Trinexapac‐Ethyl Effects on Red Clover Seed Crops in Diverse Production Environments

Anderson, Nicole P.; Monks, David P.; Chastain, Thomas G.; Rolston, M. P.; Garbacik, Carol J.; Ma, Chunhui; Bell, Carlos

doi:10.2134/agronj14.0399

Cited by 5 publications

(9 citation statements)

References 15 publications

(23 reference statements)

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“…Coupled with the dry and warm conditions in 2015, the reduction in canopy coverage with TE reduced the amount of soil water available for seed filling in the BBCH 32 application of TE. The reduction in height of the crop canopy by TE likely increased transmission of photosynthetic active radiation through the canopy to the soil as reported for TE treatment in red clover seed crops (Anderson et al, 2015). With wet conditions in March and April 2016, no effects of TE on soil water content were detected in early May 2016.…”

Section: Discussionmentioning

confidence: 62%

“…Furthermore, TE was not observed to cause mortality of stems. However, Anderson et al (2015) reported that stem number in red clover seed crops was increased by applications of TE PGR in New Zealand, whereas Anderson et al (2016) found that TE did not influence stem number in red clover in Oregon.…”

Section: Discussionmentioning

confidence: 99%

“…The number of inflorescences m –2 in crimson clover was not affected by TE PGR in 2015 and 2016 and could be an important reason for the lack of seed yield response to TE in those years (Table 4). Increases in inflorescences m –2 with TE PGR applications in red clover ranged from 26 to 62% (Anderson et al, 2015), and these increases contributed to greater seed yield with TE. The effects of TE application on florets inflorescence –1 were not consistent among years, with some TE rate and timing combinations increasing florets inflorescence –1 over the untreated control in 2015 but not in 2016 (Table 4).…”

Section: Discussionmentioning

confidence: 99%

“…The efficiency of dry matter partitioning to seed yield in relation to crop biomass is measured by harvest index (HI). Plant growth regulators have been used in red clover seed crops to increase HI by promoting partitioning to seed in relation to vegetative biomass and to reduce lodging (Anderson et al, 2015, 2016; Silberstein et al, 1996).…”

mentioning

confidence: 99%

“…Seed yield increases resulting from the application of these triazole inhibitors of GA biosynthesis were found to be related to greater inflorescence numbers stem –1 and greater inflorescence numbers m –2 than in untreated plots. Anderson et al (2015) reported a 9 to 16% seed yield increase in red clover across New Zealand and Oregon environments when TE was applied at Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie (BBCH) 32. Red clover seed yield was increased when TE was applied at BBCH 32 in second‐year stands but not in first‐year stands (Anderson et al, 2016).…”

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confidence: 99%

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Trinexapac‐ethyl Affects Seed Production in Crimson Clover

2019

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Core Ideas Crimson clover canopy height was reduced with trinexapac‐ethyl applications. Seeds m–2 in crimson clover was increased by trinexapac‐ethyl applications. Seed yield responses to trinexapac‐ethyl were dependent on spring weather conditions. Seed weight reductions were inversely proportional to trinexapac‐ethyl rate. This is the first study to document effects of trinexapac‐ethyl on crimson clover seed crops. ABSTRACT Trinexapac‐ethyl (TE), a plant growth regulator (PGR) and lodging‐control agent, increases seed yield in red clover (Trifolium pratense L.), but the effects of TE are unknown in crimson clover (Trifolium incarnatum L.) seed crops. The objectives of this study were to determine TE application rate and timing effects on crop canopy characteristics, seed yield, and seed yield components of crimson clover. On‐farm trials were conducted at two locations (Banks and St. Paul, OR) in 2012 and 2013 and at the Hyslop Research Farm near Corvallis, OR, in 2015 and 2016. Treatments were TE PGR application rates (0, 105, 140, 210, 280, 420, and 560 g a.i. ha−1) and two application timings (stem elongation, Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie [BBCH] 32; inflorescence emergence, BBCH 51). Application of TE PGR reduced height of the seed crop canopy. Seed yield was increased in 2012 and 2013 with rates ≤280 g TE ha−1 when applied at the BBCH 32 timing. Seed yield increases attributable to TE ranged from 12 to 36%. However, no effects of TE application on seed yield were observed in 2015 and 2016, likely as a result of dry and warm spring weather. Seed yield increases in 2012 and 2013 were a result of TE‐induced increases in seeds m−2. Seed weight was reduced by TE application, and these reductions were inversely proportional to TE rate. Seed yield responses in crimson clover to TE PGR varied across years and locations, with seed yield increases occurring in wet and cool spring weather conditions.

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Section: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Trinexapac‐ethyl Affects Seed Production in Crimson Clover

2019

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Irrigation and Trinexapac‐Ethyl Effects on Seed Yield in First‐ and Second‐Year Red Clover Stands

2016

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Irrigation and trinexapac‐ethyl (TE) [4‐(cyclopropyl‐α‐hydroxymethylene)‐3, 5‐dioxo‐cyclohexanecarboxylic acid ethylester] plant growth regulator (PGR) have been reported to enhance seed yield in red clover (Trifolium pratense L.). This study examined the interaction of irrigation and TE on seed productivity in first‐and second‐year stands in western Oregon (OR). Two field trials were established and followed over a 2‐yr period (2012–2013, 2013–2014). Treatments consisted of an untreated control, and 140, 280, 420, 560, and 700 g a.i. ha−1 TE PGR applied at BBCH growth stages 32 and 51, and in split applications at BBCH 32 + 51. A single irrigation (100 mm) applied at BBCH 55 increased seed yield and weight in first‐and second‐year stands by 13 and 5%, respectively. Seeds m−2 increased nearly 10% with irrigation in both first‐and second‐year stands in 2013 but not in 2014. Application of TE at BBCH 32 increased seed yield by 13.8% in second‐year stands, except at the 700 g a.i. ha−1 rate, and had no effect or reduced seed yield in first‐year stands. Seed weight was reduced by TE at all timings and reductions were proportional to the rate of application. Seeds m−2 increased in first‐year stands with TE rates ≥280 g a.i. ha−1 and ≥420 g a.i. ha−1 in 2012 and 2013, respectively, and with all rates in second‐year stands. There was no interaction between irrigation and TE in any year. First‐ and second‐year stands will likely benefit from irrigation; however, TE only increased seed yield in second‐year stands.Core Ideas Irrigation and trinexapac‐ethyl independently increase red clover seed yield but there is no interaction between the two. Red clover seed yield is enhanced by increasing seed weight with irrigation whereas seed weight is reduced with trinexapac‐ethyl. Irrigation increases seed yield in first‐and second‐year stands but trinexapac‐ethyl only increases seed yield in second year stands.

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Plant Growth Regulator and Irrigation Effects on Physiological and Harvest Maturity of Red Clover in Relation to Seed Quality

et al. 2019

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Core Ideas Trinexapac‐ethyl, a plant growth regulator, does not affect the quality of red clover seeds if applied at a rate of up to 700 g a.i. ha–1. Seeds reach maximum quality at harvest maturity, when seed moisture content is approximately 140 g kg–1. Visual indicators of physiological maturity of red clover include flower heads contain light brown petals and brownish‐green sepals, whereas seeds are pale green to pale yellow. At harvest maturity, heads contain dark brown petals and sepals, whereas seeds range from yellow to yellow‐dark grayish purple. A single irrigation application of water at the first flowering stage increased yield by approximately 9% in a 2‐yr study. Application of trinexapac‐ethyl at a rate of 560 g a.i. haw in the stem elongation stage increased seed yield by 16% in 1 of a 2‐yr study. Seed moisture content at physiological maturity of red clover ranges from 340 to 540 gkg–1 and approximately 140 g kg–1 at harvest maturity. Plant growth regulators (PGRs) and irrigation affect seed yield of red clover (Trifolium pretense L.). However, the effects of these factors on physiological maturity (PM), harvest maturity (HM), and seed quality are unknown. Therefore, the objectives of this study were to determine the effects of trinexapac‐ethyl (TE) PGR and irrigation on PM, HM, and seed viability and vigor on the most common red clover variety in Oregon over 2 yr. Five TE rates, ranging from 0 to 700 g a.i. ha−1, were applied at stem elongation and bud emergence stages. Irrigation was applied at the first flowering stage. Physiological and visual indicators were recorded to determine PM and HM. Standard germination (SG), tetrazolium (TZ) and cold (CT) tests were conducted to evaluate seed quality at weekly intervals starting from seed formation until HM. Irrigation resulted in a 4‐d delay in PM compared to the non‐irrigated treatment, but TE applications did not affect timing of seed maturation. At PM, flower heads contained light brown petals and brownish‐green sepals, whereas seeds were pale green to pale yellow. At HM, heads contained dark brown petals and sepals, whereas seeds ranged from yellow to yellow‐dark grayish purple. Seed dry weight did not change from PM to HM. Seed moisture content at PM ranged from 340 to 540 g kg−1 and decreased to below 140 g kg−1 at HM. At HM, seeds reached maximum quality as viability ranged from 92 to 98% by TZ and SG, and vigor ranged from 90 to 94% by CT.

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Trinexapac‐Ethyl Effects on Red Clover Seed Crops in Diverse Production Environments

Cited by 5 publications

References 15 publications

Trinexapac‐ethyl Affects Seed Production in Crimson Clover

Trinexapac‐ethyl Affects Seed Production in Crimson Clover

Irrigation and Trinexapac‐Ethyl Effects on Seed Yield in First‐ and Second‐Year Red Clover Stands

Plant Growth Regulator and Irrigation Effects on Physiological and Harvest Maturity of Red Clover in Relation to Seed Quality

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