Abstract
Increase of planting density has been widely used to increase grain yield in crops. However, it may lead to higher risk of lodging hence causing significant yield loss of the crop. To investigate the effects of planting density on lodging-related morphology, lodging rate (LR), and yield of tartary buckwheat, an experiment was carried out with a split-plot randomized block design at the experimental farm of Chengdu University (Sichuan, China) in the 2012 and 2013 growing seasons. Results showed that plant density significantly affected characteristics of stem and root. In each season, with the increasing of planting density, light transmittance, main root length, number of first lateral root, root volume, internode number, and first internode diameter decreased, the plant height, first internode length, abortion rate and LR increased. Increasing density caused decreased grains number per plant, the dry matter weight and yield displayed an acceleration first and then deceleration. The correlation analysis indicated that the internode number, first internode diameter, number of first lateral roots, and root volume were significantly negatively correlated with LR, but positively correlated with stem breaking strength and lodging resistance index. The LR was significantly positively correlated with plant height and first internode length. In both years, the D2 (9 × 105 plant ha−1) and D3 (12 × 105 plant ha−1) yielded more grains than in other treatments, and the effects of density on two cultivars showed the same trend. The results suggested that planting density could alter lodging-related traits, lodging resistance, and yield of tartary buckwheat.
Highlights
The canopy light transmittance in tartary buckwheat differed with planting density in 2012 and 2013 (Figure 1)
Light transmittance clearly declined with increased planting density at both 0 and 50 cm above the ground, and light transmittance was lower at the former than the latter
At high density, intense intraspecific competition decreases the amount of light available to coexisting plants, leading to taller plants, smaller main-stem diameters, elongated lower internodes, fewer internodes, less number of first lateral root, and smaller volume (Tables 2 and 3)
Summary
In the field production of tartary buckwheat, increasing the planting density is an easy way to increase yield but often conflicts with lodging resistance, because the lodging happens easier under higher planting density (Hagiwara et al, 1999). The results of prior studies have provided useful information on the morphological traits and physiological mechanisms of lodging resistance and yield in other crops. This study was conducted to evaluate the effects of planting density on lodging-related morphological characteristics, lodging rate (LR), and yield of tartary buckwheat, and to provide a theoretical basis for high-yielding and lodging-resistance cultivation techniques for this crop
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