种植密度对不同矮生型西葫芦品种冠层源库特征及产量的影响

Effect of planting density on canopy sink-source feature and yield of different dwarf varieties of summer squashes (Cucurbita pepo L.)

国内西葫芦品种有矮生和半矮生两类,半矮生品种是目前保护地主要栽培类型。试验分别以2个半矮生"东葫4号"和"冬玉"及2个矮生品种"长青王3号"和"早青"为研究对象,研究了种植密度对大棚西葫芦群体冠层、源库特征的影响,以揭示大棚西葫芦高产的关键因素。结果表明:从低密度到高密度,半矮生西葫芦品种冠层指标的变化高于矮生品种,叶面积指数(LAI)、源供应能力、库容量的变化呈二次曲线,透光率的变化与LAI趋势相反,源库比随密度由低到高呈线性变化,最适源库比下产量最高。低密度下,LAI较低,漏光损失大,源供应能力、库容量、源库比都较低,库容量小是其产量较低的主要原因;中密度下,不同生育期LAI较高,半矮生品种最大为4.4,矮生品种最大为3.3,冠层底部的透光率较小,半矮生品种平均为12.4%,矮生品种为13.2%,源足、库大且接近最大值,半矮生品种与矮生品种最大源供应能力分别为1 169.8 g.m 2、736.9g.m 2,最大库容量分别为422.4 g.m 2、333.0 g.m 2,源库比接近最适值(半矮生与矮生品种分别为2.62、1.96)是其产量高的主要原因;高密度下,结果前期LAI上升最快,达到峰值后群体底部透光率更低,结果后期下部叶片早衰,LAI下降较快,漏光损失大,源的供应能力成为高密度下限制产量的主导因素。半矮生品种较矮生品种产量高,其冠层有较高较稳的源供应能力是主要因素(半矮生品种的最大源供应能力是矮生品种的1.6倍),保护地生产应选用半矮生品种。

Dwarf and semi-dwarf varieties of summer squashes are two domestic types in China and semi-dwarf varieties are mainly cultivated under greenhouse conditions.To study the effect of density on canopy and source-sink relationship in summer squash,key high-yield factors of summer squash were tested in large plastic houses by using two semi-dwarf varieties（＂Donghu No.4＂ and ＂Dongyu＂） and two dwarf varieties（＂Changqingwang No.3＂ and ＂Zaoqing＂）.The results showed that as planting densities increased from low to high,the changes in canopy indicators of semi-dwarf varieties were far greater than those in dwarf varieties.The trends of change in LAI（leaf area index）,source capacity and sink capacity tracked quadratic-type curves.Transmittance had an inverse trend of change with LAI.The trend of change in source-sink ratio was linear and the highest yield was at optimum source-sink ratio.Lower LAI and higher light transmittance,and lower source supply,sink capacity and source-sink ratio were noted under lower density.Lower summer squash yield was associated with lower sink capacity under lower density.Light transmittance for all tested varieties was lower under medium density treatment with mean values of 12.4% for semi-dwarf and 13.2% for dwarf varieties.However,LAI was higher under medium density treatment with maximum LAI of 4.4 for semi-dwarf and 3.3 for dwarf varieties.The higher yield under medium density was associated with higher capacities of source and sink and source-sink ratio.The maximum source supply was 1 169.8 g.m 2 for semi-dwarf varieties and 736.9 g.m 2 for dwarf varieties.Also the maximum sink capacity was 422.4 g.m 2 for semi-dwarf and 333.0 g.m 2 for dwarf vine.Then the almost optimal source-sink ratio was 2.62 for semi-dwarf and 1.96 for dwarf varieties.Summer squash LAI under high density treatment increased rapidly at early growth stage with lower light transmittance especially at maximum LAI.However,LAI decreased rapidly due to rapid senescence of lower position leaves at late stage,resulting in larger light transmittance.Under high density,source supply was the dominant limiting factor of yield.Semi-dwarf varieties yield was higher than dwarf yield varieties because of higher and more stable source supply.The largest source supply capacity of semi-dwarf variety was 1.6 times that of dwarf variety.It was concluded that semi-dwarf variety of summer squash was a better choice for protected fields.