Abstract
ABSTRACT Stem lodging can limit the grain yield of Tartary buckwheat (Fagopyrum tataricum), and creates difficulties in harvesting. A 2-year study was conducted to study the relationships between stem characteristics and lodging resistance in Tartary buckwheat. Six Tartary buckwheat cultivars with three stem types (short-stemmed XQ1 and CQ1; mid-length stemmed YQ1 and QK3; and tall-stemmed DAB and DN1) were used. The stem characteristics differed significantly among the three stem types. Mid-length stems had the thickest stem wall, the greatest numbers of large and small vascular bundles, and the lowest stem diameter/stem wall thickness ratio among the three stem types. Mid-length stems had the highest stem breaking strength (SBS) and stem puncture strength (SPS) among the three types of stem. The lignin content was significantly higher in mid-length stems than in tall and short stems. The activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), and cinnamyl alcohol dehydrogenase (CAD), but not 4-coumarate: CoA ligase (4CL), differed significantly among the three stem types. In correlation analyses, SBS was significantly positively correlated with stem diameter, stem wall thickness, and the number of large and small vascular bundles, but significantly negatively correlated with stem diameter/stem wall thickness and lodging rate. The lignin content was significantly positively correlated with the activities of lignin-related enzymes and with SBS and SPS, and significantly negatively correlated with lodging rate. The present study provides preliminary insights into the relationship between stem traits and lodging resistance in Tartary buckwheat, laying a foundation for a further understanding of lodging resistance. Abbreviations SBS: stem breaking strength; SPS: stem puncture strength; PAL: phenylalanine ammonia-lyase; TAL: tyrosine ammonia-lyase; CAD: cinnamyl alcohol dehydrogenase; 4CL: 4-coumarate: CoA ligase.
Highlights
Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) is an edible and medicinal crop that is native to southwestern China, northern India, Bhutan, and Nepal
The second internode was the position for testing of the stem puncture strength (SPS) and stem breaking strength (SBS) by the method of needling and snapping, which measure the maximum force instantly according to the pressure sensor
We found that the lignin content of Tartary buckwheat was positively correlated with the SBS and SPS of stems, suggesting that high lignin accumulation in Tartary buckwheat stems may increase the physical strength of the stem internode (Figure 4)
Summary
Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) is an edible and medicinal crop that is native to southwestern China, northern India, Bhutan, and Nepal. The stable production of Tartary buckwheat is difficult because this crop is prone to lodging; that is, the collapse of the stem when it cannot support its own weight. Lodging is an important constraint limiting the yield and quality of Tartary buckwheat worldwide (Zhao & Shang, 2009). Severe lodging damages or even kills the plant, leading to reductions in photosynthetic ability, grain yield, grain filling, and harvesting efficiency (Berry & Spink, 2012). Enhancing the physical strength of the stem is important for lodging resistance (Kashiwagi, Togawa & Hirotsu, 2008; Setter, Laureles & Mazaredo, 1997). Mechanical properties play an important role in determining the physical strength of the stem, which is determined by its microstructure (Duan, Wang & Wang, 2004). The ability of the Tartary buckwheat stem to withstand wind, rain, and disease
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