绿萍全年高产配套技术研究

优良萍种是绿萍高产的基础。选用耐寒、抗热萍种周年养殖，比常规萍种生长期延长80-110天，每亩绿萍的年产量可提高1.08-1.22万公斤。优良萍种交替应用、配套养殖，能发挥多萍种的群体优势，克服气候条件的制约，使绿萍年产量达到每亩3.91万公斤。改进施肥技术，合理施用肥料是充分发挥绿萍生产潜力的重要措施。盆栽和田间小区试验，用鸡粪液代替以过磷酸钙为主的施肥技术，萍产量可提高23.3%-62.0%；含氮量提高44.8%。配施钾肥有利于改善萍体素质，提高繁殖速度，增加绿萍产量，不同萍种的增产幅度达29.4%-85.4%。实行科学管理,是保持绿萍群体生长优势，提高适应能力的必要条件。调节萍群结构、协调留种数量和繁殖速度的矛盾，增强萍种的耐寒、抗热能力及防治虫害等一整套技术措施，在全年生产中要综合应用，才能达到高产目的。

A STUDY OF COMPREHENSIVE TECHNIQUE IN THE HIGH ANNUAL YIELD OF AZOLLA

Fine Azolla species are the basis of high yield. Selecting cold and heat-resistant species and cultivating them all year round can prolong the growth period by 80-110days and increase the annual yield by 10.8-12.2t/mu(fresh wt)as compared with the conventional spacies. Forming a complete set of fine Azollf~ species for alternative cultivation can bring into full play the superiority of various species and surmount limitations of the climatic conditions so that the annual yield can come to 39.1t/too (fresh wt). Improvement and rationalization in fertilization arc important measures for giving full play to all potentialities of Azolla production. Applying liquid of chicken excreta in place of the dominative application of calcium superphosphate in our experiments in open air pots and plots proved that the yield and the nitrogen content raised 23.3~-62.0~ and 44.8~ respectively. Additional application of potash fertilizer led to improving Azolla quality, accelerating the multiplication rate and increasing its output. The increase in yield for different Azolla species ranged from 29.4~-85.4~. Scientific management is the prerequisite for keeping the growth superiority of Azoila mats and raising their adaptability. High yield cannot be expected in a year-round cultivation of Azolla unless a whole set of techniques-adjusting the structure of AzoUa mats, reconciling the contradictions between the quantity preserved for regrowth and the multiplication rate, enhancing its culd-and heat-resistant ability, controling insect pests and so on-are comprehensively used.