前，床土は自家生産が一般的な時代はタチガレン粉剤の混入は容易に行われていました。ところが，購入培土が普及するにつれタチガレン粉剤の散布が行われなくなることが多くなってしまいました。この場合は，ゴールデンウィーク以降に現れるムレ苗の初期症状（円形状に現れる場合が多い）を見逃さないことです。その時点で即座にタチガレンエースM液剤500倍，500cc/箱を散布してください。ムレ苗に罹った苗の症状は治りませんが，周囲への蔓延を確実に防止します。
　タチガレンエースM液剤は500cc瓶で3000円強の値段です。この500cc１本で育苗箱500枚を賄うことができます。ムレ苗の初期症状を見逃さないでください。

5.Spray Tachigalene Ace M solution immediately after the initial symptoms of seedlings with swelling.

　Photographs 4-1 to 4-4 show the condition of seedlings after the seedlings were sprayed with Tachigaren Ace-M solution at 500 times, 500 cc/box, immediately after the seedlings became infested with soggy seedlings. Although Tachigalene Ace-M solution did not cure the symptoms of infested seedlings, it completely prevented the infestation of infested seedlings at the time of final rice transplanting.

6. when the initial symptoms of seedlings with murae were identified but no spray of Tachigaren Ace M solution was applied.

　The seedlings were sown on 4/21 (covered with perforated polyethylene) and were greening up in the perforated polyethylene on 4/29 due to the significant delay in removing the perforated polyethylene covering. The growth was good, although the plants were growing long. Under these conditions, we observed the initial symptoms of seedlings that were growing unevenly on 5/11. At this point, Tachigalene Ace M solution should have been applied, but was not. The problem is that we did not spray Tachigalene Ace M solution immediately after confirming the early symptoms of purple seedlings (typical circular symptoms of purple seedlings).

7. when Tachigalene Ace M solution is applied immediately after the initial symptoms of seedlings with murae.

　The farmer in charge immediately sprayed the seedlings with Tachigaren Ace M solution, 500 times 500 cc/box, which completely prevented the spread of the saplings. The first occurrence of "Mure" seedlings was confirmed on 5/18. The spraying of Tachigaren Ace-M solution 500 times 500 cc/box at the time of the first occurrence of infestation of saplings is very important.

Conclusion

　Pooled seedling management has traditionally been used for water management from the 1.5-leaf stage onward and in the mid- to late-season. However, for seedling box-based seedling management, the ability to maintain waterlogged conditions from the early to mid-emergence stage is of utmost importance. As shown in Photos 1 and 2, waterlogging is maintained as soon as seedlings have sprouted to 0.5 cm to 1 cm in length. The waterlogging condition varies depending on the condition of the pool bedding, but it does not matter. After the first leaf stage, the top of the box should remain waterlogged. This will ensure that the seedlings have good mat formation. Pooled seedling production is a perfect match for boxed seedling production.

　つぎに，ゴールデンウィーク以降に散見される「ムレ苗｣ ，それまで全く問題が生じなかった育苗で「ムレ苗」に侵されれば一朝一夕にして無残な状態に陥ります。まずは「ムレ苗」の初期状態を把握することです。初期状態である円形症状を確認したら即座にタチガレンエースM液剤500倍，500cc/箱を散布することです。症状が出た苗は治癒しませんが確実に蔓延を防止できます。ここ何年か「ムレ苗」症状に悩んでいる場合は，ゴールデンウィーク後半に予防的にタチガレンエースM液剤500倍，500cc/箱の散布を行い，健全な苗を安心して作りたいものです。