不同产地苦楝苗期生长节律研究

Annual growth rhythm of Melia azedarach seedlings from different seed sources

苦楝在我国分布广泛,具有丰富的遗传变异性。为进一步做好苦楝种源筛选和良种选育工作,该文对不同产地苦楝实生苗生长性状和各阶段的生长特点进行了比较分析,初步揭示了苦楝苗期生长规律。以15个产地的1年生实生苗为试材,对苗高、地径、复叶生长及生物量积累等生长性状进行了观测分析,并用Logistics方程对生长节律进行了拟合。结果表明:(1)不同产地苦楝苗高、地径生长差异均达显著水平,根生物量、茎生物量及复叶相关性状差异均达极显著性水平;(2)苗高和地径生长均呈现慢-快-慢的S型生长规律,且均存在2次生长高峰,与苗高生长高峰出现时间相比,地径生长高峰出现时间较晚;(3)Logistic拟合方程的R^(2)为0.976~0.994,均达到极显著相关水平,说明可用Logistic方程拟合苦楝的生长节律;(4)总体上地径速生期较苗高速生期长20~30 d,北方产地苗高和地径进入速生期和结束速生期的时间均早于南方产地,速生期苗高和地径累积生长量均超过总生长量的60%;(5)各生长指标均与纬度负相关,苗高、生物量及复叶面积与经度正相关,其他指标与经度负相关。综上结果表明,苦楝为全期生长型树种,各生长性状在产地间达显著差异水平,生长受纬度和经度双重控制,以纬度控制为主。

Melia azedarach is widely distributed in China and has a wide range of genetic variation.In order to study the growth characters of one-year-old seedlings of M.azedarach from different seed sources,the growth characters of seedling height,ground diameter,compound leaf growth and biomass accumulation of M.azedarach seedlings from 15 seed sources were observed,and the growth rhythm was fitted by logistic equation.The results were as follows:(1)There were significant differences between seedling height and ground diameter(P<0.05),and significant differences between root biomass,stem biomass and compound leaf(P<0.01).(2)The growth of seedling height and ground diameter showed a slow-fast-slow growth pattern with type S.Compared with the emergence time of seedling height growth peak,the emergence time of ground diameter growth peak was later.(3)The R 2 of logistic fitting equation was 0.976-0.994,which reached the extremely significant correlation level,indicating that the growth rhythm of M.azedarach can be fitted by logistic equation.(4)According to theoretical calculation and practical observation,the duration of fast-growing stage of ground diameter was generally 20-30 d longer than that of high-speed growth stage of seedling.The time of seedling height and ground diameter entering fast-growing stage and ending fast-growing stage in northern locality was earlier than that in southern locality.(5)All though traits were negatively correlated with latitude,seedling height,biomass and leaf area were positively correlated with longitude,while other traits were negatively correlated with longitude.In general M.azadarach begongs to full-time growth type with significant differences in growth traits among seed sources.The growth was regulated by both latitude and longitude,mainly by latitude.