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vi ron ments and higher per sis tence in these stands. ..... Lamb J. F. S., Barnes D. K., Henjum K. I. (1999): Gain from two cy cles of di ver gent se lec tion.
Original scientific paper

VARIABILITY OF ALFALFA ROOT MORPHOLOGY AMONG CZECH ALFALFA VARIETIES IN THE SEEDING YEAR Josef Hakl, Jaromír [antru~ek, Ladislav Krajíc, Svobodová Milu{e Department of forage crops and grassland management, Czech university of agriculture Prague, Kamýcká 957, 165 21 Prague 6 - Suchdol, Czech republic

Summary: The root morphology of alfalfa is connected to many important agronomic traits but few investigations have focused on European varieties. The goal of this study was to screen the variability of root morphology among several alfalfa varieties in the seeding year. In this experiment ten varieties of alfalfa (nine Czech varieties and Europe) were analyzed for selected root morphological parameters after excluding stand density effect. Our results from seeding year show that although significant differences could be detected between the evaluated varieties these differences were small. Cluster analysis showed that the major differences between the varieties were in depth of the first branching point, lateral root number and root diameter. Experimental data indicates lateral root number is inversely correlated with the depth of the first branch point. This preliminary study is being continued to investigate more fully the main differences between varieties in the following years. Key words: alfalfa, variety, root morphology.

INTRODUCTION Generally, the alfalfa morphology strongly influences its characteristics. Kati} et al. (2003) reported that the morphological characteristics of alfalfa are significantly correlated with yield and dry matter quality. According to many authors, the alfalfa root morphology is a very important agronomic trait compared to the morphology of above ground biomass. Johnson et al. (1998) concluded that root system morphology has a role in plant persistency and Lamb (2000) showed that the productivity of lucerne was influenced by root morphology. Bliss (2003) reported that shallower and more branched root systems are positively correlated with tolerance to poor soil conditions, better growth in a variety of environments and higher persistence in these stands. Root morphology traits are heritable, but morphology is also strongly influenced by dormancy and geographic origin (Lamb et al., 1999). [antru~ek (1988) concluded that in addition to the effect of genotype, the degree of alfalfa root branching was influenced by the term of stand establishment, stand density, and soil compaction. The effect of stand density on alfalfa root morphology was confirmed by Hakl et al. (2007). In this experiment Hakl used Jarka and several new cultivars of alfalfa and showed that tap-root diameter was positively correlated with lateral root number and diameter and all of these variables were negatively correlated with the stand density. The effect of stand density was significant and explained about 15 % of measured parameters variability. 39

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Institut za ratarstvo i povrtarstvo, Novi Sad

It is therefore seems likely that root morphological parameters are important traits and are connected with agronomic characteristics. There are few investigations reported in the literature which have compared the root morphology of European alfalfa varieties. We now report the results of an experiment at the Department of Forage Crops and Grassland Management which investigated root morphology in ten alfalfa varieties (nine Czech national varieties and Europe) during a seeding year.

MATERIALS AND METHODS The plot experiment with evaluated varieties was established in the field of the Research station of the Czech University of Agriculture in ^ervený Újezd in spring 2006. The mean annual temperature at this location is 7.7 oC and the long-term annual sum of precipitation is 493 mm. The prevailing soil type is clay loam orthic luvisol and the kind of soil is medium with the neutral soil reaction. The following varieties were used: Pálava, Morava, Vlasta, Magda, Jarka, Zuzana, Jitka, Niva, Oslava, and Europe. The plot experiment was of completely randomized design with eight replicates for each variety. The plants were sampled in autumn from area 330 x 330 mm in each plot; the average depth of sampling was 150 mm. The number of plants per m2 was determined. The following parameters were measured for each individual plant: tap-root diameter under the crown (TD), lateral root number (LRN), lateral root diameter (LRD), and lateral root position (LRP - a depth of the first branch). These morphological parameters were statistically evaluated by analysis of covariance (ANCOVA) where stand density was used as covariate. Values of LRN, LRD, and LRP could only be taken from branching plants. The TD value, intensity of branching (IB = lateral root number per each measured plant), and percentage ratio of branching plants (RBP) were measured for all measured plants. For evaluation of similarity among evaluated varieties we used cluster analysis. All statistical analysis were performed using Statistica 6.0 (StatSoft, Tulsa, OK, USA)

RESULTS AND DISCUSSION As expected stand density significantly influenced morphological parameters, which is in accordance with results of Hakl et al. (2007). For the purpose of analysis we excluded the effect of density by including it as a covariate and all results reported in this paper have been therefore normalised for this effect. The means and variability of measured parameters are shown in table 1 and 2. Based on table 1 and 2, we conclude that the lowest variability was assessed for tap-root diameter with coefficient of variation (CV) from 4.8 to 6.0 %. In contrast, the highest CV was observed for IB where CV ranged from 9.2 to 16.1 %. The average CV for RBP, LRD, LRN, and LRP were 8.4, 6.3, 9.2, and 10.2 %, respectively. The lowest average CV was for variety Magda (7.2 %) and the highest for variety Europe (9.8 %). The highest differences in CV among varieties were for IB, RBP, LRP and LRN. The p-value indicates that significant differences could be detected between varieties for all morphological parameters except for LRP. The p-value is proximate due to lower extent of data set. Johnson et al. (1998) compared 1067 alfalfa entries and described the highest LRN by falcata and x varia entries. The average LRN class in their experiment was from 8 to 11 LRN. In

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comparison with their results, the differences we detected between varieties were not high. Based on measured values, all evaluated varieties belong among sativa entries in accordance with Johnson et al. (1998). Table 1. Mean values and coefficient of variation (CV) of TD (tap-root diameter), IB (intensity of branching), and RBP (percentage ratio of branching plants) at evaluated alfalfa varieties in seeding year. N represents a number of evaluated plants. variety Pálava Morava Vlasta Magda Jarka Zuzana Jitka Niva Oslava Europe p-value

TD mean (mm) 6.99 6.40 5.74 6.11 6.47 5.97 6.39 5.77 6.06 6.72 0.0143

CV 4.99 5.40 6.03 5.09 4.84 5.20 5.00 4.83 4.69 6.14

IB mean (pcs) 2.43 1.88 1.39 2.20 1.63 1.49 2.15 1.55 1.38 1.83 0.0001

CV 9.36 11.99 16.15 9.21 12.50 13.58 9.66 11.70 13.42 14.68

RBP mean (%) 69 56 64 71 62 54 61 56 43 65 0.0021

CV 7.73 9.36 8.22 6.71 7.75 8.80 8.02 7.64 10.10 9.73

N 91 80 80 98 97 99 93 123 126 58

Table 2. Mean values and coefficient of variation (CV) of LRD (lateral root diameter), LRP (lateral root position), and LRN (lateral root number) at branching plants of evaluated alfalfa varieties in a seeding year. N represents a number of evaluated plants. variety Pálava Morava Vlasta Magda Jarka Zuzana Jitka Niva Oslava Europe p-value

LRD mean (mm) 2.48 2.10 2.13 2.11 2.07 2.20 2.12 2.11 2.37 2.49 0.0191

CV 6.04 7.01 6.47 5.76 6.22 6.38 6.34 5.91 6.43 6.33

LRP mean (mm) 36.07 32.76 40.78 36.71 42.85 31.45 32.47 43.75 37.93 37.53 0.5059

CV 11.13 12.02 9.02 8.84 8.04 11.94 11.08 7.62 10.74 11.23

LRN mean (pcs) 3.58 3.28 2.19 3.17 2.68 2.90 3.56 2.85 2.87 2.82 0.0017

CV 8.10 8.65 12.10 7.38 9.26 9.33 7.28 8.43 10.23 10.79

N 51 47 54 69 61 52 56 66 45 42

We used the cluster analysis for similarity comparison of evaluated varieties. In the first step, the hierarchical method showed three main clusters at distance four. In the second step, we used k-means method with three defined clusters. These results are displayed in table 3. The differences between the clusters were mainly due to differences in LRP, LRD and LRN. It can be concluded that the varieties Vlasta, Jarka, and Niva from cluster 1 branch at a deeper point and these varieties have a comparatively small number of lateral roots which are generally of smaller diameter (low LRN and LRD). In contrast, the varieties Morava, Zuzana, and Jitka branch at a shallower point and have a comparatively

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Institut za ratarstvo i povrtarstvo, Novi Sad

greater number of lateral roots (high LRN). The varieties Pálava, Vlasta, Oslava and, Europe belong to cluster 2 with intermediate LRP, LRN, and highest observed LRD value. It seems that the value of LRN increases with decreasing depth of the first branch point. According to Lamb et al (2000), densely seeded plants need more time to show maximum expression of root traits and consequently these scored lower for LRN and had smaller TD than spaced plants. If this is so we can not assume that observed differences in root morphology between varieties in the seeding year is the highest and definitive. Table 3. Results of cluster analysis by k-means method for TD (tap-root diameter), IB (intensity of branching), RBP (ratio of branching plants), LRD (lateral root diameter), LRP (lateral root position), and LRN (lateral root number). P-value represents differences among clusters.

TD (mm) IB (pcs) RBP (%) LRD (mm) LRP (mm) LRN (pcs)

cluster 1 mean SD 5.99 0.41 1.53 0.12 61 4 2.10 0.03 42.46 1.52 2.58 0.34

members

Vlasta, Jarka Niva

cluster 2 mean SD 6.47 0.46 1.96 0.46 62 13 2.36 0.18 37.06 0.83 3.11 0.35 Pálava, Magda, Oslava, Europe

cluster 3 mean SD 6.25 0.25 1.84 0.34 57 4 2.14 0.05 32.23 0.69 3.25 0.33

p-value 0.3394 0.3288 0.7766 0.0503 0.0000 0.0976

Morava, Zuzana, Jitka

CONCLUSIONS Our results of alfalfa root morphology from seeding year show that difference among evaluated varieties could be detected in almost all evaluated traits but measured values and their variability indicated only small differences that were within sativa limits. The differences between the groups of varieties were mainly in the depth of the first branching, lateral root number and diameter. It seems that LRN value increased with decreasing depth of first branching. The main differences between the varieties could not be determined in the seeding year thus experiment will be continued. These results provide knowledge about differences between alfalfa varieties in these traits as well as providing preliminary data to help improve the methodological procedure of root morphological evaluations.

ACKNOWLEDGEMENTS Research was supported by Ministry of Education, Youth and Sport of the Czech Republic by Project MSM 6046070901

References Bliss R. M.(2003): Flowering Alfalfa breaks barriers. Agricultural Research. October, 10, 8 - 10 Hakl J., [antru~ek J., Kalista J., Kocourková D. (2007): The root morphology of new lucerne candivar. Scientia Agriculturae Bohemica, 38, 1 - 5.

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Johnson L.D., Marquez-Ortiz J., Lamb J. F. S., Barnes D. K. (1998): Root morphology of alfalfa plant introductions and cultivar. Crop-Science. March-April, 38, 497-502. Kati} S., Mihailovi} V., Karagi} w., Mili} D., Pataki I. (2003): Yield, morphology and chemical composition of five lucerne genotypes as affected by growth stage and the environment. Grassland science in Europe, 8, 376 - 379. Lamb J. F. S., Barnes D. K., Henjum K. I. (1999): Gain from two cycles of divergent selection for root morphology in alfalfa. Crop-Science, 39, 1026-1035. Lamb J.F.S., Johnson L.D., Barnes D.K., MARQUEZ-ORTIZ J.J. (2000): A method to characterize root morphology traits in alfalfa. Canadian Journal of Plant Science, 80, 97-104. [antru~ek J. (1988): Vliv zhutnìní pudy na utváøení koøenové soustavy vojtì{ky ve 2. a 3. roce vegetace. Sborník V[Z v Praze, fakulta agronomická, øada A, 48, 311-327.