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Figure 1.
Daily maximum (max) and minimum (min) air temperature (AT), relative humidity (RH), rainfall and cumulative growing degree days (GDD) during the 2020 and 2021 growing seasons in Lubbock, TX, USA.
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Figure 2.
Plant height of hemp cultivars in 2021 at Lubbock, TX, USA. Bars with same letters indicate no significant differences between treatments according to the least significant difference test at p ≤ 0.05. EC: Eletta Campana.
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Figure 3.
(a) Plant dry biomass [at 57 and 114 d after planting (DAP)] and (b) irrigation water use efficiency - IWUE of different hemp cultivars at Lubbock, TX, USA in 2020. Bars with same letters indicate no significant differences between treatments according to the least significant difference test at p ≤ 0.05. B-Lab: Bialobrzeskie.
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Figure 4.
Plant dry biomass and irrigation water use efficiency (IWUE) of hemp cultivars in 2021 at Lubbock, TX, USA. Bars with same letters indicate no significant differences between treatments according to the least significant difference test at p ≤ 0.05.
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Figure 5.
Relationship of biomass with (a) plant height and with (b) stand count during 2021 growing season in Lubbock, TX, USA.
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Parameter nutrients and soil characteristics Concentration Organic matter (%) 0.6 Soil pH 7.9 Phosphorous P1 - weak bray (ppm) 26 Phosphorous P2 - strong bray (ppm) 39 Potassium (ppm) > 700 Calcium (ppm) 2,164 Magnesium (ppm) 599 Nitrate (ppm) 26 Cation exchange capacity 17.6 meq/100 g Particle distribution (0-10 cm) Clay (%) 16.72 Sand (%) 73.21 Silt (%) 10.07 Table 1.
Soil physical and chemical properties of the study site in Lubbock, TX, USA
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Year Cultivar Region Flower type Purpose 2020 Henola Poland Monoecious Grain Bialobrzeskie Poland Monoecious Fiber, grain Jinma China Dioecious Fiber 2021 Fibranova Italy Dioecious Fiber Carmagnola Selezionata Italy Dioecious Fiber, grain Eletta Campana Italy Dioecious Fiber Yuma China Dioecious Fiber, grain Jinma China Dioecious Fiber Anka Canada Monoecious Fiber, grain Table 2.
List of hemp cultivars with their origin, type of flower and purpose in 2020 and 2021 field trials at Lubbock, TX, USA.
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Year Cultivar Seed rate
(Kg ha−1)100 seed weight (g) Stand count
(plants ha−1)2020 Henola 22.4 1.49 776,000a Bialobrzeskie 61.7 1.45 685,000ab Jinma 61.7 3.27 638,500b 2021 Fibranova 28.02 1.91 158,750b Eletta Campana 28.02 1.78 310,000a Carmagnola Selezionata 28.02 − − Yuma 28.02 4.49 337,500a Jinma 28.02 3.27 361,250a Anka 28.02 − − Table 3.
Seed rate, 100-seed weight and stand count of hemp cultivars in 2020 and 2021 at Lubbock, TX, USA.
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Germination % Temperature (day/night) (T) 10/5 °C 64.8a 15/10 °C 64.4a 20/15 °C 66.0a 25/20 °C 66.9a 30/25 °C 66.7a 35/30 °C 47.8b Cultivar (C) BLAB 70.61a Carmagnola Selezionata 74.57a Henola 71.94a Jinma 33.91b T × C NS 'T × C' indicates temperature into cultivar interaction and 'NS' indicates non-significant at p ≤ 0.05. Mean values followed by the same letter in each column within a factor are not significantly different according to the least significant difference test at p ≤ 0.05. Table 4.
Effect of temperature on germination percentage across four cultivars of industrial hemp at Lubbock, TX, USA.
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Cultivars Speed of germination index (day−1) 10 °C 15 °C 20 °C 25 °C 30 °C 35 °C Average Jinma 1.96cA 1.82bA 3.74bA 3.08cA 3.97cA 2.17bA 2.82c Henola 5.91abC 6.50aBC 7.02abB 10.37aA 10.88aA 4.17abD 7.70ab B-Lab 4.81bC 6.85aABC 8.07aAB 8.18bAB 8.59bA 6.39aBC 7.16b CS 6.67aB 6.27aB 7.31aB 9.99abA 11.48aA 7.04aB 8.31a Average 4.84D 5.36D 6.54C 7.91B 8.73A 4.94D Values within a column followed by same lowercase letters are not significantly different at p ≤ 0.05. Values within a row followed by same uppercase letters are not significantly different at p ≤ 0.05. B-Lab: Bialobrzeskie, CS: Carmagnola Selezionata. Table 5.
Interaction effects of temperature and cultivar on speed of germination index of four hemp cultivars grown in a growth chamber at temperature range of 10−35 °C at Lubbock, TX, USA.
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Cultivars Mean germination time (d) 10 °C 15 °C 20 °C 25 °C 30 °C 35 °C Average Jinma 7.10aA 7.15aA 5.18aB 5.07aB 3.20aC 2.92aC 5.10a Henola 4.73bA 4.78bA 3.61bB 2.78bC 2.57aC 2.62aC 3.49bc B-Lab 5.78abA 4.03cB 3.89bBC 3.75bBC 2.83aC 2.89aBC 3.90b CS 4.46bA 4.15bcA 3.71bAB 2.91bBC 2.66aC 2.73aC 3.42c Average 5.52A 5.02A 4.09B 3.63B 2.82C 2.79C Values within a column followed by same lowercase letters are not significantly different at p ≤ 0.05. Values within a row followed by same uppercase letters are not significantly different at p ≤ 0.05. B-Lab: Bialobrzeskie, CS: Carmagnola Selezionata. Table 6.
Interaction effects of temperature and cultivar on mean germination time of four hemp cultivars grown in a growth chamber at temperature range of 10−35 °C at Lubbock, TX, USA.
Figures
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Tables
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