共查询到17条相似文献，搜索用时 187 毫秒
1.
2.
3.
种植密度对不同耐密夏玉米品种茎秆性状与抗倒伏能力的影响 总被引：8，自引：0，他引：8
以耐密性不同玉米品种为材料,调查吐丝期暴雨大风后玉米倒伏情况,分析增密过程中不同夏玉米群体植株形态与茎秆力学变化规律。结果表明,随密度增加,大风后根倒率和茎折率显著增加,登海618的根倒率和茎折率显著低于浚单20。随着密度增加,玉米株高和穗位高增加,基部3~7节间均表现为节间伸长、变细,茎粗系数、穿刺强度、抗折力、压碎强度显著降低,两个品种表现一致。相关分析表明,根倒率和茎折率与节间长度、株高、穗位高和穗位系数正相关,与茎粗、茎粗系数和茎秆力学负相关。站秆率与倒伏率均与基部第3节间性状的相关性达显著水平。与浚单20相比,登海618具有较低的节间长度、株高、穗位高、穗位系数和较高的茎粗、茎粗系数和茎秆力学,抗倒性能较强。 相似文献
4.
5.
6.
以黄旦、福鼎大白茶、肉桂、毛蟹、铁观音鲜叶为原料,对其驻芽一、二、三叶进行力学特性及粗纤维含量的测定,研究表明,茶树嫩梢的弹性模量在4 158.88~14 849.11 kPa,最大应力在870.00~1 842.97 kPa,断裂应力在673.33~1 639.62 kPa,叶位对弹性模量、最大应力与断裂应力的影响达到极显著水平,大小排序为:三叶>二叶>一叶。茶树嫩梢最大力点应变在10.61%~18.36%,断裂应变在12.19%~26.95%,叶位对最大应力与断裂应力的影响达到极显著水平,大小排序为:三叶>二叶>一叶,不同品种有所差异。茶树嫩梢力学参数为茶叶加工机械设计提供了一定的参考价值。 相似文献
7.
以仲玉3号和正红6号玉米为试材,设置6.75×104、8.25×104株/hm2两个种植密度,研究密植条件下夏玉米子粒、穗轴脱水及力学特性的变化规律,探明二者之间的关系。结果表明,随着种植密度的增加,穗部器官脱水减慢、含水率增加,力学强度呈下降趋势。品种间穗部脱水及力学强度存在显著差异,且远大于种植密度及二者交互作用的影响。与正红6号(ZH6)相比,仲玉3号(ZY3)脱水较快,到达适宜机械粒收含水率时所需吐丝后积温较少,收获时ZY3子粒压碎强度与穿刺强度大,穗轴抗折断力小,茎秆倒伏率低,机收性能更好。相关性分析显示,子粒与穗轴力学强度与含水率均呈显著负相关;穗轴抗折断力与干重、单位长度干重及单位体积干重呈极显著正相关,与穗轴长、长粗比呈极显著负相关。密度与品种对子粒产量存在无显著差异,随着种植密度的提高,茎秆倒伏率显著增大,ZY3生理成熟后脱水速率显著降低,达到宜机收子粒含水率所需积温增多。 相似文献
8.
茶树嫩梢力学特性与粗纤维试验 总被引：1，自引：0，他引：1
以黄旦、福鼎大白茶、肉桂、毛蟹、铁观音鲜叶为原料,对其驻芽一、二、三叶进行力学特性及粗纤维含量的测定,研究表明,茶树嫩梢的弹性模量在4 158.88～14 849.11 kPa,最大应力在870.00～1 842.97 kPa,断裂应力在673.33～1 639.62 kPa,叶位对弹性模量、最大应力与断裂应力的影响达到极显著水平,大小排序为:三叶＞二叶＞一叶.茶树嫩梢最大力点应变在10.61％～18.36％,断裂应变在12.19％～26.95％,叶位对最大应力与断裂应力的影响达到极显著水平,大小排序为:三叶＞二叶＞一叶,不同品种有所差异.茶树嫩梢力学参数为茶叶加工机械设计提供了一定的参考价值. 相似文献
9.
10.
为从力学角度分析栽培年份、种植密度及主要化学成分指标对大豆种质资源抗倒伏性的影响,为基于主茎力学特性进行大豆抗倒伏的资源鉴定和新品种选育提供理论依据,本研究于2020和2021年在田间种植190份大豆资源,在成熟期测量株高、直径、折断力3种主茎表型性状及木质素、纤维素含量两种化学成份指标,对不同种植年份不同大豆资源的主茎表型性状进行方差分析,对各大豆资源3种主茎表型性状进行相关性分析。同时,在2020年筛选抗倒伏特性差异明显的20份大豆材料,于2021年进行盆栽种植,设置两个种植密度处理(20万和30万株·hm-2),在成熟期测定主茎表型性状和化学成份指标,并计算弹性模量和抗倒伏系数,分析种植密度及主茎力学相关指标与大豆抗倒伏性的关系。结果表明：年份与折断力互作、品种(系)与折断力互作显著。年际间环境条件差异对折断力有较大影响,折断力大的品种(系)抗倒伏系数也高。主茎折断力与直径呈正相关,而直径与株高之间无明显规律。大豆抗倒伏系数与折断力、弹性模量呈极显著正相关,相关系数分别为0.90和0.42。两个种植密度下折断力较大的品种(系)植株抗倒伏系数和弹性模量均大于折... 相似文献
11.
剪切特性指标可以用来评价茶叶的嫩度,本文通过剪切试验获得了茶叶剪切特性的力学指标(硬度、破坏能、破坏力及破坏应力等),同时针对茶叶梗直径尺寸较小,运用图像分析的方法,获得茶叶梗外形尺寸及其他参数,综合分析建立了不同品种茶叶嫩度和剪切力学指标之间的数学模型,为客观评价茶叶的等级提供新的手段和研究方法。 相似文献
12.
Many industrial products are made of cord-rubber composite materials. Their mechanical behavior not only depends on rubber but also depends on cord. Nylon 66 cord is one of the most important reinforcement in these products. This paper research the mechanical behavior of nylon 66 cord under various load cases. A series of experiments were carried out to obtaining stress-strain curves under different load cases. Complex changes of the modulus and Mullins effect can be found in monotonic and cyclic tension, respectively. Mechanism of these behaviors has been analyzed considering both the twisted structure and material. A phenomenological constitutive model, accounting for different loading conditions, has been firstly proposed base on strain energy density function and damage mechanics method. The proposed model has been verified by comparing the predicted results with experimental data. It has been found that the proposed model predicted the stress-strain curves that were consistent with the experimental data. The proposed model can be implemented in finite element software for engineering design and application. 相似文献
13.
甘蔗在中国糖料生产中占重要地位，甘蔗叶是一种储量巨大且亟待开发利用的生物质能源，具有很好的开发利用价值。然而，目前对甘蔗叶生物力学特性方面的研究尚缺乏有效的研究理论与方法。本研究引入新兴的农业生物力学研究理论，结合工程学、生物学、工程力学和工程材料学的基本原理与方法，研究甘蔗叶拉伸力学性能、甘蔗叶剪切力学性能、甘蔗叶力学性能，为研究甘蔗叶的生物力学特性寻找到有效的研究理论与方法，为甘蔗叶粉碎还田、甘蔗叶沼气利用预处理机械，以及甘蔗剥叶、收获等机械的研究开发、优化设计、计算机仿真及智能化提供参考。 相似文献
14.
B. J. Dobraszczyk M. B. Whitworth J. F. V. Vincent A. A. Khan 《Journal of Cereal Science》2002,35(3):245
The fracture properties of small, cylindrical samples of endosperm machined from single kernels of several varieties of wheat were measured using three methods: compression, wedge fracture and indentation. In addition, dynamic compression tests were also performed in impact loading. Density measurements using a variable density liquid gradient were carried out on machined endosperm samples that had previously been tested for fracture properties, enabling direct comparisons between their density and fracture properties. Within each variety, a distribution of density and hardness values was found. Soft wheat varieties (Riband, Apollo) showed a broad distribution of density with medians in the range 1340 to 1395 kg/m3, whilst hard varieties such as Mercia and a durum wheat exhibited much narrower distributions and higher mean densities, Mercia being skewed towards higher densities, with a median at around 1410 kg/m3. A considerable amount of overlap in density between the soft and hard variety occurred, with both containing a significant proportion of harder and higher density wheat grains, and the major difference appearing to be the presence in the soft wheat of a large proportion of lower density endosperm in the range 1280 to 1360 kg/m3. The differences in density between endosperm samples were attributed to variations in endosperm porosity, which were correlated with the fracture properties of the endosperm. It is proposed that increased levels of porosity weaken the endosperm structure and are responsible in part for soft endosperm texture. The relationship between endosperm density and fracture properties was non-linear, the failure stress and fracture toughness increasing rapidly as the density approached a limiting value corresponding to the density expected for pore-free endosperm. This indicates that endosperm is a notch sensitive material, where the pores concentrate applied stresses and can act as sites of crack initiation. It was shown that the notch sensitivity of endosperm is qualitatively consistent with models of brittle fracture based on fracture mechanics theory, i.e. stress concentration by voids. 相似文献
15.
呼吸作用是果蔬产品采后最为基本的生理过程,降低采后呼吸作用,维持果蔬产品正常而缓慢的生命活动,是果蔬采后生理及贮藏技术研究的中心问题.该文从呼吸作用入手,阐述了呼吸的基本概念,影响果蔬呼吸作用的因素及生理意义,可为呼吸作用的课堂教学提供参考. 相似文献
16.
17.
针对园林模型制作课程教学中存在的问题,提出教学改革措施,并进一步阐述园林模型制作课程与园林专业基础课结合,相互渗透的意义。 相似文献