Regulations On Vegetative And Reproductive Growth Of Alfalfa (Medicago Sativa L.)

Alfalfa(Medicago sativa L.)seed production have higher request to climate condition and cultivation techniques. In this paper, in order to increase seed yield, the influence of row spacing, irrigation rate, fertilizer rate (includes N, P, K and micronutrients), plant growth regulator (PGR) and drying agent on vegetative and reproductive growth of Gannong No.3 alfalfa were researched, meantime, growth redundancy of alfalfa population were also researched. By two years'study, following conclusions were reached:1. Growing stage and seed yield of Gannong No.3 alfalfa were different between the planting year and the second year. (1) Compared with planting year, growing period of alfalfa at the second year shorten about 50～53 days. At the same year, along with increasing of row spacing, growth stage advanced and plant height reduced. Growing stage and plant height were similar among different irrigation and fertilizer rate. (2) When row spacing was small, plant covered the earth, evaporation among plants was smaller and soil moisture content was higher. Along with increasing of row spacing, evaporation among plants increased and soil moisture reduced quickly. Under the same row spacing, along with the increasing of irrigation rate, soil moisture was increased gradually. (3) At the planting year and second year, the highest actual seed yield (501.9kg/hm2, 1503.26kg/hm2) were obtained with 100cm of row spacing and 900 m3/hm2 of irrigation rate. (4) Row spacing and irrigation rate had different effect on seed yield components of alfalfa. Row spacing had significant influence on effect shoots/m2, florets/shoot, pods/floret and seeds/pod. Irrigation rate had insignificant influence on seed yield components. Among seed yield components, pods/floret and seeds/pod positively correlated with desirable seed yield at 0.01 level, correlation coefficients were 0.883** and 0.877** respectively. Florets/shoot positively correlated with actual seed at 0.05 level, R2=0.746*.2. N, P and K fertilizer had different effect on vegetative and reproductive growth of alfalfa. (1)When fertilizer rate was 47 kg N/hm2, 120 kg P2O5/hm2 and 30 kg K2O /hm2, alfalfa population was in best condition and highest actual seed yield (1356.42 kg /hm2) was obtained. (2) Among seed yield components, seeds/pod and pods/floret positively correlated with desirable seed yield at 0.01 level, correlation coefficients were 0.899** and 0.868** respectively.3. Three plant growth regulators (PP333, CCC, EP) had different effect on vegetative and reproductive growth of alfalfa. (1) All could retard vegetative growth and accelerate reproductive growth, made the period from emergence (greening) to flowering longer, flowering to maturing...