Lucerne resources with different degree of resistance to root diseases
1999
Mistinova, A.
In the fifth year of vegetation 21 progenies of selected species of lucerne were tested for field resistance to root diseases (vascular wilt, dark crow necrosis and root rot) under stress conditions - compaction and frequent cutting. The plants were evaluated by a scale 0-6 (0=healthy) according to their symptoms on a cross-cut of the root. General state of stand health was expressed by the index 0-1 (1=healthy) which took into consideration the invasion of the root by diseases and closed stand at the same time. The stand was cut and compacted in four-week periods. Besides root diseases these yield characters were tested: yield (green mass weight), growth (closed stand, plant height and regrowth after cutting) as well a; the root morphology (root number, thickness, size). In the invasion of roots by diseases significant differences among progenies were found. Medicago sativa cv. Szarvasi (1. 19) was the least attacked. Medicago falcata (3.77) and Medicago sativa cv. Palava (4.78) were the most attacked. The significant interaction between compaction and progenies was an evidence of different reaction of progenies to compaction. The progenies of Medicago polychroa, Medicago hemicycla and Medicago sativa cv. Szarvasi (No. 15) with high values of the index (0.35 to 0.42) have good closed stand and proved resistance to diseases when exposed to compaction. Medicago trianschanica (No. 9) Medicago varia (No. 4) and Medicago sativa cv. Szarvasi (No. 16) - materials with high regrowth and closed stand values - showed high index (0.31 and 0.39) but intolerance to compaction. The index value (0.07 to 0.18) at Medicago sativa cv. Palava indicates low resistance to diseases at frequent cutting and compaction in the fifth year of vegetation
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