and there were no significant differences between cv. RvP and Bb 1277.The results are discussed in relation to the breeding potential of the high nutritive value of the Po valley ecotype Bb 1277 and the use ofthe DMD and FI determinations for selecting for improved herbage quality in Italian ryegrass.The influence of harvesting date on the nutritive value of the Italian ryegrass cv. RvP from Belgium and of Bb 1277, an introduced ecotype from the Po valley, was investigated.Ten clonally replicated genotypes of each population were grown as closely spaced plants and two ramets of each genotype harvested every 4 d for a period of 28 d after inflorescence emergence. Dry matter digestibility (DMD) was estimated and fibrosity index (FI) determined on both the leaf and stem fractions, and cellulose and lignin concentrations were determined on the stem fractions.The nutritive value of the leaf in terms of both DMD and FI, which was the same for both cv. RvP and Bb 1277 throughout the period of harvesting, was always higher and declined at a slower rate with increasing maturity than that of the stem. The stem of Bb 1277 declined in DMD and increased in FI and cellulose concentration at a significantly slower rate than cv. RvP. Significantly higher levels of DMD were detected in the stem of Bb 1277 for harvests 5 to 8 and significantly lower levels of FI and cellulose concentration from harvests 4 to 8. It was not, however, possible to detect any significant diflerences in stem lignin concentration. Dry matter yields increased throughout the period of harvesting
Harper, J. A., Thomas, I. D., Lovatt, J. A., Thomas, H. M. (2004). Physical mapping of rDNA sites in possible diploid progenitors of polyploid Festuca species. ? Plant Systematics and Evolution, 245, (3-4), 163-168Festuca species form a polyploid series but only two of the diploid species have been firmly proposed as progenitors of any polyploid. The number and distribution of rDNA sites on the chromosomes of F. scariosa (section Scariosae) and the four diploid species that comprise section Montanae are presented with their relative DNA amounts and key morphological features. Comparisons of the results with those of some polyploid Festuca species from section Bovinae published previously indicate that F. scariosa and F. altissima could be diploid progenitors of the polyploids. It is unlikely that any one of the other three Montanae species is a progenitor of these polyploids.Peer reviewe
Aim Magnesium (Mg) deficiency (known as grass tetany) is a serious metabolic disorder that affects grazing ruminants. We tested whether Mg-fertiliser can increase Mg concentration of Italian ryegrasses (Lolium multiflorum L.) including a cultivar (cv. Bb2067; 'Magnet'), bred to accumulate larger concentrations of Mg. Methods Under controlled environment (CE) conditions, three cultivars (cv. Bb2067, cv. Bb2068, cv. RvP) were grown in low-nutrient compost at six fertiliser rates (0-1500 μM MgCl 2 .6H 2 O). Under field conditions, the three cultivars in the CE condition and cv. Alamo were grown at two sites, and four rates of MgSO 4 fertiliser application rates (0-200 kg ha −1 MgO). Multiple grass cuts were taken over two-years. Results Grass Mg concentration increased with increasing Mg-fertiliser application rates in all cultivars and conditions. Under field conditions, cv. Bb2067 had 11-73% greater grass Mg concentration and smaller forage tetany index (FTI) than other cultivars across the Mg-fertiliser application rates, sites and cuts. Grass dry matter (DM) yield of cv. Bb2067 was significantly (p < 0.05) smaller than cv. Alamo. The effect of Mgfertiliser rate on DM yield was not significant (p ≥ 0.05). Conclusions Biofortification of grass with Mg through breeding and agronomy can improve the forage Mg concentration for grazing ruminants, even in highgrowth spring grass conditions when hypomagnesaemia is most prevalent. Response to agronomic biofortification varied with cultivar, Mg-fertiliser rate,
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