006第五章 豆科牧草(苜蓿-3)2 饲草生产学教学课件.pptVIP

???????????????????????????????????????????????????????????????????? Faster recovery and regrowth after each cutting results in a crop ready for harvest 3-5 days earlier and compounds during the season to maximize total yield.  北方地区春播当年，若有灌溉条件，可刈割1～2次，此后每年可刈割3～5次，长江流域每年可刈割5～7次。鲜草产量一般为15～60t/hm2，水肥条件好时可达75t/hm2以上。 （五）收获利用 各次刈割的产量以第一茬最高，约占总产量的50%左右，第二茬约为总产量的20%～25%，第三茬和第四茬为10%～15%。 （五）收获利用 放牧 （五）收获利用 此外，苜蓿对磷、钾的反应与土壤的性质有关，如施用同量的磷，在黏壤土上产量增幅高于沙壤土。 在返青及刈割后和越冬前要注意追施磷、钾肥，以提高其产量和品质，并利于越冬。 田间管理 灌溉是提高苜蓿产草量的重要措施，因此在有灌溉条件的地方，应适时适量灌溉，以促进生长，增加产量。但随着灌水量的增加，苜蓿品质有下降趋势。苜蓿又忌积水，降雨后造成积水时应及时排除，以防烂根死亡。 灌溉 田间管理 冬灌 春灌 再生草灌溉 排渠 Both surface and subsurface drainage are essential to alfalfa winter survival. Heaving occurs on heavy soils 粘重土壤with poor drainage since repeated freezing and thawing cause the taproot 主根to be pushed out of the soil. Plants heaving more than 1 in. will dry out and have broken taproots and lateral roots侧根, and elevated crowns根颈. These plants will die or be severely stunted. Surface drainage is a bigger issue on flat land than on rolling land, because with frozen ground, the water cannot drain off the field, resulting in ice sheeting. 冻拔 Alfalfa heaving is caused by freeze/thaw cycles of early spring, lifting the crown up 苜蓿常见病害有菌核病、霜霉病、锈病、褐斑病、白粉病等，发现病害后应及时拔除病株，或提前刈割，或用石灰硫磺合剂、福美双、甲基托布津、波尔多液、粉锈宁、多菌灵等药物进行防治。 病虫害防治 田间管理 Early stages of infection with verticillium wilt. Notice the leaf on the left side of the stem with characteristic V-shaped chlorosis. Most often leaves will initially be chlorotic and eventually take on a pinkish hue颜色, followed by abscission脱落. Alfalfa stems with a range of severity. Mild infection on the left to severe on the right. 黄萎病，Verticillium Wilt of Alfalfa 颈腐病 Crown Rot of Alfalfa Crown rot results in a dry rot of the crown and root cortex 皮层leading to stunted plants with low vigor and eventual death. Notice the brown rotted root cortex characteristic of Crown Rot. 黑颈病 Spring Black Stem of Alfalfa Alfalfa stem