Effects of Temperature and N Application Rate on Structural Matters of Cell Wall and Feed Quality of Italian Ryegrass
|School||Nanjing Agricultural College|
|Keywords||Italian ryegrass temperature structural matter of cell wall in vitro digestibility forage quality nitrogen application|
Italian ryegrass (Lolium multiflourum Lam.), which is a cool season grass, is one of the most useful and widely cultivated forage grass in southeastern China. It can be grazed, mowed, silaged and hayed. It’s yield and forage quality have been improved owing to breed improvement, culture techniques, management measures. With global warming and the expansion of planting area, the natural environment of palnt’s growth has been changed. And this change could have effect on yield and chemical structural component of Italian ryegrass.Nitrogen is an essential element to growth and development of Italian ryegrass. With increase of nitrogen application rate, crude protein (CP) content increased, utilization rate of N showed a downtrend. The palatability is more and more unfavorable with decreasing water soluble carbohydrate (WSC) content.The experiment included following two parts:1. The changes of cell wall structural matter contents, feeding qualities and the growth and development of early and late maturity lines of Italian ryegrass in field and Greenhouse were determined. The results showed:With the development of growing process, dry matter contents, heights, tiller amounts and cell wall structural matter contents of early and late maturity lines increased in field and Greenhouse. In vitro dry matter digestibility(IVDMD) decreased. WSC contents showed a low-high-low trend.WSC contents of early and late maturity lines reached the highest values at booting stage in field but at heading stage in Greenhouse..At different mowing dates, dry matter contents, tiller amounts and IVDMD of early and late maturity lines in Greenhouse were the lower than in field. Cell wall structural matter contents were contrary. WSC contents of early and late maturity lines in field were significant higher than in Greenhouse (P<0.05). During the prophase, higher temperature in Greenhouse accelerated lignifications. Feed qualities of early and late maturity lines in Greenhouse were the lower than in field, respectively. Compared with early maturity line, late maturity line kept higher feed quality.The correlation coefficients between cell wall structural matter content of stem and IVDMD of early and late maturity lines in field and Greenhouse were very negatively significant (P<0.01) or negatively significant (P<0.05). The correlation coefficients of between structural matter the content of cell wall structural matter and IVDMD at the prophase were greater than those at the anaphase.2. Early and late maturity lines of Italian ryegrass were used to study the effects on yields and feed qualities of regrowth under different nitrogen application rates. The results indicated:Dry matter yields, digestible dry matter yields, CP yields, CP contents and IVDMD of regrowth of Italian ryegrass increased with increase of nitrogen application rates, the contents of NDF, ADF, WSC reversed, WSC yields of most treatments showed no significant differences (P> 0.05).Under the same fertilizer rate, dry matter yield, digestible dry matter yield, CP yield, WSC yeild, WSC content and IVDMD of late maturity line of regrowth were higher than those of early maturity line; NDF and ADF content reversed.Dry matter yields, digestible dry matter yields, WSC and CP contents of regrowth of early and late maturity lines after the first cutting were higher than those after the second cutting, NDF and ADF contents reversed. The correlations between NDF, ADF, WSC contents and IVDMD were very negatively significant(P<0.01) or negatively significant(P<0.05). The correlation between CP contents and IVDMD were very postively significant (P<0.01) or postively significant(P<0.05).Utilization ratio of N was downtrend with increase of nitrogen application rate. In view of palatability, feed qualities and utilization rate of N, the favorable nitrogen application rate of early and late maturity lines were 300kg/hm2 in Nanjing.