高油玉米源、库生理特性研究 Ⅰ.高油玉米产量受叶源的限制

Physiological Characteristics of Source and Sink in High Oil Corn Ⅰ.The Grain Yield of High Oil Corn Limited by Leaf Source Capacity

以大田放任生长的种植密度在开花期减源和半量不饱和授粉的疏库处理,比较研究了高油玉米的源、库特性。结果表明,在1 5株/m2 密度下,与普通玉米相比,高油玉米单株籽粒产量显著低于普通玉米,产量构成中穗粒数差异不显著,千粒重较低(达显著水平) ;两类型玉米的单株库容量相当,但高油玉米籽粒灌浆速率低,籽粒充实度低,单粒重对叶源相对减少(剪叶)或相对增多(疏库)的反应更为敏感,产量受到同化产物供应(叶源)相对不足的限制。高油玉米授粉后的叶面积和叶面积持续期均小,叶片含氮量和光合速率均较低,说明其产量受叶源活力(光合速率)小和叶源数量少的双重限制。

High oil corn(HOC) is a value-added corn cultivar type,which contains more oil and higher quality protein than that of normal corn (NC). HOC has not been widely planted by growers because its grain yield is lower than NC. More previous research focused on the effect of mineral nutrient,plant density on its grain yield and oil content,but little information was reported on its characteristics of source and sink. This experiment was conducted to document (1) the characteristics of source and sink and effect of altered source-sink ratio on kernel weight in HOC, (2) the limited factors of HOC grain yield which were the assimilate supply (source strength) or the inherent potential of the kernel (sink capacity). The physiological characteristics of source and sink were studied on HOC by defoliation and half pollination of the topmost ear at midsilking in field under freely growing condition. Results confirmed that,compared with NC,the grain yield of HOC was lower significantly(Table 2). As to the components of yield,the difference of 1 000-kernel weight was distinct,but not significant for the kernel number per ear(Table 2) between HOC and NC. HOC has similar potential of sink capacity per ear,but lower grain filling rate and grain filling index(Fig.1,Table 3) as compared with NC. In addition,the effect of source-sink ratio alteration on individual kernel weight was more sensitive for HOC(Fig.3),which indicated a predominant source limitation for grain yield in HOC. The leaf area (LA),leaf area duration ( LAD ),net photosynthesis rate ( P n),and leaf N concentration after flowering of HOC were poorer than that of NC(Fig.4,Fig.5). In conclusion, the grain yield of HOC was limited by both of the quantity and activity for leaf source.