Morris Geoffrey P, Hu Zhenbin, Grabowski Paul P, Borevitz Justin O, de Graaff Marie-Anne, Miller R Michael, Jastrow Julie D
Department of Agronomy Kansas State University Manhattan KS 66506 USA.
USDA-ARS Dairy Forage Research Center Madison WI 53706 USA.
Glob Change Biol Bioenergy. 2016 Sep;8(5):1000-1014. doi: 10.1111/gcbb.12309. Epub 2016 Jan 10.
The perennial grass species that are being developed as biomass feedstock crops harbor extensive genotypic diversity, but the effects of this diversity on biomass production are not well understood. We investigated the effects of genotypic diversity in switchgrass () and big bluestem () on perennial biomass cropping systems in two experiments conducted over 2008-2014 at a 5.4-ha fertile field site in northeastern Illinois, USA. We varied levels of switchgrass and big bluestem genotypic diversity using various local and nonlocal cultivars - under low or high species diversity, with or without nitrogen inputs - and quantified establishment, biomass yield, and biomass composition. In one experiment ('agronomic trial'), we compared three switchgrass cultivars in monoculture to a switchgrass cultivar mixture and three different species mixtures, with or without N fertilization. In another experiment ('diversity gradient'), we varied diversity levels in switchgrass and big bluestem (1, 2, 4, or 6 cultivars per plot), with one or two species per plot. In both experiments, cultivar mixtures produced yields equivalent to or greater than the best cultivars. In the agronomic trial, the three switchgrass mixture showed the highest production overall, though not significantly different than best cultivar monoculture. In the diversity gradient, genotypic mixtures had one-third higher biomass production than the average monoculture, and none of the monocultures were significantly higher yielding than the average mixture. Year-to-year variation in yields was lowest in the three-cultivar switchgrass mixtures and Cave-In-Rock (the southern Illinois cultivar) and also reduced in the mixture of switchgrass and big bluestem relative to the species monocultures. The effects of genotypic diversity on biomass composition were modest relative to the differences among species and genotypes. Our findings suggest that local genotypes can be included in biomass cropping systems without compromising yields and that genotypic mixtures could help provide high, stable yields of high-quality biomass feedstocks.
正在被开发用作生物质原料作物的多年生草本物种具有广泛的基因型多样性，但这种多样性对生物质产量的影响尚未得到充分了解。我们于2008年至2014年在美国伊利诺伊州东北部一块5.4公顷的肥沃农田上进行了两项实验，研究柳枝稷（）和大须芒草（）的基因型多样性对多年生生物质种植系统的影响。我们使用各种本地和非本地品种，在低或高物种多样性、有或无氮输入的条件下，改变柳枝稷和大须芒草的基因型多样性水平，并对植株建立、生物量产量和生物量组成进行了量化。在一项实验（“农艺试验”）中，我们将三种柳枝稷品种的单作与一种柳枝稷品种混合物以及三种不同的物种混合物进行了比较，有无施氮肥。在另一项实验（“多样性梯度试验”）中，我们改变了柳枝稷和大须芒草的多样性水平（每块地1、2、4或6个品种），每块地有一个或两个物种。在两项实验中，品种混合物的产量都等于或高于最佳品种。在农艺试验中，三种柳枝稷混合物总体产量最高，尽管与最佳品种单作没有显著差异。在多样性梯度试验中，基因型混合物的生物量产量比平均单作高1/3，且没有一种单作的产量显著高于平均混合物。在三种柳枝稷品种混合物以及Cave-In-Rock（伊利诺伊州南部品种）中，产量的年际变化最小，相对于物种单作，柳枝稷和大须芒草的混合物中的产量年际变化也有所减少。相对于物种和基因型之间的差异，基因型多样性对生物量组成的影响较小。我们的研究结果表明，本地基因型可以纳入生物质种植系统而不影响产量，并且基因型混合物有助于提供高质量生物质原料的高且稳定的产量。
