Printer Friendly

Downy mildew reaction of alfalfa accessions of different geographical origin under Lithuanian conditions.

Byline: Aurelija Liatukiene and 1/2ilvinas Liatukas

Abstract

Study was conducted during 20092011 under field conditions with natural infection at the Institute of Agriculture located in central part of Lithuania. The alfalfa (Medicago sativa L.) downy mildew (caused by Peronospora trifoliorum) resistance was evaluated on 100 accessions originating from distinct countries across the world. Wet weather conditions were highly favourable for alfalfa downy mildew resistance investigations. Accessions were compared by maximal disease severity (DS) and area under disease progress curve (AUDPC). Disease development was very intensive in 2009 when DS ranged from 880% and AUDPC value ranged 1401938. DS but not AUDPC values was lower in 2010 DS ranged from 6.345% and AUDPC ranged 203-2123. The lowest disease development determined in 2011 when DS ranged 1.817.5% and AUDPC ranged 40266. The relatively stable disease development on accessions possessing different resistance was indicated by medium to very strong (r=0.587 0.932 ) correlation coefficients between DS and AUDPC across years. Origin of the host accessions showed considerable impact on resistance. According to data of 2009 resistant and medium resistant (DS up to 10 and 20% respectively) accessions accounted for 7 and 13% respectively. The majority of the most resistance accessions originated from neighbouring countries characterized by similar to Lithuanian cool temperate climate. Copyright 2014 Friends Science Publishers

Keywords: Medicago sativa; Resistance; Peronospora trifoliorum

Introduction

Alfalfa (Medicago sativa L.) is widely grown over the world as a perennial forage crop due to its good quality and high herbage yield. This species presents large diversity for various traits since it is cultivated in contrasting environments (Julier et al. 2000). The recent trend of increasing prices for fertilizers especially nitrogen will force to increase cultivation area of forage legumes. However deficiency of high complex disease resistance is one of the main constrains for successful cultivation of alfalfa durable crop (Lamb et al. 2006).Alfalfa is one of the most yielding perennial legume grasses in Lithuania also (Slepetys 2008) but growing area compose small share among total area of grasses (Anonymous 2012b). The recent investigation of alfalfa disease resistance in Lithuania showed that broad range of diseases can heavily damage all plant parts of alfalfa in Lithuania (Liatukiene and Liatukas 2010). The highest negative impact diseases make on seed yield (Liatukiene2012). It is the soundest reason why alfalfa area is so insignificant in Lithuania and neighbouring countries of the Baltic Sea region (Anonymous 2012a). Whereas under dry hot climate conditions alfalfa produces high seed yields (Rashidi et al. 2009).Downy mildew caused by Peronospora trifoliorum deBy. is harmful disease of alfalfa in the temperate climate areas. The most efficient mean to control disease is growing of resistant cultivars. Investigations of alfalfa resistance to fungal diseases showed that material of different origin were considerably different by resistance to downy mildew (Jie et al. 2000; Yaege and Stuteville 2000). Genetic peculiarities of resistance to P. trifoliorum were comprehensively investigated in studies of Skinner and Stuteville (1985;1988). Availability of genetically diverse alfalfa material allows developing of alfalfa cultivars improved by disease resistance (Nagl et al. 2011).Study of Lamb et al. (2006) showed that cultivars yielding improvement during 50 years of breeding was very environment depending. The main advantage of new cultivars was multiple disease resistance. Whereas the gain in forage yields improvement was only 0.1-0.2% per year.Information about alfalfa cultivars resistance to downy mildew in Europe is scanty only some indirect studies are available. Comprehensive recent research including considerable number of accessions was not found. Therefore the present study aimed to determine the downy mildew resistance of geographically different alfalfa accessions under cool temperate climate conditions of Lithuania.Materials and Methods

Plant Material and Field Design

Research was conducted at the Institute of Agriculture of Research Centre for Agriculture and Forestry in the field of a six-course crop rotation of forage grasses in experimental years 2009-2011. The soil of the experimental site is Endocalcari-Endohypogleyic CambisolC Mg-n-w-can (pH 7.2-7.3 P2O5 201-270 mg kg-1 and K2O 101-175 mg kg-1 humus 2.0-2.46%). Nursery was maintained undernatural infection pressure. Alfalfa nursery was established after a black fallow without a cover crop in the first decade of July in 2009. The complex phosphorus and potassium fertiliser was applied once before sowing at the rate P60K90. Every accession was sown at a rate 0.2 g scarified seed per 1 meter in two 5-metre long rows in three replications with special hand-sowing machine Plotmatic 1R produced byWintersteiger Austria. The distance between the rows of a line was 0.5 m; the distance between different lines was 1.0 m. The nursery was used as a seed crop. The experimental material composed of 100 accessions of alfalfa of different geographical origin (Table 2). The plots were sprayed with mix of herbicide Basagran 480 (2 L ha1) (active ingredient bentazon 480 g L-1) and insecticide Karate Zeon 5 CS (0.2 L ha-1) (active ingredient lambda-cihalotrin 50 g L-1) when alfalfa after germination reached the height of 10 cm in2009. The herbicide Fenix SC 600 (3 L ha1) (active ingredient aklonifen 600 g L-1 was applied in spring after resumption of vegetation in 2010 and 2011. The insecticide Karate Zeon 5 CS was applied when pests became harmful in 2010 and 2011.

Evaluation of Resistance

Downy mildew was evaluated in 2009-2011. Disease severity (DS) was evaluated during all season by using the scale: 0 0.1 1 5 10 20 40 60 and 80% (Campbell and Madden 1990). The resistance level of accessions was compared by maximal DS in 2009 that varied from 8.0 to80.0%. Accessions evaluated by DS up to 10.0% were considered asresistant (R) greater than 10.020.0% as medium resistant (MR) greater than 20.040.0% as medium susceptible (MS)greater than 40.060.0% as susceptible(S) and over 60.0% as highly susceptible (HS).

Weather Conditions

Weather conditions during experimental period are presented in Table 1. Rains were very abundant in 2009; alfalfa crop establishment was very even and vigorous. All three years had more than usual precipitations during vegetation period. It was very favourable for disease development. January was very cold with weak snow cover in 2010. Nonetheless alfalfa over wintering was very good. Overwintering was weak in some accessions in 2011 due to heavy show cover that favoured development of Sclerotinia crown and root rot.

Results

Development of Downy Mildew

The downy mildew was the first disease that started after renewal vegetation of alfalfa. However its development later was stopped by other diseases in 20102011 especially by spring black stem and leaf spots (causal agent Phoma medicaginis var. medicaginis) (Table 2). Fig. 1 shows the downy mildew development on three alfalfa genotypes considerably differing in AUDPC values in 2009-2011. The downy mildew severity constantly decreased from 2009 to 2011. AUDPC values among the most resistant and susceptible alfalfa genotype differed about 10- fold from 159 to 1820 and 218 to 2123 in 20092010 respectively. The difference among AUDPC values was about 5-fold from 49 to 219 in 2011. Maximal disease severity among alfalfa genotypes differed similarly. Severe downy mildew development on susceptible cultivars in2009 during couple of months after sowing shows excellent possibility to test alfalfa resistance in relatively short terms. Also it shows high aggressiveness of disease and its potential of harmfulness. Low disease severity in resistant cultivar (8.0 6.8 and 1.8% in 20092011 respectively) shows sound impact of the resistant cultivars use in the control of downy mildew.

Alfalfa Downy Mildew Reaction

The accessions presented in Table 3 are sorted in ascending order of maximal downy mildew severity in 2009. The alfalfa accessions differed considerably in downy mildew severities. The screening revealed similar differentiation of alfalfa resistance when DS and AUDPC values were compared in all years. The both values can be used to estimate alfalfa resistance. However calculation of AUDPC values can be done only after several DS assessments. On the other hand downy mildew development (Fig. 1) in 20092011 showed necessity to evaluate disease development as longer as possible. Maximal DS was registered in different disease development periods. This value was registered at the last assessment in 2009 and 2011 and at the second assessment in 2010.

Table 1: Precipitations and temperature in 20092011 (Lithuania Akademija weather station)

Month###Precipitations mm###Temperature (C)

###2009 2010 2011 1924-###2009 2010 2011 1924

###2011###2011

January###41.0 18.6 39.4 30.2###-2.8 -10.8 -3.2 -4.8

February 18.7 36.9 18.8 25.3###-3.5 -4.3 -7.8 -4.5

March###53.9 22.1 9.5###28.5###0.9###0.0###0.0###-0.8

April###13.1 44.2 15.6 36.9###8.9###7.3###8.8###5.8

May###26.7 94.2 46.8 52.0###12.7 13.7 13.0 12.3

June###168.6 72.4 44.3 62.4###14.6 16.2 18.1 15.7

July###90.0 142.0 115.0 73.4###18.1 21.7 19.7 17.7

August###67.1 71.1 103.8 73.7###16.8 19.8 17.4 16.7

September 48.2 52.1 54.0 51.0###13.9 11.9 13.7 12.0

October###95.4 38.0 23.9 50.2###5.2###5.0###7.6###6.8

November 63.5 71.1 21.7 44.3###3.9###3.2###3.9###1.8

December 49.9 59.6 36.2 37.2###-2.5 -7.5 1.9###-2.3

Table 2: Diseases of alfalfa in 20092011

Disease###Year

###2009###2010###2011

Downy mildew###+++###++###++

Spring black stem and leaf spot###+###+++###+++

Sclerotinia crown and root rot###-###+###++

The maximal DS ranged from 8.0 to 80.0 6.3 to 35.0 and1.8 to 17.5% in 20092011 respectively. The AUDPC values ranged from 140 to 1838 203 to 2123 and 40 to 266 in 2009-2011 respectively.Origin of the host accessions showed considerable impact on resistance. Alfalfa accessions are compared by results of 2009 due to the highest differentiation of alfalfa accessions downy mildew resistance in 2009. KAlppen-Geiger climate zone classification (Peel et al.2007) was only partially applicable for grouping of alfalfa accessions by downy mildew resistance. The resistant (7%) and medium resistant (18%) accessions originated from Lithuania and neighbouring countries with wet and cool weather. Only cultivars Romagnola (R) and Picweeh (MR) originated from geographically distinct countries (Italy and Canada respectively) characterized by rather dry weather during plant vegetation. The medium susceptible accessions (13%) group contained cultivars originated from countries which can be characterized as similar to above mentioned. The sound difference regarding geographical origin was clear in the group of susceptible accessions (30%). Only about a third of accessions originated from countries with rather cool and wet climate. The rest two thirds originated from countries characterized by rather or clearly dry and warm or hot weather. The highly susceptible accessions (32%) originated from countries characterized by rather or clearly dry and warm or hot weather. Some exception can be accessions PI 214218 (Denmark) PI577507 and PI 502485 (Germany). However the main reason for this exception should be old development data of these accessions.The correlations between DS and AUDPC results of accessions across years varied from medium to very strong (r=0.587 0.932 ) (Table 4). The correlations between DS and AUDPC of the same year were strong to very strong (r=0.838 0.932 ).The correlations between DS of different year as well as AUDPC were medium to strong (r=0.654 0.741 and 0.587 0.816 respectively). The same tendency was calculated for correlations between DS and AUDPC of different years (r=0.625 0.822 ).

Discussion

Development and severity of downy mildew and cultivars differentiation shows that Lithuanian climate is very favourable for alfalfa resistance investigations.

Table 3: Maximal severities and AUDPC values of downy mildew in alfalfa accessions in 20092011

Alfalfa###Country###Maximal disease###AUDPC value

accession###of origin###severity %

###2009 2010 2011###2009###2010###2011

Antan###LT###8.0 a 6.3a 1.8ab###159ab###218ab###48ab

Radius###PL###8.0a 10.0ab 2.8b###159ab###279a-c###62bc

Nadezhda II###RU###10.0ab 10.0ab 1.8ab###140a###279a-c###62bc

Zydrn###LT###10.0ab 6.3a 1.8ab###178ab###218ab###50b

Birut###LT###10.0ab 6.3a 1.8ab###178ab###203a###58b

Vertus###SE###10.0ab 8.8ab 5.0c###194a-c###252a-c###106de

Romagnola###IT###10.0ab 6.3a 1.8ab###230bc###240ab###48ab

Bayard###FR###12.0a-c 8.8ab 1.8ab###159ab###247ab###50b

Malvina###LT###12.0a-c 6.3a 1.8ab###197a-c###203a###50b

Karlu###EE###12.0a-c 6.3a 1.8ab###197a-c###224ab###44ab

Saartepola###EE###12.0a-c 10.0ab 6.3c###197a-c###365cd###67bc

Augn###LT###12.0a-c 8.8ab 1.0a###253bc###246ab###40a

Vorksla###RU###12.0a-c 8.8ab 1.8ab###285bc###262a-c###52b

Bella###NL###12.0a-c 17.5cd 5.0c###286bc###414de###122fg

Resis###DK###18.0b-d 10.0ab 2.8b###271bc###388c-e###67bc

Lucia###SK###18.0b-d 10.0ab 2.8b###305bc###279a-c###77b-d

Janu###NL###18.0b-d 12.5bc 5.0c###314b-d###382c-e###143g-i

Jurlu###EE###20.0cd 10.0ab 1.8ab###273bc###393c-e###44ab

Tagamorsa###EE###20.0cd 10.0ab 6.3c###273bc###376c-e###67bc

Luna###BE###20.0 cd 8.8ab 2.8b###290bc###322b-d###61b

Magda###CZ###20.0cd 17.5cd 5.0c###324b-d###416de###118fg

Bagira###RU###20.0cd 8.8ab 2.8b###326b-d###248ab###67bc

Jogeva 118###EE###20.0cd 10.0ab 1.8ab###326b-d###352cd###44ab

Vela###DK###20.0cd 8.8ab 1.8ab###362b-d###263a-c###62bc

Picweeh###CA###20.0cd 8.8ab 1.8ab###362b-d###288bc###52b

Mazhotnes###BY###25.0de 10.0ab 2.8b###337b-d###388c-e###67bc

Niva###CZ###25.0de 10.0ab 2.8b###344b-d###352cd###94d

Orca###FR###25.0de 17.5cd 5.0c###371cd###421de###71b-d

Kunsmme###EE###25.0de 10.0ab 1.8ab###377cd###283a-c###44ab

Vilsana###EE###25.0de 12.5bc 5.0 c###377cd###325b-d###60b

Jarka###CZ###25.0de 12.5bc 2.8b###410c-e###340cd###73b-d

Viktorija###CZ###35.0e-g 10.0ab 5.0c###439c-e###302b-d###106de

Morova###CZ###35.0e-g 8.8ab 1.8ab###466de###288a-c###63bc

Ellerskie I###CA###35.0e-g 6.3a 1.8ab###468de###240ab###48ab

EerikSaare###EE###35.0e-g 10.0ab 6.3c###470de###310b-d###67bc

Magali###FR###35.0e-g 12.5bc 2.8b###472de###466ef###77b-d

Palava###CZ###35.0e-g 10.0ab 5.0c###482d-f###312b-d###108ef

Semira###RU###35.0e-g 35.0f 8.8d###505d-f###1084ij###143g-i

Marija Odd.###UA###45.0fg 8.8ab 2.8b###527ef###295bc###63bc

Luzelle###FR###45.0fg 17.5cd 2.8b###527ef###445d-f###68bc

Abruka###EE###45.0fg 12.5bc 6.3c###528ef###334cd###76b-d

Verko###HU###45.0fg 10.0ab 1.0a###534ef###319b-d###40a

Mireille###FR###45.0fg 25.0e 5.0c###563e-g###567f-h###193i-k

Algongnin###CA###45.0fg 17.5cd 2.8b###567e-g###459d-f###67bc

Commandor###USA###45.0 fg 10.0ab 2.8b###600e-g###336cd###77b-d

PI 206283###TR###45.0fg 35.0f 6.3c###600e-g###833hi###162hi

Zuzana###CZ###45.0fg 8.8ab 2.8b###621fg###297bc###84 cd

PI 422567###RU###45.0fg 20.0d 12.5e###626 fg###833hi###189ij

Bobrava###CZ###45.0fg 17.5cd 2.8b###793hi###416de###111ef

Creno###DK###45.0fg 35.0f 2.8b###793 hi###681gh###72b-d

Kardla###EE###55.0hi 10.0ab 2.8b###655f-h###354cd###49b

Jitka###CZ###55.0hi 17.5cd 2.8b###658 f-h###416de###77b-d

Sitel###NL###55.0hi 17.5cd 1.8ab###722gh###414de###45ab

Alfagraze###CA###55.0hi 10.0ab 2.8 b###726gh###331cd###73b-d

Europe###FR###55.0hi 12.5bc 2.8b###860ij###356cd###67bc

Sigma###RO###55.0hi 17.5cd 8.8d###881ij###588f-h###116fg

PI 211609###AF###55.0hi 35.0f 8.8d###1211lm###1867m###145g-i

PI 467888###USA###55.0hi 35.0f 8.8d###1358l-n###1204jk###108ef

Plauresa###DE###60.0i 12.5bc 6.3c###709gh###538fg###85cd

Belfeuil###FR###60.0i 17.5cd 2.8b###742g-i###435d-f###88cd

Sandra###RO###60.0i 17.5cd 6.3c###742g-i###588f-h###108ef

Magnat###RO###60.0i 17.5cd 6.3c###775hi###490e-g###95d

Vertibenda###PL###60.0i 25.0e 8.8d###874ij###836hi 130fg

Polder###FR###60.0i 20.0d 2.8b###885ij###526fg 90cd

Derby###NL###60.0i 20.0d 2.8b###885ij###465ef###68bc

Mandolina###RO 60.0i 20.0d 8.8d###885ij###563f-h 98de

PI 573153###CN 60.0i 35.0f###6.3c 1025j-l 968h-j 172h-j

Elda###EE###60.0i 12.5bc 6.3c 1155k-m 465ef###67bc

Daniela###RO 65.0ij 20.0d 6.3c###717gh 520e-g 107de

Kosmina###RO 65.0ij 20.0d 6.3c 750g-i 526fg 107ef

Natsuwakaba###JP###65.0ij 17.5cd 8.8d###75g-i###66gh 142gh

Luxin###RO 65.0ij 20.0d 5.0c###790hi 603f-h 124fg

PI 499547###CN 65.0ij 35.0f 10.0d 1037j-l 1135i-k 204i-k

Alina###RO 65.0ij 25.0e 6.3c 103 j-l 765g-i 101de

PI 467980###USA 65.0ij 35.0f###8.8d 1230lm 1134i-k 110ef

Pulav###UA 75.0j-l 12.5bc 8.8d###796hi 563f-h 172h-j

Tin Jin###CN 75.0 j-l 35.0f###8.8d 918i-k 1304j-l 132gh

Szarvasi###HU 75.0 j-l 25.0e 8.8d 1017j-l 769g-i 120fg

Mediterranea###ES 75.0 j-l 35.0f###6.6c 1060j-l 1012h-j 83cd

PI 452463###CA 75.0j-l 35.0f 10.0d 1136k-m 1072ij 178ij

PI 214218###DK 75.0j-l 35.0f###8.8d 1160k-m 975h-j 143g-i

PI 577507###GE 75.0j-l 20.0d 6.3c 1160k-m 848hi 143g-i

PI 452444###USA 75.0j-l 25.0e 12.5e 1308k-m 1084ij 139gh

PI 502485###GE 75.0j-l 35.0f###6.3c 1318k-m 988h-j 118fg

PI 467916###USA 75.0j-l 35.0f###8.8d 1655mn 1195 i-k 123fg

PI 467899###USA 75.0j-l 35.0f###6.3c 1755no 1315 j-l 95d

Adin###RO 80.0kl 17.5cd 5.0c###860ij###568f-h 97de

PI 577514###RU 80.0kl 25.0e 6.3c 899i-k 945h-j 162hi

PI 467895###USA 80.0kl 25.0e 6.3c 932i-k 1162i-k 108ef

Katinka###RO 80.0kl 25.0e 5.0c###965jk###663gh 154hi

PI 212104###AF 80.0kl 35.0f 10.0d 1094kl 1438 kl 191i-k

PI 573153###CN###80.0kl 35.0f 17.5g 1097kl 1523k-m 266jk

PI 577460###PK 80.0kl 45.0h 8.8d 1160k-m 1589lm 175h-j

PI 467910###USA 80.0kl 25.0e 8.8d 1180k-m 786g-i 127fg

PI 467901###USA 80.0kl 25.0e 10.0d 1180k-m 786g-i 126fg

Rancap###PE 80.0kl 35.0f###5.0c 1573mn 1004h-j 87cd

PI 467965###USA 80.0kl 35.0f###6.3c 1703no 1207i-k 137gh

PI 440539###KZ 80.0kl 45.0h 17.5g 1820n-p 2123n 219i-k

PI 467922###USA 80.0kl 35.0f 10.0d 1820n-p 1066ij 133gh

PI 449316###CN 80.0kl 35.0f 12.5e 1838n-p 1165i-k 178ij

Average###47.4 19.4###5.4###724.8 621.8###100.6

However this situation negatively influences alfalfa growing in Lithuania. Seed production inside country is very limited and its multiplication abroad greatly increases seed price and this in turn decreases growing areas. Foreign alfalfa cultivars grown without previous testing are in most cases heavily damaged by diseases which even more raises mistrust of farmers in alfalfa.Downy mildew was very harmful disease to susceptible accessions tested. One of disease peculiarities is that causal agent overwinters in plants and starts to develop and spread after resumption of vegetation (Hanson 1998). Usually it damages top of plants. When infection is severe very susceptible plants can be destroyed completely just after regrowth in spring.

Table 4: Correlation among downy mildew disease severities (DS) and AUDPC values in 20092011

Traits###2009-DS 2010-DS 2011-DS 2009-###2010-

###AUDPC###AUDPC

2010DS###0.741

2011DS###0.654 0.731

2009AUDPC 0.885 0.822 0.685

2010AUDPC 0.723 0.932 0.805 0.816

2011AUDPC 0.624###0.735 0.838 0.587###0.755

Top damage of plants made highly negative impact to seed production even under relatively low disease severity in 2010 and 2011 in all susceptible accessions. Seeds were not produced in 2010 at all due to higher downy mildew development. Resistance to this disease depends on combinations of mono and polygenes (Skinner and Stuteville 1988; 1989; Skinner and Stuteville 1992; Yaege and Stuteville 2000). Since alfalfa is cross pollinating plant it populations consists of plants which vary by resistance (Skinner and Stuteville 1985; 1989). In our case we did not find any accessions consisting of completely resistant individuals as well as in the study of Skinner and Stuteville (1992) with several hundreds of Medicago spp. accessions. However the most resistant accessions were damaged only up to 8.0% in 2009. It shows possibility to select individual plants with highest resistance across population and develop new improved populations. Development of new populations with considerably higher resistance level takes several selection cycles which can continue up to 10 and more years (Kanbe et al. 2002). Screening populations resistant at seedling stage can denote the most resistant seedlings (Yaege and Stuteville 2000). However disease agent can adapt to monogenes very rapidly. Therefore a more promising resistance breeding strategy should rely on accumulation of polygenes (Slusarenko et al. 2000). It means that selection should be relying on multiple assessment data received under field conditions. Greenhouse growing technology can be applied but it requires very high inputs. Lithuanian weather conditions are very favourable for P. trifoliorum spread and development as wet years are most common. Alfalfa nurseries should be established in the second part of summer avoiding dry weather of May and June as August and September are characterized by excessive precipitations and very abundant dew. Plants vegetation period during August and September is long enough for considerable disease development and further selection of resistant plants in populations. Seed will not mature at the same year but in any way selected plantsshould be evaluated for the 2nd season to evaluate resistance to Sclerotinia crown and stem rot (Sclerotinia trifoliorum) in spring as well as to spring black stem and leaf spotsduring summer. As only alfalfa cultivars possessingcomplex resistance to a range of pathogen can be successfully grown in wet and cool climate of the Baltic Sea countries.Our experimental data was in accordance with these studies. It means that geographically distinct accessions could hardly improve downy mildew resistance of Lithuanian or neighbouring countries alfalfabreeding material. It is serious constraint for introduction ofuseful traits such as tolerance to aluminium. Intensive alfalfa aluminium tolerance breeding is progressing across a range of countries (Scott et al. 2008; Vitorello et al. 2005). Very promising material is developed but in most cases it does not possess resistance to complex of diseases that are harmful in Baltic Sea region (Liatukiene 2012).In conclusion selection of the most diseases resistant plants from such material and later crossing with locally adapted material should enable introductions of such traits. The majority of Baltic Sea region alfalfa material was resistant or medium resistant to downy mildew. These alfalfa accessions can be used to improve downy mildew resistance in the other countries.

References

Anonymous 2012a. Fodder plants. Medicago sativa L. In: Common catalogue of varieties of agricultural plant species. Official J. Eur. Union 31: 132140Anonymous 2012b. Lithuanian Statistical Department. Available at http://db1.stat.gov.lt (Accessed: 02 April 2013)Campbell C.L. and L.V. Madden 1990. Introduction to Plant DiseaseEpidemiology. John Wiley and Sons New York USAHanson A.A. 1998. Alfalfa and alfalfa improvement. Amer. Soc. Agron. Madison Wisconsin USAJie L.C. N.Z. Biao W.Y. Wen and Y.R. Wang 2000. Evaluation for alfalfa germplasm resistance to downy mildew under AlpineGrassland conditions. Acta Prat. Sin. 9: 4451Julier B. C. Huyghe and C. Ecalle 2000. Within and among cultivar genetic variation in alfalfa: forage quality morphology and yield. Crop Sci. 40: 365369Kanbe M. Y. Mizukami and F. Fujimoto 2002. Improvement of resistance to Sclerotinia crown and stem rot of alfalfa through phenotypic recurrent selection. Jpn. Agr. Res. Q. 36: 15Lamb J.F.S. C.C. Sheaffer L.H. Rhodes R.M. Sulc D.J. Undersander and E.C. Brummer 2006. Five decades of alfalfa cultivars improvement: impact on forage yield persistence and nutritive value. Crop Sci.46: 902906Liatukiene A. 2012. Investigation of genetic diversity of lucerne (Medicago spp.) by identifying resistance to pathogen and mobile aluminium. PhD thesis Res. C. Agr. For. Akademija LithuaniaLiatukiene A. and 1/2. Liatukas 2010. Lucerne complexive resistance todiseases. Scripta Hort. Bot. Univ. Vyt. Mag. 14: 98104Nagl N. K. TaskiAjdukovic G. Barac A. Baburski I. Seccareccia D.Milic and S. Katic 2011. Estimation of the genetic diversity in tetraploid alfalfa populations based on RAPD markers for breeding purposes. Int. J. Mol. Sci. 12: 54495460Peel M.C. B.L. Finlayson and T.A. McMahon 2007. Updated world mapof the KAlppenGeiger climate classification. Hydrol. Earth Syst. Sci.11: 16331644Rashidi M. B. Zand and M. Gholami 2009. Effect of different seeding rates on seed yield and some seed yield components of alfalfa (Medicago sativa). Int. J. Agric. Biol. 11: 779782Scott B.J. M.A. Ewing R. Williams A.W. Humphries and N.E. Coombes2008. Tolerance of aluminium toxicity in annual Medicago species and lucerne. Aust. J. Agric. 48: 499511Skinner D.Z. and D.L. Stuteville 1985. Quantitatively inherited reactions of alfalfa to Peronospora trifoliorum. Phytopathology 75: 717721Skinner D.Z. and D.L. Stuteville 1988. Polygenes in diploid alfalfa thataffect resistance to downy mildew. Crop Sci. 28: 508511Skinner D.Z. and D.L. Stuteville 1989. Accumulation of minor gene resistance to Peronospora trifoliorum in diploid alfalfa. Phytopathology 79: 721724Skinner D.Z. and D.L. Stuteville 1992. Geographical variation in alfalfa accessions for resistance to two isolates of Peronospora trifoliorum. Crop Sci. 32: 14671470Slusarenko A.J. R.S.S. Fraser and L.C. van Loon 2000. Mechanisms of resistance to plant diseases Kluwer Academic Publishers Dordrecht NetherlandsSlepetys J. 2008. Productivity and persistence of pure and mixed forage swards. Latv. J. Agron. 11: 276282Vitorello V.A. F.R. Capaldi and V.A. Stefanuto 2005. Recent advances inaluminium toxicity and resistance in higher plants. Braz. J. PlantPhysiol. 17: 129143Yaege J.R. and D.L. Stuteville 2000. Reactions in the annual Medicago core germplasm collection to two isolates of Peronospora trifoliorum from alfalfa. Plant Dis. 84: 521524
COPYRIGHT 2014 Asianet-Pakistan
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2014 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Liatukiene, Aurelija; Liatukas, Zilvinas
Publication:International Journal of Agriculture and Biology
Article Type:Report
Geographic Code:4EXLT
Date:Oct 31, 2014
Words:4395
Previous Article:Medicinal plants after forest disturbance restoration and cultivation in Pakistani Himalaya.
Next Article:Molecular Classification of Pakistani Rose-Ringed Parakeet using Mitochondrial ND2 Gene.
Topics:

Terms of use | Privacy policy | Copyright © 2019 Farlex, Inc. | Feedback | For webmasters