施氮量和机插密度对钵苗机插杂交籼稻叶片光合特性及产量的影响

Effects of nitrogen application rate and mechanical-transplanting density on photosynthetic characteristics and yield of hybrid indica rice with bowl mechanical-trarsplanting method

【目的】探讨贵州喀斯特地区钵苗机插条件下施氮量和机插密度对杂交籼稻光合特性及产量的影响,为钵苗机插技术在喀斯特地区的推广应用提供理论参考和技术指导。【方法】以C两优华占为试验材料,采用裂区设计设3种机插密度水平(21.65万、16.84万和12.63万穴/ha)和4种施氮水平(0、75、150和225 kg/ha),利用LI-6400型光合作用测量仪测量主要生育期的净光合速率(Pn)、气孔导度(Gs)、胞间二氧化碳浓度(Ci)和蒸腾速率(Tr)等光合参数,计算水分利用效率和光合氮素利用效率,成熟期测产并考察产量因素。【结果】随着施氮量的增加,Pn在拔节期和孕穗期整体呈上升趋势;Gs和Tr在拔节期、孕穗期和抽穗期均呈整体上升趋势;Ci在拔节期呈先升后降的变化趋势,而在孕穗期呈下降趋势;叶片氮含量在拔节期先降低后升高,孕穗期呈上升趋势;水分利用效率和光合氮素利用效率均在抽穗期整体呈下降趋势;产量呈先升高后降低的变化趋势。随着机插密度的降低,Pn和Gs在拔节期呈上升趋势,孕穗期先升高后降低,抽穗期呈降低趋势;Ci变化不显著(P>0.05,下同);Tr在拔节期逐渐上升,孕穗期逐渐下降,抽穗期呈先降低后升高的变化趋势;叶片氮含量拔节期呈升高趋势,孕穗期和抽穗期变化不明显;水分利用效率在拔节期和孕穗期均呈整体上升趋势;光合氮素利用效率在拔节期和抽穗期均先下降后上升,孕穗期先上升后下降;产量呈降低趋势。施氮量与机插密度互作对孕穗期和抽穗期Pn、拔节期和抽穗期Gs、抽穗期Tr、主要生育期水分利用效率和光合氮素利用效率的影响均达极显著水平(P<0.01),但对产量无显著影响。相关性分析结果表明,孕穗期的Pn、Gs和Tr均与产量呈显著正相关(P<0.05)。【结论】在贵州喀斯特地区钵苗机插条件下,施氮量和机插密度分别为150 kg/ha和16.84万穴/ha时,C两优华占生育中期的光合氮素利用效率较高,产量结构优势明显,产量可达9399.26 kg/ha。

【Objective】The effects of nitrogen(N)application rate and mechanical-trarsplanting density on photosynthetic characteristics and yield of hybrid indica rice in the karst area of Guizhou were studied,in order to provide theoretical reference and guidance for the promotion and application of bowl mechanical-trarsplanting method technology in karst area.【Method】Under field experiment conditions,three density levels(216500,168400 and 126300 holes/ha)and four N rate levels(0,75,150 and 225 kg/ha)were set up using split block designs and C Liangyouhuazhan as the material.Photosynthetic parameters such as net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),transpiration rate(Tr)were measured by LI-6400 photosynthesis analyzer,and water use efficiency and photosynthetic nitrogen utilization rate were calculated,then yield was detected when harvested and yield factors were studied.【Result】With the increase of N application rate,Pn increased in the jointing stage and booting stage.Gs and Tr showed an overall upward trend at jointing stage,booting stage and heading stage,and Ci increased first and then decreased at jointing stage but decreased at the booting stage.The leaf N content decreased first and then increased at the jointing stage,and at the booting stage showed an upward trend.Water use efficiency and photosynthetic nitrogen use efficiency all showed a downward trend at the heading stage.The yield increased first and then decreased.With the decrease of mechanical-trarsplanting density,Pn and Gs increased in the jointing stage,and the booting stage increased first and then decreased,and at the heading stage showed a decreasing trend.The Ci change was not significant(P>0.05,the same below).Tr gradually increased during the jointing stage,and at the booting stage gradually decreased,and decreased and then increased at heading stage.The change trend of the N content in the jointing stage was increased.The changes at booting stage and the heading stage were not obvious.Water use efficiency in the jointing stage and the booting stage both showed a trend of increasing.Photosynthetic nitrogen use efficiency at booting stage and jointing stage decreased first and then decreased,and showed up-down trend at booting stage.The yield showed a decreasing trend.The effects of nitrogen application rate and density on the Pn at booting stage and heading stage,Gs at jointing stage and heading stage,Tr at heading stage,water use efficiency and photosynthetic nitrogen use efficiency at the main growth stages were all extremely significant(P<0.01).However,there was no significant effect on the yield.Correlation analysis showed that Pn,Gs and Tr at booting stage were significantly positively correlated with yield(P<0.05).【Conclusion】In bowl mechanical-transplanting method in karst area in Guizhou,when N application rate and mechanical-trarsplanting density are 150 kg/ha and 168400 holes/ha,photosynthetic nitrogen use efficiency of CLiangyouhuazhan at growth stage is high,and structural advantage is obvious,and the output can reach 9399.26 kg/ha.