种植密度对陇东旱塬区光敏型高丹草生物学性状及产量的影响

本研究于2014、2015年连续两年选用两个品种的光敏型高丹草(Sorghum bicolor×S.sudanense)"大卡"和"海牛"在黄土高原雨养农业区,采用全膜平铺穴播的方式,以8.33万、12.50万和16.67万穴·hm-2 3个种植密度进行种植,比较了各处理的生长发育指标和草产量的异同。结果表明,在生育期方面,品种间从孕穗期开始后差异明显。在农艺性状方面,"海牛"两年的分蘖数和全株叶片数均高于"大卡",其他各性状均以"大卡"最高;两个品种的茎粗、分蘖数、全株叶片数、节间数、单株鲜重、单株叶重和单株茎重连续两年均随着密度的加大而减小,呈负相关关系;主茎叶片数随密度的增加呈先上升后下降的趋势。在产草量方面,连续两年"大卡"的鲜草产量和干物质产量均高于"海牛";鲜草产量均在8.33万穴·hm-2处理下最高,且呈现出随着密度的增加鲜草产量下降的趋势;干物质产量丰水年2014年在16.67万穴·hm-2处理下最高,欠水年2015年在12.50万穴·hm-2处理下最高。综上所述,在黄土高原雨养农业区采用全膜覆盖方式种植光敏型高丹草时,品种应选择"大卡",在有灌溉条件或降水较多的地区,以16.67万穴·hm-2种植密度为宜;而在降水较少且无灌溉条件的地区,以12.50万穴·hm-2种植密度为宜。

Effect of different planting densities on the biological characteristics and yields of photoperiod-sensitive sorghum-sudan hybrids in arid land of east Gansu

In the present study,two photoperiod-sensitive(Sorghum bicolor×S.sudanense),'Big Kahuna' and 'Monster',were planted in the rainfed region of the loess plateau at three different planting densities(83 300,125 000,and 166 700 plants per hectare)by dibbling with plastic film.The growth and development indi-ces and yields of each hybrid were measured and compared.The results showed that for the growth duration, there was a significant difference between the two hybrids after the booting stage.For the agronomic charac-ters,the numbers of tiller and whole plant leaves of'Monster'were higher than that of'Big Kahuna',where-as the other characters of 'Big Kahun'were higher than that of 'Monster'.Stem diameter,tiller number, whole plant leaf number,internode number,and leaves and stem weights per plant of the two hybrids de-creased under increasing planting density over the 2 years with a negative correlation.The leaf number of the main culm showed a trend of first increasing and then decreasing with increased density.The fresh grass and dry matter yields of 'Big Kahuna'were higher than that of 'Monster'over the 2 years and the fresh yield in the 83 000 plants per hectare density was the highest of the three densities and tended to decrease with an in-crease in density.The dry matter yield in the 166 700 plants per hectare density was higher than that of the oth-er densities during 2014,which experienced abundant rainfall,whereas the yield in the 125 000 plants per hec-tare density was higher than that of the other densities during the 2015 drought.In conclusion,when photoperi-od-sensitive S.sudangrass hybrid are planted in a rainfed region of the loess plateau by dibbling with plastic film,'Big Kahuna'should be chosen at a density of 166 700 plants per hectare in an area with good irrigation conditions or precipitation,otherwise a density of 125 000 plants per hectare should be planted.