Core Ideas Some hemp traits are more strongly affected by environmental factors than others. Multi‐environment testing is an integral part of hemp cultivar development. Water availability can have a significant impact on yield and other traits. Starting with the 2014 Farm Bill, hemp (Cannabis sativa L.) is being re‐introduced as an industrial crop in the United States. Since the crop has been absent for over 70 yr, little is known regarding the genetic mechanisms controlling economically relevant traits. Particularly, with federal legality of the crop hinging on a stringent tetrahydrocannabinol (THC) content of 0.3% or less, it is necessary to assess variance in this trait due to environmental effects and genotype × environment interactions (GEI) to avoid running afoul of federal law. Understanding how physical and biochemical traits respond to the environment also plays a strong role in selecting and developing appropriate cultivars for production in diverse growing regions. In 2016 we performed cultivar trials in multiple environments in Colorado to assess performance characteristics of a diverse set of germplasm from breeding programs across Europe and Asia. From these data, we were able to identify traits nearly entirely controlled by genetic factors, like days to maturity and THC and cannabidiol (CBD) production. We also identified traits strongly influenced by the environment and GEI, like grain yield, plant height, and water use. Individual cultivars also exhibited widely varying degrees of sensitivity to the environment. This underscores the importance of continued work to characterize genetic control of hemp traits to expedite breeding of cultivars that are well‐adapted to target growing regions.
Onion (Allium cepa L.) is a high cash value crop with a very shallow root system that is frequently irrigated and fertilized with high N rates to maximize yield. Converting from furrow-irrigated to drip-irrigated onion production may reduce N fertilizer needs, water inputs, and NO 3 -N leaching potential. Onion growth and N uptake, fresh yield, and residual soil NO 3 -N were determined under drip and furrow irrigation on a clay loam soil with N fertilizer rates from 0 to 224 kg N ha -1 . Onions were sampled bi-weekly from 25 May to 30 August in 2005 and 2006 from each treatment. In 2005, 72% less water was applied with the drip system compared with furrow system, and 57% less in 2006. Onion yields were signifi cantly greater with the drip system. Total marketable fresh onion yield increased with increasing N rate in 2005 only. Th e drip system had more colossal and jumbo sized onions and less medium sized onions than the furrow system. Biomass production and N accumulation accelerated in mid-June each year with an average total N accumulation (leaves + bulbs) of 121 kg N ha -1 at fi nal harvest. Irrigation water use effi ciency (IWUE) and N use effi ciency (NUE) were higher with the drip system than with the furrow system. Residual soil NO 3 -N levels were greater in the drip-irrigated treatments aft er onion harvest in 2005 than in the furrow-irrigated treatments, but soil NO 3 -N levels were similar aft er harvest in 2006. Adjusted gross economic returns (less the cost of N, water, and drip system) were greater with drip irrigation than with furrow irrigation. Th is study demonstrates that fresh onion yields, potential economic returns, IWUE, and NUE can be improved in Colorado by using drip irrigation for onion production rather than furrow irrigation.
Canola oil is high in oleic acid which is commonly used for food and industrial purposes. To determine adaptability of spring canola (Brassica napus L.) to the High Plains for industrial oil production, 26 irrigated trials were conducted from 2005 to 2008. Trials were divided into five regions-1: 36-37 • N 108 • W; 2: 39-40 • N 101-103 • W; 3: 41-42 • N 102-103 • W; 4: 41-42 • N 104 • W; 5: 43-44 • N 106-108 • W. Cultural practices were based on site-specific protocols. Four cultivars, Hyola 401, Hyola 357 Magnum, SW Marksman, and SW Patriot, were planted in replicated plots in April or May under standard irrigation and harvested in July to October depending on region. Seed yield Hyola 401 and Hyola 357 Magnum were higher than SW Marksman and SW Patriot across the five regions and within Regions 1, 2, 3, and 5. Regions 1, 2 and 3 yielded significantly greater than did Regions 4 and 5. Samples from 18 trials were examined for their oil content and fatty acid distribution. The four cultivars had greater than 38% oil content; SW Marksman and SW Patriot had higher oil content than Hyola 401 and Hyola 357 Mag. Higher oil content was achieved in Regions 1, 4 and 5. Across and within regions, the percent of oleic acid did not differ for the four cultivars. The mean content of oleic acid decreased going north from Region 2 to Region 5, as did seed yield in the High Plains. Linoleic acid increased going north from Region 1. Linolenic acids showed little variation across regions. Considering yield and total oil content together, growing spring canola would be excellent in the High Plains.
Nuña bean is a special market class of common bean (Phaseolus vulgaris L.) indigenous to the Andean mountains of Ecuador, Peru, and Bolivia. Nuña bean is oft en referred to as "popping" or "pop" beans because the seed expands rapidly when heated in oil. South American nuña bean cultivars are not adapted to production in the United States because they are photoperiod sensitive and have an aggressive climbing, indeterminate growth habit. Th e popping characteristic from nuña bean was successfully introgressed into 10 dry bean lines with determinate growth habit and adaptation to the temperate climates of North America. Th e objective of this research was to evaluate the nuña breeding lines for yield, popping ability, and seed size at three locations in Colorado. Two lines, CO49956 and CO49957, had the highest popping frequency (70 and 68%, respectively) among the lines tested. Mean seed yield among lines varied from 1321 to 1794 kg ha -1 and mean seed size varied from 34 to 44 g 100 seeds -1 . All lines had determinate growth habit with Type I architecture. Our fi ndings indicate that four of the lines, CO49956, CO49957, CO50004, and CO49991, were the most productive and had the highest popping frequency. Nuña popping bean has potential for commercial on-farm production in suitable temperate locations and as a commercial product to the American consumer.
The response of alfalfa (Medicago sativa L.) to phosphorus (P) and potassium (K) fertilizer often varies with soil type, the initial soil test P and K levels, irrigation and harvest management, and yield level. The objectives of this study were to determine the response of irrigated alfalfa to P and K fertilizer on a Wetherill loam soil in southwestern Colorado and to assess the impact on soil test P and K levels. Four P (0, 37, 74, and 148 kg ha 21 ) by three K (0, 93, and 186 kg ha 21 ) rates were applied to newly seeded alfalfa in the fall of 1995. An additional 37 kg P ha 21 was applied annually to half of each plot in the spring of 1997, 1998, and 1999. Potassium fertilizer increased alfalfa dry matter (DM) yield significantly in 1996 only. Alfalfa K uptake averaged 311 kg ha 21 yr 21 in 1997-1999. Soil test K level at the 0-to 30-cm depth was not impacted by K fertilization and remained above the critical level throughout the duration of the study. On the basis of these and other research results, a response to K fertilization is unlikely on most alfalfa-producing soils in Colorado because of their high K-buffering capacity. The initial application of 37 -148 kg P ha 21 did not affect alfalfa DM production signifi37 kg P ha 21 yr 21 when no P was applied initially. Both the initial and annual P fertilizer applications increased alfalfa P concentration significantly in 1997 through 1999. Alfalfa P uptake averaged 32.6 kg ha 21 yr 21 . Similarly, the initial and/or annual P application 1213 increased soil ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA) extractable P significantly in 1998 through 2000. When no P was applied, soil test P level at the 0-to 15-cm depth dropped from 8.3 mg kg 21 at the initiation of the study in August 1995 to less than 1.0 mg kg 21 at study termination in April 2000. It took a total of approximately 150 kg P ha 21 to raise soil test P to its initial level after 4 years of production. More than 260 kg P ha 21 would have been required to raise soil test P level to where a response to P fertilization would not be expected. Alfalfa yield response to P fertilizer was small even when soil test P level dropped to well below the critical level. No yield advantage was observed to maintaining soil test P above the critical level. Although not conclusive, our results indicate that annual P fertilizer applications are superior to one-time applications on our calcareous soils. More research is needed to refine P fertilizer recommendations and soil test correlation relationships for irrigated alfalfa hay production in southwestern Colorado.
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