干旱胁迫和播种密度对洋葱小鳞茎生理特性及产出鳞茎个数的影响

Effects of drought stress and planting density on physiological characteristics and yield of onion bulblets

【目的】研究干旱胁迫和播种密度对洋葱小鳞茎生理特性及产出鳞茎个数的影响,为实现洋葱的机械化定植奠定理论和技术基础。【方法】以洋葱品种白雪为材料,采用平底育苗盘播种,设计3种播种密度处理:1.5 cm×1.5 cm(A_(1))、2 cm×2 cm(A_(2))和2.5 cm×2.5 cm(A_(3));3种干旱胁迫:田间持水量8%(B_(1))、田间持水量13%(B_(2))和自然干旱(B_(3))。【结果】随着干旱胁迫时长的增加,洋葱幼苗株高和假茎粗呈先增加后降低的趋势。适当干旱胁迫能促进地下部洋葱小鳞茎横径的生长。(2 cm×2 cm)*自然干旱(T 6)处理的洋葱可溶性固形物含量最大,为20.17%。(2 cm×2 cm)*田间持水量的8%(T_(4))处理的可溶性糖含量最大,为6.73%。随着播种密度的增加,可溶性蛋白含量和CAT活性呈增加趋势,但是差异不显著。(2 cm×2 cm)*自然干旱(T_(6))处理的POD活性最高,为23.6 U/(g·min);(1.5 cm×1.5 cm)*自然干旱(T_(3))处理的SOD活性最高,为7.560 U/(g·h)。(1.5 cm×1.5 cm)*3个干旱(T_(1)~T_(3))处理的小鳞茎个数显著多于其他处理的小鳞茎个数,产出鳞茎个数分别为36.13、35.05和35.48个/dm 2。干旱前后育苗基质的容重、总孔隙度、持水孔隙度及EC值均在理想范围内。主成分综合评价值由高到低为T_(9)>T_(8)>T_(7)>T_(1)>T_(6)>T_(4)>T_(5)>T_(2)>T_(3)。【结论】(2.5 cm×2.5 cm)*自然干旱(T_(9))处理的综合表现良好,排名第1,可作为培育洋葱小鳞茎的组合。

【Objective】This project aims to study the effects of drought stress and sowing density on the physiological characteristics and yield of onion bulblets in order to explore the use of onion bulblets as sowing materials in the hope of laying a theoretical and technical foundation for the mechanized planting of onion.【Methods】'Baixue'was used as the experimental material,and the flat-bottom seedling tray was used for sowing.Three sowing densities were designed:1.5 cm×1.5 cm(A_(1)),2 cm×2 cm(A_(2))and 2.5 cm×2.5 cm(A_(3)).Three kinds of drought stress:8%field capacity(B_(1)),13%field capacity(B_(2))and natural drought(B_(3)).【Results】With the increase of drought stress duration,the plant height and pseudostem diameter of onion seedlings increased first and then decreased.Appropriate drought stress promoted the growth of the transverse diameter of underground onion bulblets.The soluble solids content of onion treated with(2 cm×2 cm)*natural drought(T_(6))was the highest,which was 20.17%.The soluble sugar content of 8%(T_(4))treatment of(2 cm×2 cm)*field capacity was the highest,which was 6.73%.With the increase of sowing density,soluble protein content and CAT activity showed an increasing trend,but the difference was not significant.The POD activity of(2 cm×2 cm)*natural drought(T_(6))treatment was the highest,which was 23.6(U/(g·min));the highest SOD activity was 7,560(U/(g·h))under(1.5 cm×1.5 cm)*natural drought(T_(3))treatment.The number of bulblets in(1.5 cm×1.5 cm)*3 drought(T_(1)-T_(3))treatments was significantly higher than those in other treatments,and the number of bulblets per square centimeter was 36.13,35.05 and 35.48,respectively.The bulk density,total porosity,water holding porosity and EC values of the seedling substrate before and after drought were within the ideal range.The comprehensive evaluation value from high to low was T_(9)>T_(8)>T_(7)>T_(1)>T_(6)>T_(4)>T_(5)>T_(2)>T_(3).【Conclusion】The comprehensive performance of(2.5 cm×2.5 cm)*natural drought(T 9)treatment is good and ranks first,which can be used as a combination for cultivating onion bulblets.