西北旱区喷灌条件下紫花苜蓿生长特征与品质指标的关系

西北旱区由于独特的气候条件,生产的苜蓿干草品质好,产量高。如何根据苜蓿的田间指标估测干草品质参数,对于苜蓿草产品生产销售具有重要意义。研究在喷灌条件下不同灌溉量对紫花苜蓿的生长品质的影响,并利用生长指标对紫花苜蓿的品质进行预测。试验于2014至2015年于中国农业大学石羊河流域生态节水试验站进行为期2年的田间试验。试验共设3个灌溉处理:A₁灌溉量为100%紫花苜蓿蒸腾蒸散量(ETc),A₂,A₃的灌溉量分别为A₁处理的66%,33%,以及一个不灌溉处理A₄。结果表明,苜蓿生长指标如株高(H)和茎叶比(SLR)随生育期的推进呈上升趋势,而鲜干比(FDR)呈下降趋势;所有生长指标随着灌溉量的减少均呈下降趋势。在品质方面,随着生育期的推进,所有处理的粗蛋白(CP)呈下降趋势,而中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)则呈现上升趋势;随着灌溉量的降低,NDF与ADF呈下降趋势,而CP则呈上升趋势。各生长指标与品质指标的拟合结果表明,H和SLR均与各品质指标显著线性相关(P<0.001),且H与品质拟合结果相关系数最高(R²>0.900),而FDR则与各品质指标不显著。这些结果表明,在田间管理较好,长势良好,杂草与病虫害发生较少的情况下,可以用株高对苜蓿干草品质做出预测。

The relationship between growth characteristics and the quality of alfalfa under sprinkler irrigation in the northwest arid area of China

Estimating forage quality with field measurements is useful for alfalfa production. In order to investigate the prediction of quality from growth characteristics, this experiment studied the growth and quality of alfalfa under different sprinkler irrigation levels. The experiment was conducted at the Shiyanghe Experimental Station for Water-Saving in Agriculture and Ecology of China Agricultural University in Wuwei, Gansu, over a period of two years. Three irrigation levels were applied: A₁ (100% measured evapotranspiration (ETc)), A₂ (66% of A₁), A₃ (33% of A₁) and A₄ (a rain-fed treatment). The results showed that plant height (H) and stem-leaf ratio (SLR) increased while the fresh-dry ratio (FDR) decreased with plant maturity. All these growth characteristics decreased with lowering levels of irrigation. In terms of quality, crude protein (CP) decreased but neutral detergent fiber (NDF) and acid detergent fiber (ADF) increased with plant maturity. NDF and ADF decreased and CP increased with lowering levels of irrigation. H and SLR had a significant linear relationship with quality (P<0.001). The coefficients of determination between quality and H (R²>0.900) were higher than those for SLR, while the results for FDR were not significant. These results imply that, when field management is good, alfalfa height could be used to estimate forage quality.