不同密度下地膜甜菜光合、呼吸特性及其与产、质量间相关性的研究

研究了不同密度群体结构下，地膜甜菜光合及呼吸作用的日变化，不同生育期光合、呼吸作用的变化及与产量和经济性状间的相关性。结果表明：低到中等密度下（４５０００～７５０００株·ｈｍ－２）群体光合、呼吸作用日变化为双峰曲线，高密度下（１０５０００株·ｈｍ－２）为单峰曲线。中－高密度下，群体表观光合强度和呼吸强度日变化均为单峰曲线。密度越大，随生育期推进，表观光合强度下降越明显，而净光合强度则大幅度降低。密度较高，个体的生长受到显著抑制，单位面积的生物学产量明显增加。密度过大导致单根重大幅度下降，含糖量降低，产糖量反而下降。相关分析表明，地膜甜菜群体光合、呼吸作用与甜菜个体生长相关性较好而与群体含糖率、产粮糖量间相关性较差，与地上部生长相关性较好而与根部生长相关性较差。三项指标中，呼吸作用、表观光合强度与作物生长相关性好而净光合强度只与单根重有较好相关性。

Study on Characteristics of Photosynthesis and Respiration in Sugarbeet Ground covered with Plastic and Their Relationship with Yield and Quality

Diurnal change and variation in different growth period of net photosynthesis rate (NPn),respiration rate (Rs.) and apparent photosynthesis (Pn) of different population in sugarbeet ground covered with plastic and they corelationship with yield and quality were studied in the paper.The results indicated that the diurnal change of NPn and Rs appeared to be a two peak curve in 45 000 plants/hm 2 and 75 000 plants/hm 2 but it's a single peak curve in 105 000 plants/hm 2 population.With the progress of growth period,NPn,Pn and Rs decreased.The decline of Pn is high in high population whereas NPn decreased large scalely.In the high population,the growth of individual plant were declined but biomass yield per unit area were significantly increased and excessive population lead to large scalely droping of single root weight,sugar content and sugar output decreased also.The correlation analysis showed that Pn and Rs in different population is postively correlated with individual sugarbeet but have lower coefficient index with sugar content and sugar output. meanwhile,they were positively correlated with the growth of upground part and have lower coefficient index with down ground part of sugarbeet.Among the three item of NPn,Pn and Rs,Rs and Pn were positively correlated with crop growth but NPn only positively correlated with single root weight.