Pushing Resistance Research Articles

Identification of quantitative trait loci for resistance to bending-type lodging in rice (Oryza sativa L.)

Bending-type lodging is one of the most important factors affecting the yield and grain quality of rice. This study identified quantitative trait loci (QTLs) for physical strength of the upper culms, and evaluated QTL effects on lodging resistance. In 2010 and 2011, QTLs for breaking strength, length, and diameter of the top three internodes were identified by analyzing chromosomal segment substitution lines (CSSLs) developed from ‘Koshihikari’ and ‘Kasalath’. The QTL analysis indicated that ‘Kasalath’ had two types of QTLs: one to strengthen specific internodes and one to simultaneously improve the physical strengths of plural internodes or the top three internodes. A QTL for breaking strengths of the top three internodes (bsuc11) was detected on chromosome 11 in both years. This QTL did not overlap with that for internode length. To evaluate the effects of bsuc11 on lodging resistance, this study selected three CSSLs with bsuc11 and analyzed the breaking strengths of the top three internodes after heading and the pushing resistance of the lower part. Internodes of ‘Koshihikari’ showed decreased breaking strengths after grain filling, while those of CSSLs with bsuc11 did not show this decrease in breaking strength. The pushing resistance of the lower part at the fully ripe stage was the same in ‘Koshihikari’ and CSSLs with bsuc11. These results suggested that bsuc11 could be a target to improve the physical strength of the upper culms to resist bending-type lodging, and that the physical strengths of upper and lower parts are controlled by different genetic factors in rice.

Preventive Resettlement of Migrants Inspiration Mechanism in Three Gorges Barrier Region

This paper will employ the push-pull theory and Todaro Model of migrants to analyze push force, pull force and resistance and make a multi-dimensional analysis of the relationship of migrants and disaster reconstruction from the perspective of people-land, people-economic, people-social relation. On basis of this, this paper will investigate the gap between the basic appeal from immigrant people in Three Gorges Reservoir Region due to geological disaster and policy supply as well as build a scientific incentive mechanism (interest inspiration, policy guarantee, desire inspiration of livelihood) for population transfer. The practice indicates that establishment of the mechanism provides an important guarantee for smooth implementation of the immigrant project in Three Gorges Reservoir Region and raises Three Gorges people willingness to immigration.

Numerical Analysis Method of Coke Pusher Ram Based on ANSYS

This article describes a numerical analysis method based on ANSYS used to simulate the whole working process of coke pusher ram. Works have done included the following aspects: the coke pushing resistance curve has been determined; the basic ideas and methods which can treat contact problem, moving loads and other problems in the ANSYS have been introduced, provides a reference for the solution of similar problems.

Key Technology of Refined Cotton Centrifuge Unloading

On the basis of studying the principle of centrifugal dewatering technology applied to refined cotton, the paper analyzes the key technologies of screen plugging and pushing resistance concerning problems of cotton fiber blocking screen stencil and impracticality of pushing when refined cotton is tested on P-60 centrifuge, in combination with refined cotton’s properties. Besides, measures of improvement are proposed as to the design of the centrifuge’s main components’ structures, which lays a good foundation for further development of refined cotton centrifuge.

Lodging resistance locus prl5 improves physical strength of the lower plant part under different conditions of fertilization in rice ( Oryza sativa L.)

High fertilizer application rates increase grain yield and biomass in rice, but reduces lodging resistance. Lodging resistance locus prl5 enhances pushing resistance through delaying leaf senescence and increasing carbohydrate reaccumulation in stems. This study demonstrates the effects of prl5 under different levels of Nitrogen·Phosphorus·Potassium basal fertilizer application using a chromosome segment substitution line based on the genetic background of Koshihikari, which contains prl5. High fertilizer application rates enhanced pushing resistance of the lower part, but did not consistently affect the pushing resistance of the whole plant. Independent of fertilizer application rates, prl5 enhanced pushing resistances of both the lower part and the whole plants. Plant height, biomass and grain yield were increased by high fertilizer application rates, but stem diameter and the dry weight of basal culms did not show consistent increases as determined over a period of 2 years. In leaves just after heading, chlorophyll (Chl) contents, rather than Rubisco contents, were correlated with fertilizer application rates. At the fully ripe stage, fertilizer application did not affect Chl and Rubisco contents in leaves, while prl5 increased the contents in the second leaf. High fertilizer application rates did not affect the concentration of non-structural carbohydrates (NSCs) in basal culms, but prl5 increased them at the fully ripe stage. These results suggest that fertilizer application reduces lodging resistance by highly elevating the center of gravity, but that prl5 can counteract this effect by enhancing the physical strength of the lower part through delaying leaf senescence and increasing NSC reaccumulation in culms without any effects of different fertilizer application rates.

Improvement of lodging resistance with QTLs for stem diameter in rice (Oryza sativa L.)

Varietal differences among ten rice cultivars showed that stem diameter is a key factor in lodging resistance (measured in terms of pushing resistance). Two near-isogenic lines (NILs) were selected from a series of chromosome segment substitution lines developed between cultivars Nipponbar and Kasalath, one containing a single stem diameter QTL (sdm8; NIL114), and another with four stem diameter QTLs (sdm1, sdm7, sdm8, sdm12; NIL28). Compared with the Nipponbare control, stem diameters were larger in NIL114 and NIL28 by about 7 and 39%, respectively. Pushing resistance in NIL28 was significantly greater than in Nipponbare, but NIL114 was similar to Nipponbare. The two NILs had greater weight of lower stem and culm wall thickness than Nipponbare. NIL28 had higher plant height, which is a negative effect on lodging resistance, than Nipponbare. The non-structural carbohydrate contents of NIL stems were higher than that of Nipponbare, whereas the silicon contents were lower in the NILs, and cellulose contents were lower only in NIL28. The basal internodes of the two NILs were significantly stiffer than those of Nipponbare. These results suggest that increasing stem diameter in rice breeding programs would improve lodging resistance, although the combination of multiple QTLs would be necessary to produce thicker stems with higher pushing resistance, whereas the higher plant height could also result from the combination of multiple QTLs.

Improved Lodging Resistance in Rice (Oryza sativa L.) Cultivated by Submerged Direct Seeding Using a Newly Developed Hill Seeder

Submerged direct-seeded rice is more susceptible to lodging during the ripening period than is transplanted rice. Comparing different seeding methods of direct seeding cultivation, lodging resistance is considered to be highest in hill-seeded rice. However, practical hill-seeders did not exist, and previously direct-seeding had been conducted by broadcast- or row-seeding. This paper discusses the development of a hill seeder and improvements in the lodging resistance of hill-seeded rice, both of which have contributed to the recent widespread cultivation of submerged, direct-seeded rice in Japan. The newly developed hill-seeder effectively drives seeds intermittently into the puddled soil and enabled establishment of a hill which is composed of several plants as is a transplanted hill. Hill-seeded rice showed remarkable higher pushing resistance than broadcast-seeded rice across a range of seedling density and seeding depth after heading, while the plant length was longer in hill-seeded rice. It is suggested that the high lodging resistance of the hill-seeded rice is derived from the larger number of panicles per hill, because the lodging resistance varied depending on the number of panicles in a hill. The area cultivated by hill-seeding has been increasing since 1998, in 2004, it occupied 25% of the total submerged direct-seeded area.

Identification and functional analysis of a locus for improvement of lodging resistance in rice.

We identified a new locus responsible for increased pushing resistance of the lower part of rice (Oryza sativa) and analyzed its physiological function to understand how to improve lodging resistance in rice. Quantitative trait loci (QTLs) controlling pushing resistance of the lower part were analyzed in a population of backcross inbred lines of japonica Nipponbare x indica Kasalath plants cut out at 40 cm to exclude the effect of the weight of the upper parts. Five QTLs for pushing resistance were detected; only one QTL from Kasalath on chromosome 5 (prl5) had a positive effect. The likelihood odds ratio curve of prl5 echoed that for lodging resistance by typhoon. We selected three near-isogenic lines (NILs) in which the chromosomal region of prl5 was substituted with that of Kasalath in the Nipponbare background. The dry weights and densities and the contents of accumulated carbohydrate in stems below 40 cm (lower stems) in each NIL were significantly higher than those of Nipponbare. There was no difference between Nipponbare and the NILs in yield, root characteristics, or the weights of the upper parts. Pushing resistance of the lower part and lodging resistance in the NILs were up to twice as high as in Nipponbare. These results suggest that prl5 might affect the characteristics of the lower stems of the NILs, thus increasing lodging resistance.

Effect of Field Drainage on Root Lodging Tolerance in Direct-Sown Rice in Flooded Paddy Field

To elucidate the effect of drainage of paddy fields on root lodging tolerance in direct-sown rice, we measured the pushing resistance (R), diameter of hill at the base (Dm), shoot dry weight (Ws) and root dry weight (Wr), in rice varieties grown using several irrigation management schemes that differed in the frequency and length of field drainage during the growing season. Soil hardness was also monitored to investigate the relationship between the variance of soil physical properties caused by different irrigation treatments and root lodging tolerance. Pushing resistance moment (Rh), i.e., product of pushing resistance (R) and height of pushed part of hill (h), showed higher values in rice grown in fields drained more frequently or for longer periods. A similar pattern was found in rice grown in field plots where root penetration to the subsoil layers was prevented by laying an unwoven cloth between the topsoil and subsoil layers. Higher values for pushing resistance efficiency based on root dry weight (Kr : Rh/Wr/Dm) were also found in plots subjected to more frequent or prolonged drainage, irrespective of rice variety. Soil hardness was progressively increased by each field drainage during the growing season, and showed a highly significant relationship with Kr. The above results suggest that field drainage increases the root lodging tolerance in direct-sown rice through improvement of anchoring ability caused by increased soil hardness.

Improvement of Lodging Resistance in Submerged Direct Seeding Rice (Oryza sativa L.) Cultivation Using a Newly Developed 'Shooting hill-seeder'. Effect of seedling density on the lodging resistance of hill-seeded rice as compared with that of broadcast-seeded rice.

打込み式代かき同時土中点播機を用いた安定的湛水直播栽培法の確立のため, 異なる苗立ち密度(40, 80および160本m-2)における耐倒伏性を散播水稲と比較して点播水稲の耐倒伏性に関する特性解明を行った. その結果, 点播水稲は散播水稲に比較して稈が長くなるために稈基部にかかる力が大きくなるが, 有効茎歩合が高いために耐倒伏性に関連した稈の形質が優れること, 押し倒し抵抗値が顕著に大きいことにより稲株の耐倒伏性が強化され, 倒伏を生じにくいことが明らかとなった. また, このような播種様式間差は苗立ち密度の高い条件で顕著となった. 押し倒し抵抗値の変動要因を検討した結果, 散播水稲において1株穂数が10本以下の株は押し倒し抵抗値の変動が大きく, 1株穂数の減少により抵抗値が顕著に低下するのに対し, 1株穂数が10本以上の株は押し倒し抵抗が安定して高かった. このことから, 散播水稲では苗立ち密度40本m-2以上の条件では1株穂数が10本以下となるために, 苗立ち密度の変動により1株穂数が変動するのに対し, 点播水稲は標準的な播種条件(条間30cm, 株間20cm)では苗立ち密度が40～160本m-2(1株苗本数が2～10本)の間で変動しても1株穂数が20～26本と安定して多いことにより, 苗立ち密度が変動しても点播水稲の耐倒伏性が安定して高いものと推察された. 湛水直播栽培では苗立ち密度の変動が避けられないため, このような特性を有する点播栽培は湛水直播栽培の安定化に有効であると考えられる.

Selection Effectiveness of Lodging Tolerance by using Pushing Resistance for Improving Rice Cultivar adapted to Direct Sowing Culture in Flooded Paddy Fields.

This study was undertaken to find the selection effectiveness of lodging tolerance by using pushing resistance for improving rice cultivar adapted to direct sowing culture in flooded paddy fields. The lines used in the experiment ware F4 and F5 breeding lines of Aoinokaze // Lemont / Hinohikari; 47 lines and Yumehikari // Lemont / Hinohikari; 29 lines that ware medium maturity lines. There was a significant negative correlation between the pushing resistance of F4 lines in transplanting culture and lodging degree of F5 lines in direct sowing culture. Even though the selection rate of pushing resistance in F4 was changing from 10% to 40%, thre was a distinct difference in lodging degree under direct sowing culture in F5. A few F5 lines selected by using pushing resistance in transplanting culture ware superior in lodging tolerance and yielding ability under direct sowing culture. There ware comparatively few deviations of yielding ability and grain quality by using pushing resistance for the selection of lodging tolerance in an early generation. These results lead to the conclusion that it is possible to breed high lodging tolerance cultivar adapted to direct sowing culture by using pushing resistance under transplanting culture in an early generation.

Model development and behavioral assessment of focal cerebral ischemia in rats

Stroke in humans is usually focal and occurs in the Middle Cerebral Artery (MCA) distribution. There are several rat models that mimic strokes clinically seen in human. Severity of ischemia can be determined by occlusion time, arteries occluded i.e. MCA alone or combined with one or both Common Carotid Arteries (CCA), and/or location of the occlusion. In this study three focal cerebral infarctions (stroke) were induced for 90 and 120 minutes due to the occlusion of: the MCA alone (MCAo); MCA plus unilateral CCA (MCAo + 1CCAo); and MCA plus bilateral CCA (MCAo + 2CCAo). Histological parameters included infarct lesion size and hemispheric swelling. Since functional recovery of clinical deficits in stroke often correlates with the efficacy of anti-ischemic therapy, we focused on the behavioral recovery. We combined many sources to obtain comprehensive guidelines for clinical behavior evaluation. Tests included limb flexion, torso twisting, circling, lateral push resistance, beam balancing and walking, hindlimb placing, and inverted angle-board gripping. Occlusion lasting 90 minutes was found to have consistent and repeatable deficits. Results from our study demonstrate 120 minutes of occlusion produced a 60% morality rate and was therefore dropped. Body weight changes between groups showed that increased occlusion time produced more weight loss. Behavior changes indicated that MCAo + 2CCAo for 90 minutes demonstrated assessable and consistent clinical deficits for the screening of potential therapeutics.

Relationship between Root System Distribution and Lodging Resistance in DIPPS (direct sowing of paddy rice into puddled and leveled soil) : Characteristics which explain pushing resistance

Relationship between Root System Distribution and Lodging Resistance in DIPPS (direct sowing of paddy rice into puddled and leveled soil) : Characteristics which explain pushing resistance

Selection of Rice Lines Using SPGP Seedling Method for Direct Seeding

Lodging is a major cause of yield loss in the rice production systems using direct seeding. In this study, several characteristics of 80 F4 breeding lines and 10 check cultivars were examined in connection with lodging resistance to establish a technique suitable for screening a large number of lines efficiently for breeding rice for direct seeding. Experiments were conducted over a 2-year period in puddled wet-fields and in seed pack growth pouches (SPGP). Among the root parameters of SPGP seedlings, only root thickness had a significant positive correlation (r = 0.495**) with pushing resistance, which is the force to bend rice culm to a designated angle and is correlated with lodging resistance. The root thickness of SPGP seedlings was also positively correlated with root thickness in the field at 18 (r = 0.346**) and 30 (r = 0.512**) days after seeding. For selected lines and check cultivars, positive correlations were found between pushing resistance and culm thickness in the field (r = 0.809**), between pushing resistance and root thickness in SPGP (r = 0.694**). Culm length and panicle number were negatively correlated with pushing resistance (r=–0.454**, r=–0.563**, respectively). Among the characteristics related to lodging, root and culm thickness were higher in selected breeding lines than in check cultivars. Grain yield was positively correlated with panicle weight (r = 0.601**) and harvest index (r = 0.586**) but not with panicle number (r=–0.007ns). Thus the low-tillering, panicle-weight type plants with thick roots and culms seem to be suitable for direct seeding. Some promising lines and candidate parental lines for the next crossing cycle for direct seeding were identified.

Studies on Direct Sowing Culture of Rice in Northern Kyushu. I. Evaluation of lodging tolerance.

北部九州において耐倒伏性を付与した直播用良食味品種を育成・選定するために, 湛水直播栽培における耐倒伏性の評価方法を検討した. 湛水直播栽培においては倒伏程度と稲体の支持力を表す押し倒し抵抗値とは相関が高く, 押し倒し抵抗値を用いて立毛状態で, 耐倒伏性の品種間差を評価できることが確認された. 湛水直播栽培における押し倒し抵抗値と移植栽培における押し倒し抵抗値の相関は高く, 移植栽培における押し倒し抵抗値と湛水直播栽培における倒伏程度の相関も高かった. したがって, 移植栽培条件下で押し倒し抵抗値を測定することにより, 湛水直播栽培条件下における倒伏程度を測定することが可能である. これらのことから, 耐倒伏性を付与した湛水直播用品種を育成する場合, 移植栽培条件下で押し倒し抵抗値を測定することにより, 直播栽培をせずに倒伏抵抗性の系統選抜が可能となり, 湛水直播用品種の育成・選抜の効率化が図られる.

Studies on Direct Sowing Culture of Rice in Northern Kyushu. II. Evaluation of lodging tolerance by crown root thickness during seedling stage.

This study was undertaken to find a method of evaluating lodging tolerance under direct sowing culture in flooded paddy field by the crown root thickness of seedlings for the selection of good eating quality rice cultivars well adapted to direct sowing in Northern Kyushu. The crown root thickness of seedling at 18 days after sowing showed a significant (p<0.01) positive correlation with the crown root thickness of thc plant at 15 days after heading under direct sowing culture. Also, crown root thickness of seedlings at 18, 20 and 30 days after sowing showed a significant (p<0.01, 0.05) negative correlation with lodging degree, and showed a significant (P<0.01, 0.05) positive correlation with the pushing resistance under direct sowing culture. On the other hand, there was no correlation between crown root thickness of seedlings at 10 or 12 days after sowing and lodging degree and pushing resistance. Furthermore, in the case of testing many good eating quality rice cultivars, crown root thickness of seedling at 30 days after sowing showed a significant (p<0.01) negative correlation with lodging degree and a significant (p<0.05) positive correlation with pushing resistance. In conclusion, we found that the lodging resistance of thc cultivars with thick roots at the seedling stage was generally resistant. This leads us to suppose the varieties with good eating quality adapted for direct sowing culture could be selected at the juvenile stage based on crown root thickness of seedlings.

A Portable Electronic Device for Evaluating Root Lodging Resistance in Maize

AbstractBecause climatic conditions conducive to natural lodging of maize (Zea mays L.) are sporadic and unreliable, a need exists for methods of evaluating the resistance of genotypes to root lodging. A portable electronic device was built for horizontal pushing resistance measurements on individual plants. The apparatus simultaneously records the angle of inclination and the resistance torque of the plant during an artificial pushing test. The device consists of a support, a force sensor, an angle sensor, and a control head. Data logging is possible by using a microprocessor‐based system. Data may be transferred to a computer using an RS232 serial transfer protocol. The time required for the test in field conditions is approximately 1 min per plant. Preliminary results obtained on 14 maize genotypes grown in three field environments showed that genotypes susceptible to root lodging were characterized by low average values of their maximum resistance torque.

Eco-physiological Characteristics Related with Lodging Tolerance of Rice in Direct Sowing Cultivation. III. Relationship between the characteristics of root distribution in the soil and lodging tolerance.

水稲における根の土壌中分布特性と耐ころび型倒伏性との関係を明らかにするために, 耐ころび型倒伏性程度の弱い日本の品種とこれの強いアメリカ合衆国の品種を用い, 断根処理, 作土下層への不織布埋設処理が押し倒し抵抗値に及ぼす影響を調査した. また, 土壌の充填密度をかえたポットで同じ材料を栽培し, 根重と押し倒し抵抗の上壌密度に伴う変動を調査した. 5cmの深さまでの浅い層に伸長する根を切断した場合の押し倒し抵抗の低下は比較的小さかったが, 10cmまで切断すると押し倒し抵抗が顕著に低下した. また, 5～10cmの深い部分の根が切断される場合, 単位根重あたりでみた押し倒し抵抗の低下度は, 5cmまでの断根処理に比べて大きい傾向が認められた. さらに, 作土下層に不織布を埋設すると, 押し倒し抵抗が低下する傾向がみられ, とくに心土層への根の分布量の多い品種ほど低下の程度が大きかった. 心土層中の根の単位根重当り押し倒し抵抗値は, いずれの品種においても作土層中の根に比べて大であった. 一方, 高密度で土壌を充填したポット内に生育した株は, 低密度で充填したポットの株より単位根重当りの押し倒し抵抗値が高くなった. 以上から, 水稲の耐ころび型倒伏性の改善には, 土壌密度の高い心土層へ根を多く分布させる特性が重要と判断された.

Eco-Physiological Characteristics Related with Lodging Tolerance of Rice in Direct Sowing Cultivation. I. Comparison of the root lodging tolerance among cultivars by the measurement of pushing resistance.

直播栽培における稲の耐ころび型倒伏性を生理生態的視点から解析する目的で, 地下部による株の支持力を品種間, 各種栽培法で比較した. 供試品種には移植条件で育成されてきた日本品種および半矮性インド型品種と直播条件下で育成されてきたアメリカ品種を用いた. 株支持力は上村らの手法に基づいて押し倒し抵抗を測定することにより推定した. 各品種の押し倒し抵抗ところび型倒伏の発生程度との間には負の相関関係がみられ, 耐ころび型倒伏性の評価における押し倒し抵抗測定の有効性が認められた. 栽培条件の押し倒し抵抗に対する影響については, 播種深度を1cmとして栽培した場合には地表面への播種に比べ, また, 水管理を間断潅漑で行うと常時湛水条件に比べてそれぞれ押し倒し抵抗が高まる傾向がみられた. 条間を一定とし, 条内の播種密度のみを変えた場合には, 播種密度の違いが押し倒し抵抗に及ぼす影響は小さかった. 品種間における押し倒し抵抗の差異は以上のような栽培方法の違いによる変動に比べて大きかった. アメリカ品種および穂重型の半矮性インド型品種は日本品種より高い押し倒し抵抗値を示し, ころび型倒伏程度もより軽微であった. 以上から, 直播水稲の耐ころび型倒伏性の改善のためには, 地下部による株支持力の育種的改良がより重要であることが示唆された.