Broad bean fits sustainable agriculture model due to symbiosis with Rhizobium, the seeds being a good source of energy, proteins, polyphenols, and fiber. The large amount of broad bean biomass residues can be employed for biofuel production, thus valorizing the overall production process. This research was aimed to investigate on the effects of farming management, such as greenhouse cultivation and appropriate planting time on the qualities of broad bean seeds and residual biomass for conversion into biofuel. The related balances of energy gain associated to both ethanol yield and nitrogen fertilizer saving due to Rhizobium nitrogen fixation were assessed. Research was carried out on broad bean in Portici, province of Naples, southern Italy, based on the factorial combination of two farming systems (open field, greenhouse) and five planting times: 27 September and 11 October, to obtain early production; 25 October, which fell in the usual period for broad bean planting in the province area; and 8 November and 22 November, for late production. For each of these cultivation conditions, the quality of seeds, in terms of protein, fiber and antioxidant concentrations, and of crop residual biomass were determined. In addition, the energy yield as ethanol production from residual biomass and nitrogen fertilizer saving due to Rhizobium atmospheric fixation were assessed. The highest plant nitrogen uptake was recorded under the fourth planting time in open field and the third in greenhouse, the average accumulation attaining 87% in residual biomass, 7.4% in pods, and 5.6% in seeds. Seed protein content was 12.6% higher in greenhouse than in open field and 16.2% higher under the latest planting time compared to the earliest one. Seed polyphenol concentration was higher in open field than in greenhouse and with the two earliest planting times. Greenhouse grown biomass showed higher values of lignin, hemicellulose and pectin, compared to open field, whereas the opposite trend was for cellulose. Lignin showed a decrease from the first to the last crop cycle, opposite to cellulose, and glucose was the most represented monosaccharide. Both the highest theoretical ethanol and overall energy production were highest with the fourth planting time. Greenhouse management enabled broad bean plants to accumulate higher proteins in seeds, but open field conditions resulted in better residual biomass quality for ethanol and Rhizobium-depending energy production.

中文翻译：

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植物–根瘤菌共生，种子营养品以及受作物管理影响的蚕豆能源生产的废物质量

蚕豆与根瘤菌共生，因此符合可持续农业模式，种子是能量，蛋白质，多酚和纤维的良好来源。大量蚕豆生物质残留物可用于生物燃料生产，从而使整个生产过程价值不菲。这项研究旨在研究诸如温室栽培和适当的播种时间等耕作管理对蚕豆种子品质和转化为生物燃料的残留生物质的影响。评估了由于根瘤菌固氮而与乙醇产量和氮肥节省相关的能量获取的相关平衡。基于两种耕作系统（露天，温室）和五种种植时间的因子组合，对意大利南部那不勒斯省Portici的蚕豆进行了研究：9月27日和10月11日，以获得早期生产；10月25日，在该省地区的蚕豆种植通常时期有所下降；以及11月8日和11月22日，用于后期生产。对于每种这些栽培条件，都根据蛋白质，纤维和抗氧化剂的浓度以及作物残留生物量确定了种子的质量。此外，还评估了由于残留生物量产生的乙醇产生的能源产量以及由于根瘤菌大气固定而节省的氮肥。在空地第四次种植和温室第三次种植下记录到最高的植物氮吸收量，平均积累量分别为残留生物量87％，豆荚7.4％和种子5.6％。大棚中的种子蛋白质含量比露天大16.6％，高16种。与最早的播种时间相比，最新的播种时间高出2％。两次播种时间最早，露天土壤中的种子多酚浓度高于温室。与开阔地相比，温室种植的生物量显示出更高的木质素，半纤维素和果胶价值，而相反的趋势是纤维素。木质素从第一个到最后一个农作周期显示出减少的趋势，与纤维素相反，而葡萄糖是最具代表性的单糖。第四种植时间，最高的理论乙醇和总的能量产量最高。温室管理使蚕豆植物能够在种子中积累更高的蛋白质，但是开阔的田间条件导致乙醇和根瘤菌相关能源生产的残留生物质更好。