THE EFFECTS OF DIFFERENT WATER REGIMES ON GROWTH AND WATER USE EFFICIENCY IN SEEDLING STAGE OF SOME RICE VARIETIES (Oryza sativa L.

Transcription

1 J. Si. & Devel. 2014, Vol. 12, No. 3: Tạp hí Kho họ và Phát triển 2014, tập 12, số 3: THE EFFECTS OF DIFFERENT WATER REGIMES ON GROWTH AND WATER USE EFFICIENCY IN SEEDLING STAGE OF SOME RICE VARIETIES (Oryz stiv L.) Nguyễn Thị Ngọ Dinh 1*, Nguyễn Văn Lộ 1 nd Toshihiro Mohizuki 2 1 Fulty of Agronomy, Hnoi University of Agriulture; 2 Fulty of Agriulture, Kyushu University, Jpn Emil*: ntndinh@hu.edu.vn Reeived dte: Aepted dte: ABSTRACT Six rie (Oryz stivr L.) vrieties (Beodien, KD18, Koshihikri, Sensho, Ryd) were used to evlute genotypi vrition in growth nd wter use effiieny in the response to different wter regimes t seedling stge. Five dys fter sowing, seedlings were thinned to one plnt per pot nd wter tretments; flooding s ontrol, wellirrigted (24% Soil moisture ontent (SMC) (w/w)) nd drought (12% SMC) were pplied. The results of this experiment indited tht shoot dry weight (SDW), root dry weight (RDW), totl dry weight (TDW), lef re (LA), wter use (WU) nd wter use effiieny (WUE) of Ryd, Sensho, KD18 nd IR24 were not signifintly different etween ontrol nd well-irrigted onditions. Those of Koshihikri nd Beodien in well-irrigted were lower thn those in ontrol. In the eroi onditions (24% nd 12% SMC onditions), totl root length (RL), root surfe re (RSA) tended to inrese in lmost vrieties exept Koshihikri. RL, RSA nd root volume (RV) of Koshihikri in the eroi onditions were lower thn those in ontrol. Among vrieties used, Ryd hd the highest vlue in RL, RSA, RV, SDW, TDW, LA nd WU, followed y Sensho. Moreover, Ryd hd lso the highest vlue in WUE in drought onditions, followed y Sensho. Although KD18 nd IR24 hd lower vlues in LA, SDW, RDW, TDW, nd WU t ll tretments, these hrters were not severely ffeted y drought ompred with other vrieties. The results suggested tht Ryd nd Sensho re suitle with eroi rie system nd Koshihikri is not dptle. Indi lowlnd rie vrieties, KD18 nd IR24 my e desirle drought tolernt vrieties ompred with jponi lowlnd rie vriety, Koshihikri. Keywords: Drought, rie seedlings, soil moisture ontent. Ảnh hưởng ủ á độ ẩm đất khá nhu đến sinh trưởng và hiệu quả sử dụng nướ ủ một số giống lú (Oryz stiv L.) ở gii đoạn ây on TÓM TẮT Thí nghiệm nghiên ứu ảnh hưởng ủ độ ẩm đất đến á đặ điểm sinh trưởng và hiệu quả sử dụng nướ ở gii đoạn ây on ủ 6 giống lú (Oryz stivr L.) (Beodien, KD18, Koshihikri, Sensho, Ryd). 5 ngày su gieo hạt, tỉ để lại 1 ây ở mỗi hậu và ắt đầu xử lý độ ẩm đất với 3 mứ: đối hứng là ho ngập nướ; duy trì độ ẩm đất 24% (24%SMC)-độ ẩm tối ưu; độ ẩm đất 12% (12% SMC)-hạn. Kết quả ủ thí nghiệm hỉ r rằng, khối lượng hất khô ủ thân lá (SDW), khối lượng hất khô ủ rễ (RDW), tổng khối lượng hất khô ủ toàn ây (TDW), diện tíh lá (LA), lượng nướ sử dụng (WU) và hiệu quả sử dụng nướ (WUE) ủ 4 giống Ryd, Sensho, KD18, IR24 không ó sự si khá ó ý nghĩ 95% giữ ông thứ đối hứng và ông thứ độ ẩm đất 24%. Hi giống Koshihikri và Beodien ở ông thứ độ ẩm đất 24% ho giá trị thấp hơn so với ông thứ đối hứng đối với á hỉ tiêu trên. Ở ông thứ độ ẩm đất 24% và 12%, tổng hiều dài rễ (RL), diện tíh ề mặt rễ (RSA) ó khuynh hướng tăng ở hầu hết á giống trừ giống Koshihikri. RL, RSA, thể tíh rễ (RV) ủ giống Koshihikri trong điều kiện hảo khí thấp hơn ông thứ đối hứng. Giống Ryd đạt giá trị về RL, RSA, RV, SDW, TDW, LA và WU o nhất so với á giống òn lại, kế đến là giống Sensho. Ngoài r, giống Ryd òn đạt giá trị o nhất về hiệu quả sử dụng nướ (WUE) trong điều kiện hạn, kế đến là giống Sensho. Hi giống KD18, IR24 ó giá trị về LA, SDW, RDW, TDW và WU thấp 298

2 Nguyễn Thị Ngọ Dinh, Nguyễn Văn Lộ nd Toshihiro Mohizuki hơn so với á giống òn lại ở tất ả á ông thứ. Tuy nhiên, trong điều kiện hạn thì hi giống này không ị ảnh hưởng nhiều như á giống òn lại. Từ kết quả thí nghiệm ho thấy rằng hi giống Ryd, Sensho phù hợp với hệ thống nh tá hảo khí, giống Koshihikri không phù hợp. Giống lú nướ indi KD18 và IR24 thíh hợp với điều kiện hạn hơn giống lú nướ jponi Koshihikri. Từ khó: Độ ẩm đất, hạn, lú ở gii đoạn ây on. 1. INTRODUCTION Drought is one of the ritil prolems for griulture used y glol limti hnge. Drought hs een ffeting 20% of the totl rie-growing re in Asi (Pndey nd Bhndri, 2008). Rie prodution onsumes out 30% of ll freshwter used worldwide. In Asi, more thn 150 million hetres re irrigted nd ultivted re, menwhile 40-46% of rie rop is involved. At the field level, rie reeives more 2-3 times of wter thn other rops (Pndey et l., 2007). However, srity of freshwter hs thretened the prodution of the flood-irrigted rie rop (IWMI, 2000). Droughtprone re ws estimted t lest 20 perent totl rie re in Asi, this numer ws lso indited 10 perent in Vietnm (Pndey et l., 2007). Thus, reently, the rie prodution of Vietnm hs een seriously ffeted y drought. Rie (Oryz stiv L.) is sensitive rop to wter stress. Approximtely 50% of the rie prodution of the world is ffeted y drought (Boumn et l., 2005). Advned tehnologies development will mintin or inrese rie prodution in the fe of delining wter resoures. Reently, severl methods hve een found y griulturl sientists to redue wter loss nd inrese the wter produtivity of the rie plnt suh s lternte wetting nd drying (AWD) (Tl et l., 2002), ground over systems (Lin et l., 2002), system of rie intensifition (Stoop et l., 2002) nd new wter-sving tehnologies eroi rie systems (Boumn et l., 2005). Aeroi rie systems keep fields remining unsturted throughout the seson. George et l. (2002) showed tht the eroi onditions re known s free drining, non-flooded, nd nonpuddled soil with soil moisture ontent t elow sturtion. This method promises sustntil wter sving y minimizing seepge, peroltion nd gretly reduing evportion (Boumn et l., 2002). Mtsuo nd Mohizuki (2009) proved tht eroi rie systems ould sve more thn 47% of irrigtion wter in omprison with AWD. So, eroi rie system is one of promising dvned tehnologies to redue wter loss nd to inrese the wter produtivity of rie plnt. The present experiment is onduted y pplition this method with some modifitions. Besides new tehnologies, drought resistnt ultivrs should e onsidered to e those tht possess drought resistnt trits nd produe higher yield thn others under drought onditions. In Asi, uplnd rie is lredy grown eroilly with miniml inputs in the uplnd environment, ut lmost s low-yielding susistene rop to give stle yield (Lfitte et l., 2002). Uplnd rie vrieties re drought tolernt, ut hve low yield potentil. Besides, high-yielding lowlnd rie vrieties grown under eroi soil onditions, severely deresed yield. Boumn (2005) supposed tht eroi rie genotypes re new lsses of uplnd dpted genotypes with improving lodging resistne, hrvest index, input responsiveness nd tolerne to osionl flooding. These vrieties n omine the drought-resistnt hrteristis of uplnd vrieties with the high-yielding hrteristis of lowlnd vrieties (Lfitte et l., 2002). Previous studies of eroi rie systems hve foused on ompring morphologil nd physiologil trits suh s root prmeters, shoot dry weight, root dry weight, stomtl ondutne, yield nd yield omponents of eroi rie with those oserved under flooded pddy onditions (Boumn et l, 2005; Mtsuo nd Mohizuki, 2009; Mtsuo et l., 2009). This 299

3 The effets of different wter regimes on growth nd wter use effiieny in seedling stge of some rie vrieties (Oryz stiv L.) informtion is neessry for the seletion nd reeding of high-yielding eroi rie ultivrs in the future. However, there hs een only limited informtion in rop performne etween eroi nd flooded onditions. The ojetives of this study were to nlyze genotypi vrition in Growth nd WUE in the response to different wter regimes. 2. MATERIALS AND METHODS 2.1. Plnt mterils Six rie vrieties were used: two Vietnmese indi rie vrieties, Beodien (uplnd) nd KD18 (pddy); two jponi rie vrieties, Koshihikri (pddy) nd Sensho (uplnd); nd two indi pddy rie vrieties, IR24 nd Ryd Growth onditions The experiment ws onduted in Biotron of Fulty of Agriulture, Kyushu University with onstnt temperture t 25 0 C, 70% of humidity, 12h photoperiods nd 250μM m -2 s -1 of light intensity t dy time. Three pre-germinted seeds were sown in 1/10000 plsti pot ontined sndy ly lom soil (20.7% ly, 23.2% silt, nd 56.1% snd) with 12% of soil moisture ontent (SMC). We used 1/10000 Wgner pot with dimeter of 127mm nd height of 198mm (ICM, Tsuku) ontined with 1,0kg dried sndy ly lom soil with 2g hemil fertilizers (16%N : 16%P 2 O 5 : 16%K 2 O). The soil ws pre-mixed with fertilizer two dys efore sowing. The pots were rrnged in rndomized omplete design with 6 replitions for eh genotype y wter regime. In totl, 108 pots were used in the present experiment. Five dys fter sowing, seedlings were thinned to one plnt per pot nd wter tretments; flooding s ontrol, well-irrigted (24% SMC) nd drought (12%SMC) were pplied. The soil wter potentils of eh regime were 0kP, -1kP nd -53kP under ontrol tretment, 24% nd 12% SMC tretments, respetively. For determintion of soil wter potentil, the soil of eh regime ws well mixed with wter in plsti pot, nd the wter potentil of soil smple ws mesured using wtermrk model 900M- Monitor (IRROMETER COMPANY, INC, RIVERSIDE, CA). To void wter evportion from soil surfe, eh pot ws overed y expnded polystyrene ord with smll hole to llow seedling to grow. Wter ws dded every 2 dys to set the trget SMC Mesurements Four weeks fter sowing, seedlings were smpled. RL, RSA, RV, nd RD were nlyzed y using WinRHIZO (Regent Instrument In.). Lef re (LA) ws mesured with n AAM-8 lef re meter (Hyshi Denko Co. Ltd., Tokyo, Jpn). Shoot dry weight (SDW) nd root dry weight (RDW) were determined fter drying in n oven t 80 o C for three dys. Wter uptke (WU) rte ws determined y weighing pots every two dys nd WU during the tretments nd wter use effiieny (WUE, totl dry weight/wu) were lulted Dt nlysis Anlysis of vrine ws performed with different sttistil tests in Unistt v. 5.6 softwre (Unistt Ltd., London, UK). Dt were sujeted to Tukey s test to ompre men vlues t the 5% level of signifine. 3. RESULTS 3.1. Plnt growth Shoot dry weight Figure 1 shows SDW of six vrieties under three wter regimes t the end of the experiment. Ryd showed the highest in SDW t ontrol nd well-irrigted tretments, followed y Sensho. SDW of Ryd, Sensho, IR24 nd KD18 were not signifint different etween flooded nd well-irrigted onditions. But those of Koshihikri nd Beodien in wellirrigted ondition were lower thn those in 300

4 Nguyễn Thị Ngọ Dinh, Nguyễn Văn Lộ nd Toshihiro Mohizuki flooded ondition. SDW of KD18 nd IR24 were lower vlue t ll tretments thn other vrieties ut t drought ondition SDW of them were not severely ffeted ompred with other vrieties Root dry weight Figure 2 shows RDW of six vrieties under vrious wter regimes. There were no signifint different in RDW etween ontrol nd 24% SMC tretments of Ryd, Sensho, KD18 nd IR24. While s, those of Koshihikri nd Beodien t 24% SMC tretment were signifintly smller thn those t ontrol tretment. RDW of Beodien hd the highest vlue t flooded ondition with g/plnt, followed y Sensho t the sme tretment with g/plnt (Tle 1). KD18 hd the smllest in RDW t ll tretments. Interestingly, KD18 nd IR24 were smller in RDW t ll tretments thn other vrieties ut those vlues hd no hnge etween flooded nd drought tretment Totl dry weight TDW of six vrieties under different wter regimes is indited in figure 3. TDW of lmost ll vrieties did not signifintly hnge etween flooded nd well-irrigted onditions exept Beodien nd Koshihikri. Ryd hd the highest in TDW t ontrol nd 24% SMC tretments with g/plnt nd g/plnt, respetively (Tle 1). IR24 nd KD18 were lower in TDW ompred with other vrieties t ll tretments ut there were little derese etween flooded nd drought tretments ompred with other vrieties Lef re Lef re of six vrieties under vrious wter regimes re oserved in Figure 4. LA of ll vrieties hd signifintly lower t drought tretment ompred with other tretments. Ryd showed fster LA development thn other vrieties in ontrol nd 24% SMC tretments. LA of Ryd t ontrol tretment hd the highest vlue with m 2 (Tle 1). There ws not signifint hnge in LA etween flooded nd well-irrigted tretments of Ryd, Sensho, IR24 nd KD18 exept Beodien nd Koshihikri. IR24 nd KD18 hd smller in LA t ll tretments thn other vrieties ut those vlues were not severely ffeted y drought ondition ompred with other vrieties Wter uptke Figure 5 shows WU of six vrieties under three wter regimes. WU of ll vrieties t drought ondition hd nerly the sme vlue. WU of Ryd, Sensho, IR24 nd KD18 did not signifintly hnge etween ontrol nd 24% SMC tretments. While tht of Beodien nd Koshihikri in well-irrigted tretment were smller thn those in ontrol tretment. Ryd showed the highest vlue in WU t flooded nd 24% SMC tretment with g/plnt nd g/plnt, respetively, followed y Sensho t flooded nd 24% SMC tretment with g/plnt nd g/plnt, respetively (Tle 2). WU of KD18 nd IR24 were smller vlue t ll tretments thn other vrieties ut it lso ws not severely ffeted y drought ondition ompred with other vrieties Wter use effiieny WUE of six rie vrieties under three wter regimes re shown in figure 6. All vrieties t drought ondition hd higher in WUE thn those t flooded nd well-irrigted onditions. WUE of lmost vrieties hd no hnge etween ontrol nd 24% SMC tretments exept Koshihikri nd Beodien. WUE of Beodien nd Koshihikri were smller in well-irrigted ondition thn those in flooded ondition. Ryd hd the highest in WUE t drought tretment, followed y Sensho t the sme tretment Root morphologil trits Tle 3 shows root morphologil trits suh s totl root length, root surfe re, root volume nd rood verge prmeter of six vrieties in seedling stge under vrious wter regimes. 301

5 The effets of different wter regimes on growth nd wter use effiieny in seedling stge of some rie vrieties (Oryz stiv L.) Totl root length RL of lmost vrieties tended to inrese in the eroi onditions (24% SMC nd 12% SMC onditions) exept Koshihikri. Koshihikri in eroi onditions hd derese of 18.82% nd 21.40%, respetively, ompred with flooded ondition. Ryd hd the highest RL t drought nd well-irrigted onditions with m nd m, respetively, followed y Sensho t drought nd wellirrigted onditions with m nd m, respetively. Interestingly, KD18 nd IR24 hd muh higher RL t drought ondition with 87.67% nd 52.59%, respetively higher ompred with flooded ondition Root surfe re Exept Koshihikri nd Beodien, lmost vrieties were signifintly inresed in RSA t well-irrigted tretment s ompred with its orresponding vlues t flooded tretment. RSA of lmost vrieties tended to inrese t drought ondition ompred with flooded ondition exept Koshihikri. Koshihikri shrply deresed in eroi onditions (well-irrigted nd drought onditions) with 35.32% nd 28.81% redution, respetively. Ryd lso ws the highest in RSA t drought nd wellirrigted onditions, followed y Sensho with m 2 nd m 2 for Ryd, respetively nd m 2 nd m 2 for Sensho, respetively. Interestingly, RSA of KD18 nd IR24 hd muh higher t drought ondition thn those t other tretments with 81.89% nd 49.51%, respetively, s higher ompred with flooded tretment Root volume RV of Koshihikri nd Beodien tended to derese t eroi onditions (24% nd 12% SMC tretments). While s, other vrieties t well-irrigted nd drought tretments hd higher in RV thn those t ontrol tretment. Interestingly, RV of KD18 nd IR24 t 12% SMC tretment hd mrkedly inresed with 75.67% nd 46.68%, respetively higher ompred with those t ontrol tretment. Sensho t well-irrigted ondition nd Ryd t flooded nd well-irrigted onditions hd the highest in RV with 1.716m 3, 1.714m 3 nd 1.674m 3, respetively Root verge dimeter Tle 3 indites tht RD of KD18 nd IR24did not signifintly hnge etween flooded nd eroi onditions. Other vrieties were signifintly different in RD t drought ondition ompred with flooded ondition. Beodien t flooded ondition ws the highest in RD with 0.39 mm, followed y Sensho t ontrol nd well-irrigted tretments with the sme mgnitude of 0.35mm. RD of Ryd, Sensho, KD18 nd IR24 were not signifintly different etween well-irrigted nd flooded onditions, ontrry to those of Beodien nd Koshihikri t well-irrigted ondition were signifintly lower thn those t flooded ondition. 4. DISCUSSION In this experiment, Ryd, Sensho, IR24 nd KD18 did not signifintly hnge in SDW, RDW, TDW, LA, WU nd WUE etween flooded nd well-irrigted onditions. While s, those of Koshikri nd Beodien hd smller in wellirrigted tretment thn those in ontrol tretment (Fig 1-6). In ddition, RL nd RSA of lmost vrieties in eroi onditions (24% SMC nd 12% SMC onditions) tended to inrese exept Koshikri (Tle 3). RL, RSA, RV, SDW, RDW, TDW, LA nd WU of Koshihikri in eroi onditions were lower thn those in flooded ondition. The results suggest tht the root tivity of Koshihikri deresed in eroi onditions, espeilly in drought ondition. Therefore, it might e diffiult for the root systems of Koshihikri to ext enough soil wter, explining the signifintly lower WU, TDW, LA under eroi onditions. It ws proved tht Koshihikri might e ffeted severely y eroi onditions, espeilly in drought ondition. The results were onformed to the previous results (Mtsuo nd Mohizuki, 2009; Mtsuo et l., 2010). 302

6 Nguyễn Thị Ngọ Dinh, Nguyễn Văn Lộ nd Toshihiro Mohizuki Among vrieties used, Ryd showed the highest vlue in RL, RSA, RV, SDW, RDW, TDW, LA nd WU, followed y Sensho (Fig 1-5). Moreover, Ryd hd lso the highest vlue in WUE in drought ondition, followed y Sensho (Fig. 6). Therefore, in this study indites tht Ryd nd Sensho n dpt well to eroi rie systems (well-irrigted ondition) nd drought ondition. So, Ryd nd Sensho re promising ultivrs for eroi rie systems (Mstuo nd Mohizuki, 2009). KD18 nd IR24 hd smller in SDW, RDW, TDW, LA, WU t ll tretments ompred with other vrieties, these hrters were not severely ffeted y drought ompred with other vrieties. Interestingly, RDW of KD18 nd IR24 hd no hnge etween flooded nd drought onditions. Furthermore, KD18 nd IR24 hd muh higher in RL, RSA nd RV t drought ondition thn those t other tretments with 87.67%, 81.89% nd 75.67% for KD18, respetively nd 52.59%, 49.51% nd 46.68% for IR24, respetively higher ompred with flooded ondition (Tle 3). It ws proved tht indi lowlnd rie vrieties, KD18 nd IR24 my e desirle drought tolerne vrieties ompred with jponi lowlnd rie vrieties, Koshihikri. My Mtsunmi et l. (2012) suggested tht some lowlnd ultivrs hve high dptility to uplnd onditions, s long s dequte soil moisture is mintined, omprle to tht under flooded ondition. In this experiment, three lowlnd ultivrs Ryd, KD18, IR24 n e dpt well to wellirrigted ondition. Kondo (2000) reported tht wter uptke in rie delined mrkedly under severe drought stress ompred with mild stress, wheres wter uptke in mize ws similr t two stress levels, possily due to the deeper root growth tht ws oserved in mize. In this study, WU of six vrieties t drought ondition were signifintly deresed ompred with flooded nd wellirrigted onditions (Fig. 4). Dry mtter prodution ility of rie under drought ondition ws reted y high ility of trnspirtion (= wter uptke), ut not y high WUE (Kot et l., 1996). Generlly, defiient soil moisture uses redution of trnspirtion, resulting in n inrese in WUE without inresing iomss prodution (Blum, 2005). Wter uptke ws the highest in ontrol tretment of ll vrieties, so TDW of ll vrieties were lso the highest in ontrol tretment nd the smllest in drought tretment. But WUE of six vrieties were the highest vlue t drought ondition. Following to Mtsuo et l. (2010), the WUE vlues for Sensho nd Beodien in wter sving tretment were more thn 20% higher thn in well-irrigted tretment, wheres Koshihikri were only 86% of the vlues in wter sving tretment. In this present study, WUE of Koshikri t well-irrigted tretment ws less thn tht t drought ondition. It proved tht t erly seedlings stge, WUE of Koshihikri tended to e higher in drought ondition. Wter uptke y plnts is strongly dependent on the morphologil nd physiologil ttriutes of roots. Regrding rie root morphologil, whih is dptle to flooded onditions, Ymuhi et l. (1988) speulted tht those ultivrs with onentrted type of root system, whih owns lrge numer of short individul rown roots, might e more dptle to flooded ondition, due to suh root system might e supplied dequte oxygen to the root pex to promote ell division. In this study, Ryd hd the highest in RL, RSA, RV nd WU, followed y Sensho. Furthermore, Ryd hd lso the highest in WUE t drought ondition, followed y Sensho. So, they re suitle with eroi onditions. The present study showed tht t drought stress signifintly differed in root system development, s shown y RL, RSA, RV nd RD (Tle 3). The sme results were found y ABD Allh, A.A., et l. (2010); Mtsuo N. nd Mohizuki T. (2009) nd Mtsuo et l. (2010) y using other genotypes. In this experiment, RL 303

7 The effets of different wter regimes on growth nd wter use effiieny in seedling stge of some rie vrieties (Oryz stiv L.) nd RSA tended to inrese in the eroi onditions (24% nd 12% SMC tretments) in lmost vrieties exept Koshihikri. Among vrieties used, Ryd hd the highest vlue in RL, RSA nd RV, followed y Sensho (Tle 3). Oski et l. (1997) suggested tht high root tivity seures high photosyntheti rte y supplying suffiient mount of nutrients to shoot, thus ensure high produtivity. So, Ryd nd Sensho n sor more wter to supply to shoot to produe iomss. In this study, SDW, TDW nd LA of Ryd hd the highest vlue, followed y Sensho (Fig. 1-3). Fst growth of SDW during the erly growth stge my e desirle trit under eroi rie systems from the viewpoint of ompetition etween rie plnts nd weeds. Thik roots re lso hypothesized to onfer drought tolerne euse root rnhing is relted to root thikness (Fitter, 1991). Thik roots persist longer nd produe more nd lrger root rnh, therey inrese root length density nd wter uptke pity (Ingrm et l., 1994). Tle 3 displys tht RD of Ryd, Sensho, KD18, IR24 were not signifintly different etween ontrol nd well-irrigted tretment, so they ould hve the greter ility to extrt wter nd keep wter potentil high y soring wter due to they hd high vlue of desirle root trits relting to drought voidne mehnism. It proved tht Ryd, Sensho, KD18 nd IR24 n dpt with wellirrigted ondition. Menwhile, RD of Beodien nd Koshihikri were mrkedly deresed y eroi onditions reltive to those in flooded ondition. In ddition, SDW, RDW, TDW, LA, WU nd WUE of Koshihikri nd Beodien in well-irrigted tretment were lower thn those in ontrol tretment. So, Koshihikri nd Beodien were not suitle with eroi onditions, even though in well-irrigted ondition. Previous studies reported tht jponi uplnd rie vrieties hd thiker roots thn indi ones under eroi onditions (Mtsuo N. nd Mohizuki T., 2009). In the present study, uplnd rie Beodien nd Sensho hd higher root verge dimeter thn tht in lowlnd rie t flooded nd eroi onditions nd jponi uplnd rie (Sensho) ws higher in RD thn indi one (Beodien) under eroi onditions. 5. CONCLUSION SDW, RDW, TDW, LA, WU nd WUE of Ryd, Sensho, KD18 nd IR24 were not signifint different etween well-irrigted nd flooded onditions. Those of Beodien nd Koshihikri in well-irrigted ondition were lower thn those in flooded ondition (Fig. 1-6). In eroi onditions (24% nd 12% SMC tretments), RL nd RSA of lmost vrieties tended to inrese exept Koshihikri. RL, RSA, RV of Koshihikri in eroi onditions were lower thn those in flooded ondition (Tle 3). In onlusion, Ryd, Sensho, IR24 nd KD18 n dpt with well-irrigted ondition ut Koshihikri nd Beodien is not dptle. In ddition, Ryd nd Sensho re suitle with eroi rie systems. Interestingly, indi lowlnd rie vrieties, KD18 nd IR24 hve desirle trits for drought tolernt vrieties ompred with jponi lowlnd rie vriety, Koshihikri. Further study is neessry to find differenes in root hrters suh s root hydruli ondutne, quporin nd physiologil mehnism to respond wter uptke nd wter use effiieny of rie under different wter regimes. 304

8 Nguyễn Thị Ngọ Dinh, Nguyễn Văn Lộ nd Toshihiro Mohizuki Tle 1. The effets of different wter regimes on shoot dry weight (SDW), root dry weight Vriety (RDW), totl dry weight (TDW) in seedling stge of some rie vrieties Tretment Shoot dry weight (g/plnt) Root dry weight (g/plnt) Totl dry weight (g/plnt) Lef re (m 2 ) Ryd Control (-) (-) (-) (-) 24% SMC (94.93%) (103.27%) (96.29%) (94.75%) 12% SMC (38.36%) (73.22%) (43.81%) (36.45%) Sensho Control (-) (-) (-) (-) 24% SMC (105.45%) (91.75%) (102.90%) (102.02%) 12% SMC (40.31%) (65.46%) (49.30%) (53.43%) KD18 Control (-) (-) (-) (-) 24% SMC (92.04%) (87.34%) (91.54%) (90.22%) 12% SMC (70.32%) (105.06%) (75.55%) (62.52%) IR24 Control (-) (-) (-) (-) 24% SMC (96.08%) (98%) (96.38%) (93.03%) 12% SMC (53.48%) (93%) (57.92%) (43.22%) Beodien Control (-) (-) (-) (-) 24% SMC (61.24%) (45.97%) (58.22%) (64.49%) 12% SMC (43.78%) (46.92%) (42.35%) (46.70%) Koshihikri Control (-) (-) (-) (-) 24% SMC (50.23%) (38.61%) (48.41%) (43.27%) 12% SMC (35.79%) (32.27%) (35.25%) (33.40%) Note: Men vlue ± stndrd devition SMC mens soil moisture ontent (w/w). Men within olumn followed y the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s Test (n=6) 1,2 Shoot dry weight (g/plnt) 1 0,8 0,6 0,4 0,2 0 Ryd Sensho KD18 IR24 Beodien Koshihikri Control 24% SMC 12% SMC Fig. 1. The effets of different wter regimes on shoot dry weight in seedling stge of some rie vrieties Note: SMC mens soil moisture ontent (w/w). Brs with the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s test (n=6). 305

9 The effets of different wter regimes on growth nd wter use effiieny in seedling stge of some rie vrieties (Oryz stiv L.) Root dry weight (g/plnt) 0,25 0,2 0,15 0,1 0,05 0 Ryd Sensho KD18 IR24 Beodien Koshihikri Control 24% SMC 12% SMC Fig. 2. The effets of different wter regimes on root dry weight in seedling stge of some rie vrieties Note: SMC mens soil moisture ontent (w/w). Brs with the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s test (n=6). Totl dry weight (g/plnt) 1,4 1,2 1 0,8 0,6 0,4 0,2 0 Ryd Sensho KD18 IR24 Beodien Koshihikri Control 24% SMC 12% SMC Fig. 3. The effets of different wter regimes on totl dry weight in seedling stge of some rie vrieties Note: SMC mens soil moisture ontent (w/w). Brs with the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s test (n=6) 306

10 Nguyễn Thị Ngọ Dinh, Nguyễn Văn Lộ nd Toshihiro Mohizuki Lef re (m 2 ) Ryd Sensho KD18 IR24 Beodien Koshihikri Control 24% SMC 12% SMC Fig. 4. The effets of different wter regimes on lef re in seedling stge of some rie vrieties Note: SMC mens soil moisture ontent (w/w). Brs with the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s test (n=6). Tle 2. The effets of different wter regimes on wter use (WU) nd wter use effiieny (WUE) in seedling stge of some rie vrieties Vriety Tretment Wter uptke (g/plnt) Wter use effiieny (g DW/g H 2O) Ryd Control (-) (-) 24% SMC (97.14%) (99.50%) 12% SMC (30.29%) (145.02%) Sensho Control (-) (-) 24% SMC (109.63%) (97.37%) 12% SMC (35.02%) (147.37%) KD18 Control (-) (-) 24% (93.09%) (99.16%) 12% (52.38%) (143.29%) IR24 Control (-) (-) 24% SMC (100.03%) (98.51%) 12% SMC (41.62%) (139.28%) Beodien Control (-) (-) 24% SMC (71.74%) (83.33%) 12% SMC (35.08%) (123.80%) Koshihikri Control (-) (-) 24% SMC (56.49%) (83.72%) 12% SMC (26.07%) (116.27%) Note: Men vlue ± stndrd devition SMC mens soil moisture ontent (w/w). Men within olumn followed y the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s Test (n=6) 307

11 The effets of different wter regimes on growth nd wter use effiieny in seedling stge of some rie vrieties (Oryz stiv L.) 350 Wter use (g/plnt) Ryd Sensho KD18 IR24 Beodien Koshihikri Control 24% SMC 12% SMC Fig. 5. The effets of different wter regimes on wter use in seedling stge of some rie vrieties Note: SMC mens soil moisture ontent (w/w). Brs with the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s test (n=6). 7 Wter use effiieny (mg DW /gh 2 O) Ryd Sensho KD18 IR24 Beodien Koshihikri Control 24% SMC 12% SMC Fig. 6. The effets of different wter regimes on wter use effiieny in seedling stge of some rie vrieties Note: SMC mens soil moisture ontent (w/w). Brs with the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s test (n=6). 308

12 Nguyễn Thị Ngọ Dinh, Nguyễn Văn Lộ nd Toshihiro Mohizuki Tle 3. The effets of different wter regimes on totl root length (RL), root surfe re (RSA), root volume (RV) nd root verge dimeter (RD) in seedling stge of some rie vrieties Vriety Tretment Length(m) Are (m 2 ) Volume (m 3 ) Dimeter (mm) Ryd Control (-) (-) (-) (-) 24% SMC (129.27%) (130.34%) (131.24%) (100.63%) 12% SMC (146.75%) (137.19%) (128.17%) (93.12%) Sensho Control (-) (-) (-) (-) 24% SMC (130.34%) (129.59%) (128.44%) (100%) 12% SMC (117.92%) (109.70%) (101.79%) (92.09%) KD18 Control (-) (-) (-) (-) 24% SMC (111.52%) (106.87%) (102.40%) (96.71%) 12% SMC (187.67%) (181.49%) (175.67%) (96.71%) IR24 Control (-) (-) (-) (-) 24% SMC (122.56%) (122.18%) (121.73%) (100.65%) 12% SMC (152.59%) (149.51%) (146.68%) (98.02%) Beodien Control (-) (-) (-) (-) 24% SMC (113.17%) (85.94%) (65.27%) (76.65%) 12% SMC (142.82%) (109.37%) (83.48%) (77.16%) Koshihikri Control (-) (-) (-) (-) 24% SMC (81.18%) (64.68%) (51.54%) (79.41%) 12% SMC (78.51%) (71.19%) (64.55%) (91.17%) Note: Men vlue ± stndrd devition SMC mens soil moisture ontent (w/w). Men within olumn followed y the sme letter in eh vriety re not signifintly different t P<0.05 y Tukey s Test (n=6) REFERENCES Ad Allh, A.A., et l. (2010). The role of root system Trits in the drought tolerne of rie (Oryz stivr L.). World Ademy of Siene, Engineering nd Tehnology 68. Boumn, B.A.M., Wng, H., Yng, X., Zho, J., Wng, C. (2002). Aeroi rie (Hn Do): new wy of growing rie in wter-short res. In: Proeedings of the 12 th Interntionl Soil Conservtion Orgniztion Conferene, My, 2002, Bejing, Chin. Tsinghu University Press, pp Boumn, B.A.M., S. Peng, A.R. Cstoed nd R.M. Vispers. (2005). Yield nd wter use of irrigted tropil eroi rie systems. Agriulturl Wter Mngement, 74(2): Fitter, A.H. (1991). Chrteristis nd funtions of root systems. In: Y. Wisel, A. Eshel nd U. kfkfi eds., Plnt Roots - The Hidden Hlf. Mrel Dekker, New York George, T., Mgnu, R., Grrity, D.P., Tun, B.S., Quiton, J. (2002). Rpid yield loss of rie ropped suessively in eroi soil. Agron. J. 94: Kot, T., Okuno, T. nd Ymmoto, T. (1996). Contriutions of pity for soil wter extrtion nd wter use effiieny to mintenne of dry mtter prodution in rie sujeted to drought. Jpn. J. Crop Si. 64: Ingrm, K.T.; Bueno, F.D; Nmuo, O.S.; Ymo, E.B nd Beyrouty, C.A. (1994). Rie root trits for drought resistne nd their geneti vrition. IRRI, Philippines. In G.J.D Kirk ed., Rie roots. Nutrient nd Wter Use IWMI. (2000). Interntionl Wter Mngement Institute (IWMI), IWMI Glol Wter Srity Study. Interntionl Wter Mngement Institute, Colomo, Sri Lnk. Lfitte, R et l. (2002. Geneti improvement of rie in eroi systems: progress from yield to genes. Field Crops Reserh 75: Lin, S., Dittert, K., Sttelmher, B. (2002). The Ground Cover Rie Prodution System (GCRPS)- 309

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