Growth promotion of Guinea grass by diazotrophic bacteria1

ABSTRACT The Panicum maximum species (cv. Mombaça) is a forage plant well adapted to the different edaphoclimatic conditions found in Brazil; however, it requires high nitrogen fertilizer doses to ensure high yields. The present study aimed to assess the inoculation effect with associative diazotrophic bacteria strains on the yield and bromatological characteristics of the Guinea grass. A randomized block design was used, consisting of 25 treatments, being 23 of them inoculated with diazotrophic bacteria and two without inoculation (one with and the other without mineral nitrogen), with four repetitions. The analyzed variables were stem diameter; leaf width and length; leaf, stem and root dry mass yield; crude protein; acid and neutral detergent fibers. There were no differences among the treatments for root dry mass, stem diameter and acid detergent fiber. For the remaining variables, a positive effect of the inoculation with diazotrophic bacteria was observed, particularly for the following Unifenas strains: 100-06, 100-13, 100-26, 100-30, 10-35, 100-54, 100-69, 100-71 and 100-94. This reveals the potential of these bacterial strains for use at the sustainable production of the Guinea grass with a reduction in the use of nitrogen inputs.

摘要：大黍（Panicum maximum）品种Mombaça是一种适配巴西多样土壤气候条件的优质饲用植物，但需施加高剂量矿质氮肥方可实现高产。本研究旨在评估联合固氮细菌（associative diazotrophic bacteria）菌株接种对几内亚草（即大黍）产量与营养品质特性的影响。实验采用随机区组设计，共设置25个处理组：其中23组接种固氮细菌，剩余2组不接种（分别为施加矿质氮肥对照组与无氮肥对照组），每组设置4次生物学重复。测定指标涵盖茎直径、叶长与叶宽、叶、茎及根干物质产量、粗蛋白含量、酸性洗涤纤维及中性洗涤纤维含量。结果表明，根干物质产量、茎直径及酸性洗涤纤维在各处理组间无显著差异；其余指标均体现出接种固氮细菌的正向调控效果，其中尤以Unifenas菌株库内的100-06、100-13、100-26、100-30、10-35、100-54、100-69、100-71及100-94菌株效果突出。本研究证实，上述细菌菌株具备应用于几内亚草可持续生产的潜力，可有效降低氮肥投入量。