Grain Yield and Quality of Foxtail Millet (<i>Setaria italica</i> L.) in Response to Tribenuron-Methyl

<div><p>Foxtail millet (<i>Setaria italica</i> L.) is cultivated around the world for human and animal consumption. There is no suitable herbicide available for weed control in foxtail millet fields during the post-emergence stage. In this study, we investigated the effect and safety of the post-emergence herbicide tribenuron-methyl (TBM) on foxtail millet in terms of grain yield and quality using a split-plot field design. Field experiments were conducted using two varieties in 2013 and 2014, i.e., high-yielding hybrid Zhangzagu 10 and high-quality conventional Jingu 21. TBM treatments at 11.25 to 90 g ai ha⁻¹ reduced root and shoot biomass and grain yield to varying degrees. In each of the two years, grain yield declined by 50.2% in Zhangzagu 10 with a herbicide dosage of 45 g ai ha⁻¹ and by 45.2% in Jingu 21 with a herbicide dosage of 22.5 g ai ha⁻¹ (recommended dosage). Yield reduction was due to lower grains per panicle, 1000-grain weight, panicle length, and panicle diameter. Grain yield was positively correlated with grains per panicle and 1000-grain weight, but not with panicles ha⁻¹. With respect to grain protein content at 22.5 g ai ha⁻¹, Zhangzagu 10 was similar to the control, whereas Jingu 21 was markedly lower. An increase in TBM dosage led to a decrease in grain Mn, Cu, Fe, and Zn concentrations. In conclusion, the recommended dosage of TBM was relatively safe for Zhangzagu 10, but not for Jingu 21. Additionally, the hybrid variety Zhangzagu 10 had a greater tolerance to TBM than the conventional variety Jingu 21.</p></div

Effects of tribenuron-methyl (TBM) on panicle length, panicle diameter, panicles ha⁻¹, grains per panicle, 1000-grain weight and yield of foxtail millet Jingu 21 in 2013 and 2014.

<p>Values are expressed as mean ± SD (<i>n</i> = 3). Different letters in the same column indicate significantly different at <i>P</i> = 0.05 level by Duncan’s new multiple range test. “−” represents dead plants.</p><p>Effects of tribenuron-methyl (TBM) on panicle length, panicle diameter, panicles ha⁻¹, grains per panicle, 1000-grain weight and yield of foxtail millet Jingu 21 in 2013 and 2014.</p

Effects of tribenuron-methyl (TBM) on panicle length, panicle diameter, panicles ha⁻¹, grains per panicle, 1000-grain weight and yield of foxtail millet Zhangzagu 10 in 2013 and 2014.

<p>Values are expressed as mean ± SD (<i>n</i> = 3). Different letters in the same column represent significantly different at <i>P</i> = 0.05 level by Duncan’s new multiple range test.</p><p>Effects of tribenuron-methyl (TBM) on panicle length, panicle diameter, panicles ha⁻¹, grains per panicle, 1000-grain weight and yield of foxtail millet Zhangzagu 10 in 2013 and 2014.</p

Effect of tribenuron-methyl (TBM) on foxtail millet biomass in 2013.

<p>Values represent means; vertical bars represent the standard deviation of three separate experiments. The abscissa in the figure represents the dosage of TBM expressed as g ai ha⁻¹. Dead Jingu 21 plants were observed at 90 g ai ha⁻¹ TBM.</p

Correlation coefficient between yield and panicle length, panicle diameter, panicles ha⁻¹, grains per panicle, and 1000-grain weight of foxtail millet Zhangzagu 10 and Jingu 21.

<p><i>x</i>₁ = panicle length; <i>x</i>₂ = panicle diameter; <i>x</i>₃ = panicles ha⁻¹; <i>x</i>₄ = grain per panicle; <i>x</i>₅ = 1000-grain weight; <i>x</i>₆ = yield.</p><p>* and ** represent significantly difference at <i>P</i> = 0.05 and <i>P</i> = 0.01, respectively.</p><p>Correlation coefficient between yield and panicle length, panicle diameter, panicles ha⁻¹, grains per panicle, and 1000-grain weight of foxtail millet Zhangzagu 10 and Jingu 21.</p

Effect of tribenuron-methyl (TBM) on grain protein content of foxtail millet.

<p>Values represent means; vertical bars represent the standard deviation of three separate experiments. The abscissa in the figure represents the dosage of TBM expressed as g ai ha⁻¹. Dead Jingu 21 plants were obtained at 90 g ai ha⁻¹ TBM.</p

Effect of nicosulfuron on P700 parameters in leaves of Radix Isatidis seedlings.

<p>Values represent the means and vertical bars indicate the standard deviation of three separate experiments. <i>P</i>_m, Y(I), ETR (I), Y(ND) and Y(NA) represent maximal <i>P</i>₇₀₀ change, photochemical quantum yield of PS I, PS I electron transport rate, quantum yield of non-photochemical energy dissipation due to donor side limitation in PS I, and quantum yield of non-photochemical energy dissipation due to acceptor side limitation in PS I. The abscissa in the figure represents the concentration of nicosulfuron and the unit is “mg L⁻¹”.</p

Effect of different concentrations of nicosulfuron on agronomic traits of radix isatidis seedlings.

<p>Note: The data in the table is mean ± SD. The different letters in the same column indicate significantly different at P<0.05 level by Duncan’s new multiple range test. <i>LA</i>, <i>WPFW</i>, <i>SFW</i> and <i>RFW</i> represent leaf area, the whole plant fresh weight, shoot fresh weight, and root fresh weight, respectively.</p><p>Effect of different concentrations of nicosulfuron on agronomic traits of radix isatidis seedlings.</p

Effect of different concentrations of nicosulfuron on photosynthetic characteristics in leaves of Radix isatidis seedling.

<p>Note: The data in the table is mean±SD. The different letters in the same column indicate significantly different at P<0.05 level by Duncan’s new multiple range test. <i>P</i>_n, <i>C</i>_i, <i>G</i>_s, <i>L</i>_s and <i>C</i>_i<i>/G</i>_s represent photosynthetic rate, intercellular CO₂ concentrations, stomatal conductance, stomatal limitation value, and non-stomatal limitation value, respectively.</p><p>Effect of different concentrations of nicosulfuron on photosynthetic characteristics in leaves of Radix isatidis seedling.</p

Effect of different concentrations of nicosulfuron on photosynthetic pigment content in leaves of Radix isatidis seedling.

<p>Note: The data in the table is mean ± SD. The different letters in the same column indicate significantly different at P<0.05 level by Duncan’s new multiple range test. <i>Chl</i>, <i>Chl</i> a, <i>Chl</i> b, <i>Car</i> and <i>Chl</i> a/b represent chlorophyll, chlorophyll a, chlorophyll b, carotenoid, and chlorophyll a/b, respectively.</p><p>Effect of different concentrations of nicosulfuron on photosynthetic pigment content in leaves of Radix isatidis seedling.</p