几种引进牧草种子质量检验分析

根据标准牧草检验规程对紫花苜蓿、白三叶、多年生黑麦草、无芒雀麦、草地羊茅、鸭茅等进行种子净度、种子发芽率、种子生活力、种子水分含量、电导率5项指标的测定。结果表明紫花苜蓿、白三叶、草地羊茅发芽率指数相对高,无芒雀麦、黑麦草、鸭茅发芽指数低;紫花苜蓿、白三叶、多年生黑麦草的生活力高,而无芒雀麦、鸭茅、草地羊茅的生活力较低,对田间种植有一定的指导意义。

Effect of Water Stress Caused by PEG 6000 on Germination and Seedling Growth of Four Soybean Cultivars

Soybean [Glycine max （L.）] is one of the most important protein and oil seed crop. In attention to time consuming and effect of uncontrolled agents like soil elements and hemisphere, study of tolerance in soybean to water stress during germination was investigated. Four soybean cultivars ＇Williams, Linford, L 17 and M7＇ were screened for drought tolerance by treatment of PEG6000 concentration for induce osmotic potentials （0, -3, -6, -9 bar）. A factorial experiment based on completely randomized design with three replications was conducted. Germination percentage, radicle and hypocotyls length, fresh and dry weight of radicle, hypocotyl and seedling, TWC%, MDG, rate of daily germination and percentage of abnormal seedling were measured. Variance analysis of data indicated that difference between osmotic potential had significant effect on all parameters except germination percentage. A significant reduction in fresh weight of radicle and seedling, percentage of abnormal seedlings was observed for the genotypes as the concentration of PEG increased. In interaction between cultivars and water stress level, Linford and M7 with less damage had the highest yield in fresh and dry weight of radicle, respectively. Drought is one of the most important abiotic limited potential in germination and primary growth on these cultivars.

Frictional Behavior of Sunflower Seed and its Kernel as a Function of Moisture Content, Variety and Size

The object of this study was to investigate the frictional properties （repose angles and friction coefficient） of Iranian sunflower seed and its kernel （Fandoghi, Azargol and Shahroodi） as a function of moisture content, size and variety. The static coefficient of friction were determined on five structural surfaces including aluminium, plywood, galvanized iron, polyethylene and rubber when moisture content varied between 3 and 14 % d.b. The obtained results showed that static coefficient of friction on five studied surfaces increase linearly as moisture content increase from 3 to 14% for both seed and kernel. Among the applied surfaces, rubber showed the highest value of friction coefficient for both sunflower seed and kernel followed by plywood, polyethylene, galvanized iron and aluminium. The obtained values of emptying and filling angles of repose increase linearly with an increase in moisture content. Furthermore, the values of empting and filling angles of repose for small sizes were higher than big sizes in all levels of moisture content for both seed and kernel. Also, the emptying angle of repose assumed higher values than the filling angle of repose for all varieties and categories.

Mechanical Properties of Sunflower Seed and Its Kernel, Azargol Variety as a Case Study, under Compressive Loading

The objective of this study was to investigate the effect of moisture content, size and loading orientation on mechanical properties such as force, deformation and energy absorbed per unit volume for fracturing Iranian sunflower seed and its kernel （Azargol as a case study） under quasi-static loading. Sunflower seeds and their kernels were quasi-statically loaded in horizontal and vertical orientations with moisture content in three levels： 3%, 7% and 14%, and size category in three levels： small, medium and large. The obtained results showed that rupture force for both sunflower seed and its kernel decreased with increasing moisture content while the absorbed energy and deformation at rupture point increased for all size categories in both horizontal and vertical loading orientations. Also, seeds in the vertical orientation developed hull cracks at a higher level of force than those loaded in the horizontal orientation. However, for the kernels it was the opposite. In addition, the average forces required to cause kernel rupture were lower （11.64-39.9 N） than those required to rupture the seed （30.06-117.46 N） in both orientations. Seeds loaded in a vertical orientation absorbed more energy （87.67 mJ） prior to rupture than those loaded in the horizontal （46.60 mJ） orientation. However, for the kernels it was the opposite.

不同脱水剂对杂交水稻种子成熟期脱水效果和质量的影响

在Ⅱ优1681制种田比较了28种脱水剂在种子成熟后期的脱水效果及对种子质量的影响,结果表明,复合型脱水剂F-2-5、F-4-5和F-5-5的脱水效果好,种子水分含量比对照降低5个百分点以上,且对种子千粒重、发芽率和活力影响小。进一步在Y两优143和两优培九制种田研究了脱水剂的不同施用量对种子水分含量、千粒重和质量的影响,结果表明,喷施2~3L/hm^2复合型脱水剂F-4-5和F-5-5后,种子水分含量显著低于对照,比对照降低4个百分点以上;其中,喷施2~3 L/hm^2复合型脱水剂F-5-5后,种子千粒重、发芽率和活力也不低于对照。综合来看,F-5-5是一种脱水效果较好且对种子质量影响较小的脱水剂,其适宜的施用量为2~3 L/hm^2。