种植密度和方式对油莎豆块茎生长期光合特性和产量的影响

作物产量与群体结构密切相关。为合理配置群体结构，提高油莎豆光能利用率并最终提高产量，研究不同群体结构对油莎豆块茎生长阶段光合特性和产量的影响，以进一步挖掘黑龙江省中西部地区油莎豆产量潜能。2018年以黑油莎2号为材料，采用三因素大田裂裂区试验设计，主区为种植密度，分别为90 000株/hm²（A1）、110 000株/hm²（A2）、130 000株/hm²（A3）；裂区为种植方式，分别为110 cm垄上三行（小行距30 cm）（B1），65 cm垄上双行（小行距20 cm）（B2），45 cm垄上单行（B3）；裂裂区为留苗方式，分别为矩形留苗（C1），三角留苗（C2），共18种处理，3次重复。通过测定群体光合速率（CAP）、叶绿素a+b（Chla+b）含量及荧光参数（Fv/Fm和qP），研究不同处理对油莎豆块茎生长阶段群体光合特性和产量形成的影响。结果发现：油莎豆块茎形成期，群体光合速率随着种植密度的增加而增大，3种密度处理间差异显著（P<0.05）；块茎增长期和成熟期，群体光合速率随着种植密度的增加呈先增后降的趋势。随着种植密度的增加，油莎豆块茎形成后0 d，冠层和下部叶片叶绿素a+b含量、最大光能转化率Fv/Fm、光化学猝灭系数qP均呈逐渐增加趋势；块茎形成后25~75 d，冠层和下部叶片叶绿素a+b含量、最大光能转化率Fv/Fm、光化学猝灭系数qP呈先增后降趋势。相同密度和留苗方式条件下，群体光合速率、叶绿素a+b含量、Fv/Fm及qP所测指标表现为种植方式B2最大，较B1、B3差异均显著（P<0.05）；相同密度和种植方式下，上述所测指标表现为留苗方式C2更大，较C1差异显著（P<0.05）。A2B1C2处理产量达到7520.45 kg/hm²，在所有处理中最高。合理的种植密度是提高油莎豆产量的关键。适宜密度下，合理的宽窄行配置和三角留苗方式可有效改善群体结构，提高群体光合速率，增加叶绿素a+b含量，提高最大光能转化率Fv/Fm和光化学猝灭系数qP，是实现植株个体与群体相互协调并提高产量的重要途径。

Effects of densities and planting mode on photosynthetic characteristics and yield of Cyperus esculentus during tuber growth stage

Crop yield is closely related to population structure, and rational population structure configuration is one of the effective ways to improve crop light energy utilization rate and increase yield. The effects of different population structures on photosynthetic characteristics and yield in tuber growth stage were studied to provide theoretical basis for further tapping yield potential of Cyperus esculentus in the midwestern of Heilongjiang Province. C. esculentus variety Heiyousha 2 was used as material in 2018. Three factors split-split plot design was used to study the effects of different population structures on photosynthetic characteristics and yield by analyzing canopy apparent photosynthetic （CAP）, Chl（a+b） content, Fv/Fm and qP. The main plots was planting density with 90 000 plants/hm² （A1）, 110 000 plants/hm² （A2）, and 130 000 plants/hm² （A3）; split plot was planting way with 110 cm ridge 3 lines （B1）, 65 cm ridge 2 lines （B2）, and 45 cm ridge 1 line （B3）. Split-split plot was seedling retention with rectangular （C1） and triangles （C2）. Results showed that CAP increased with the planting density in tuber formative stage, and the differences among 3 treatments were significant （P< 0.05）. CAP increased firstly and then decreased with the density in the middle stage of tuber growth and maturity stage. Chl（a+b） content, Fv/Fm and qP increased with the density in 0 d after tuber formative stage in canopy and lower leaves. Chl（a+b） content, Fv/Fm and qP increased firstly and then decreased with the density in 25-75 d after tuber formative stage. The changes of CAP, Chl （a+b） content, Fv/Fm and qP were in B2> B1 and B2> B3, the differences were significant （P< 0.05） under the same density and seedling retention way. The above indicators were C2>C1, the differences were significant （P< 0.05） under the same density and planting way. A2B1C2 treatment had the highest yield （7520.45 kg/hm²）. Thus a reasonable planting density would be the key to increase C. esculentus yield. Under the appropriate density, reasonable wide-narrow row configuration and triangular seedling retention ways could effectively improve the population structure, CAP, Chl（a+b） content, Fv/Fm and qP, and thus would be an important way to achieve coordination between individual plants and the population, and to increase yield.