关键词: 玉米; 亲本; 正反交; 茎秆强度; 杂种优势

Abstract:

【Objective】To study the effects of reciprocal crosses on plant morphological characteristics, lodging resistance, heterosis and density tolerance of maize hybrid F₁.【Methods】In this experiment, two hybrids KX2564 and KX3564 with the same female parent but different male parent and their parents were selected, and the two hybrids trans-KX2564 and trans-KX3564 with the same male parent but different female parent were cultivated by backcrossing as materials with three planting densities, that was low, medium and high densities (4.5×10⁴, 9.0×10⁴ and 13.5×10⁴ plants/hm²).【Results】When the planting density increased from 4.5×10⁴ to 13.5×10⁴ plants/hm², the node thickness and dry weight per unit length of the parents and hybrids decreased significantly, the lodging resistance of stems decreased, and the lodging rate in the field increased gradually. In the orthogonal experiment, the internode thickness, dry weight per unit length of the inbred lines of the female parent were significantly higher than those of the male parent, the super father advantage was higher than the super mother advantage for hybrids, while the super mother advantage was higher than the super father advantage for internode length, the hybrid advantage of internode length decreased with increasing density. When the super father advantage of stalk puncture strength and bending strength was higher, the hybrid advantage of bending strength increased with increasing density. In reverse cross, The inverse cross combination had higher super-mother advantage in node thickness and dry weight unit node length, and the hybrid advantage in dry weight unit node length decreased with increasing planting density. The lodging rate of female was higher than that of male and hybrid, and the super-mother advantage was higher in strength. Grain per spike and 1,000-grain weight of hybrids decreased with the increase of density, and yield increased significantly with the increase of density. Grain per spike, 1,000-grain weight and yield of KX3564 were significantly higher than those of KX2564, and the hybrid advantage of yield and constitutive factors of the hybrids gradually decreased with increasing density.【Conclusion】The selection of selfed lines with short internode length, thick internode diameter, high dry weight per unit length, stalk strength and yield as the father, and high grains of ears and 1,000-grains weight as the mother is conducive to increasing the stalk resistance of hybrids and breeding resistant and high yielding dense varieties.

Key words: maize; parentage; reciprocal cross; stalk strength; hybrid advantage