如何提高梭子蟹育苗中大眼幼体的成活率

1严格挑选抢卵蟹1.1排幼亲蟹的选择。挂笼的抱卵梭子蟹需要严格挑选,胚胎颜色为灰白色。呈红黄色的胚胎为死胚胎,应舍弃。附肢残缺太多的抱卵蟹易流产,不可选用。1.2亲蟹消毒。排幼的亲蟹用20毫克/公斤孔雀石绿溶液和20毫克/公斤甲醛溶液浸泡1小时,最后放入消毒海水浸泡30分钟,     

Comparison and early selection of new clones in Populus tomentosa

In our study, two experimental plantations, respectively, with 24 and 32 new clones of P. tomentosa, were established in Weixian County, Hebei Province and Wuzhi County, Henan Province using a completely randomized block design. A comparative study was conducted on the continuous 5-year-old height and diameter at breast height (DBH) of new clones in the two plantations. As well, based on genetic correlation over the years of testing of these clones, a preliminary study of early selection was carried out. Results indicate that the growth traits of the new clones in Weixian were better than those in Wuzhi The traits show weak correlation between the two plantations. In some stands, the height, DBH and seedling volume of 5-year-old clones presented statistically sig-nificant differences among clones. In both plantations, the new clones showed over 0.6 repeatability of beight, DBH and volume, as well as larger coefficients of variation (CV). The fact that these clones achieved the largest repeatability and CV in the second year suggests that these traits are highly controlled by heredity. Thus, based on the growth traits of the second year, the new clones B305, B307, B303, H75, BT18, BTI7 and 21J-1 were considered suitable in Weixian. hi Wuzhi, the new clones had variable repeatability and CVs in various years and their correlation of growth traits among different years was not high. We conclude that early selection of new clones was not feasible in Wuzhi.     

冬季养鹅把“十关”

1．选好苗鹅 要挑选“老鹅婆”孵化的体型一致、体壮头大、眼睛灵活、绒毛整齐、色泽金黄、活泼健壮、善于觅食、挣扎有力、脚粗蹊阔、腹部无硬结的雏鹅来喂养。     

金丝小枣栽培与管理(续5)

15．1整理晾晒场地。挑选向阳、平坦、地势高的场地。根据采收前雨量多少、湿度大小确定搪箔高度。湿度大的年份，搪箔时先平放一砖、上面再放一陡砖，砖上搪上竹片或秫秸把，铺上箔即可。湿度中等年份高度可用一陡砖，特干年份把砖平放搪箔便行。     

怎样挑选高产奶牛

根据奶牛品种 当前全世界奶牛品种，主要有荷斯坦牛(黑白花牛)、娟珊牛、更赛牛、爱尔夏牛及瑞士褐牛。我国饲养奶牛品种中95％以上是中国荷斯坦牛(中国黑白花牛)，此外还有新疆褐牛、三河牛及草原红牛等。荷斯坦牛属大体型奶牛，产奶量最高。所以为了获得奶牛高产，首先应选择荷斯坦牛。在饲养条件较差的地区，也可选择其他品种。     

食用土元的养殖技术及开发前景

土元又名地鳖虫.通过蜕皮生长,平均每15天蜕皮1次,一生蜕皮9～11次,每次蜕皮前后24小时不食不动,变成空腹,外表白色,皮嫩而干净的白土元,12小时之内不变色,食用起来味美,口感好,称为食用土元.     

怎样挑选新手扶拖拉机

首先，要从外观上检查一下机车的各主要部件是否齐全，离合器杆、变速杆等是否有变形，特别要仔细检查各部的紧固螺丝和开口销子是否有松动、脱落现象。加注燃油、机油、冷却水后，将变速杆放在空挡位置上。搬动减压装置，摇转曲轴，让发动机着火。此时要立刻观察发动机后端红色的机油压力指示阀是否升起，如果升起，表示汕压正常。注意倾听发动机有无杂音。     

虾米脱壳机

我省宝安市盐田水产站于1975年试制成功虾米联合脱壳机，基本上实现了送料、剥壳、分离挑选的机械化。     

怎样决定截桩的高度

盆景的桩材大多为野生桩, 如果要在众多的树桩中挑选出符合盆景造型的桩材,就得掌握一定的选桩知识:1．必须是适合盆景造型的树种。2．桩材要有好的根、头,特圳要有中小根、须根。 3．干身要有一定的曲度(直干式除外),过渡要自然,顶干要逐级