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Damián A. Ravetta - One of the best experts on this subject based on the ideXlab platform.

  • seed yield and yield components response to source sink ratio in annual and perennial species of Lesquerella brassicaceae
    Industrial Crops and Products, 2011
    Co-Authors: W.j. Masnatta, Damián A. Ravetta
    Abstract:

    Although the annual Lesquerella fendleri is the prime candidate for the development of a lesquerolic rich oil-seed crop, within this genus there are other species available to breeders, some of which are perennials. However, the feasibility of a perennial crop of Lesquerella is not clear because increases in seed-yield tend to reduce perennially. The objective of this work was to determine the effect of the source–sink ratio on seed yield and yield components in annual and perennial species of Lesquerella. We predicted that (i) due to differences in allocation patterns of annual and perennial species, seed-yield and yield components in perennials would be less affected by the source–sink ratio (higher stability) than in annuals and (ii) since seed-weight has been found to be the most stable yield component in other crops and their wild relatives, most of the variation in seed-yield as a consequence of source–sink ratios would be determined by changes in the number fruits per plant and the number of seeds per fruit. A field experiment was carried out in Chubut, Patagonia Argentina in a complete randomized design with four treatments to examine source–sink relationships in four species of Lesquerella, two annuals (L. angustifolia, L. gracilis) and two perennials (L. pinetorum, L. mendocina). We used either shading (reduction of source) or removal of flower-buds (reduction of sink) to develop a range of source–sink relationships. All four species showed a similar yield response to source–sink variations. Seed-yield was lower in shaded plants, although the timing of shading influenced this response. Flower-bud removal resulted in a significant increase in seed-yield. Seed-yield differences among source–sink treatments were best explained by changes in the number of fruits per plant than by the number of seeds per fruit. Source–sink manipulations had no affect on seed weight. Flower-bud removal significantly increased the number of fruits per plant in all species except for L. mendocina. The number of seeds per fruits increased only in L. pinetorum. Our results show that carbon stored during pre-anthesis plays a key role in reproduction both in annual and perennial Lesquerella. The increase in the seed-yield components found with bud removal could potentially reduce longevity in perennial species. The results also show that the number of fruits per plant is a good proxy for seed-yield within a species.

  • Relationships between reproductive output, morpho-physiological traits and life span in Lesquerella (Brassicaceae)
    Industrial Crops and Products, 2011
    Co-Authors: Luciana González-paleo, Damián A. Ravetta
    Abstract:

    The development of perennial industrial crops could contribute to increase agriculture sustainability and yield stability in arid environments. Since perennial plants allocate resources preferentially to perpetuation and to structural and functional characters that provide drought tolerance, they tend to have lower reproductive output (yield) than their congeneric annuals. Four species of Lesquerella native to arid regions were evaluated to understand the relationships between reproduction, drought tolerance, and their association with the plant's life span. We assessed the following set of characters (defined as plant strategies): phenology, gas exchange, specific leaf area, leaf area ratio, total biomass and biomass allocation. Annual (Lesquerella gracilis and Lesquerella angustifolia) and perennial (Lesquerella mendocina and Lesquerella pinetorum) species were compared under water limiting conditions. Within this set of species differences in structural and functional characters were observed. The annual, L. gracilis showed a plant strategy characterized by high reproductive output, harvest index (HI) and specific leaf area (SLA). L. mendocina (perennial), produced more total biomass, but had a low reproductive output, and also showed characters that provide drought tolerance (high allocation to roots-root mass ratio (RMR), and storage-total non structural carbohydrates (TNC) and low SLA). The annual L. angustifolia and the perennial L. pinetorum had intermediate plant strategies (i.e. intermediate values of traits typically related with annual or perennial life span). In the case of L. pinetorum we found some traits common to L. mendocina: long vegetative period, high biomass, CO2 assimilation rate (A), and water use efficiency (WUE), and low SLA. The high reproductive output in L. pinetorum was a result of both, higher total biomass and longer growing season compared to the annuals, and of higher HI in relation to the other perennial. These differences in plant strategies among perennial Lesquerella show that there are different combinations of traits that could be used as criteria for the selection of a perennial crop in programs of domestication for Patagonia and others arid lands.

  • Seed-yield and yield components response to source–sink ratio in annual and perennial species of Lesquerella (Brassicaceae)
    Industrial Crops and Products, 2011
    Co-Authors: W.j. Masnatta, Damián A. Ravetta
    Abstract:

    Although the annual Lesquerella fendleri is the prime candidate for the development of a lesquerolic rich oil-seed crop, within this genus there are other species available to breeders, some of which are perennials. However, the feasibility of a perennial crop of Lesquerella is not clear because increases in seed-yield tend to reduce perennially. The objective of this work was to determine the effect of the source–sink ratio on seed yield and yield components in annual and perennial species of Lesquerella. We predicted that (i) due to differences in allocation patterns of annual and perennial species, seed-yield and yield components in perennials would be less affected by the source–sink ratio (higher stability) than in annuals and (ii) since seed-weight has been found to be the most stable yield component in other crops and their wild relatives, most of the variation in seed-yield as a consequence of source–sink ratios would be determined by changes in the number fruits per plant and the number of seeds per fruit. A field experiment was carried out in Chubut, Patagonia Argentina in a complete randomized design with four treatments to examine source–sink relationships in four species of Lesquerella, two annuals (L. angustifolia, L. gracilis) and two perennials (L. pinetorum, L. mendocina). We used either shading (reduction of source) or removal of flower-buds (reduction of sink) to develop a range of source–sink relationships. All four species showed a similar yield response to source–sink variations. Seed-yield was lower in shaded plants, although the timing of shading influenced this response. Flower-bud removal resulted in a significant increase in seed-yield. Seed-yield differences among source–sink treatments were best explained by changes in the number of fruits per plant than by the number of seeds per fruit. Source–sink manipulations had no affect on seed weight. Flower-bud removal significantly increased the number of fruits per plant in all species except for L. mendocina. The number of seeds per fruits increased only in L. pinetorum. Our results show that carbon stored during pre-anthesis plays a key role in reproduction both in annual and perennial Lesquerella. The increase in the seed-yield components found with bud removal could potentially reduce longevity in perennial species. The results also show that the number of fruits per plant is a good proxy for seed-yield within a species.

  • development of alternative Lesquerella species in patagonia argentina potential of Lesquerella angustifolia
    Industrial Crops and Products, 2003
    Co-Authors: Edmundo Leonardo Ploschuk, David A Dierig, G. Cerdeiras, Liliana B. Windauer, Damián A. Ravetta
    Abstract:

    The genus Lesquerella is a promising source of hydroxy fatty acid (HFA). Within this genus, Lesquerella fendleri is a good candidate for domestication in the arid southwestern United States because it has high seed and oil yields, low seed dormancy, and low fruit dehiscence. Other species of Lesquerella, however, could be developed and expanded for other regions of the world with different climatic and environmental conditions. The objective of this study was to test the yield and oil content of several Lesquerella species in the Chubut River Valley, Patagonia, Argentina. The area is characterized by low temperatures during winter and high temperatures and radiation during summer. Two experiments were conducted for two consecutive years. Seed yield and oil content were determined for seven species of Lesquerella. In the first year, both fall and spring sowings were measured for all tested species. During the second year, Lesquerella angustifolia performance was evaluated together with three different accessions of L. fendleri. Spring sowings reduced seed and oil yield about 80% in L. fendleri and L. gordonii (average of the two species, P<0.05) compared with the fall sowings. These results were presumably caused by the longer daylength period during the summer at these latitudes compared with other sites. Yield was higher in L. angustifolia than other species and three times higher than L. fendleri, which was sown at the same time. The higher yield obtained with L. angustifolia was the result of the combination of both high seed weight and seed number per plant. When L. angustifolia was compared with L. fendleri germplasm originated from arid environments and with two accessions of the same species collected from high elevations, the better performance of the former was confirmed. These results clearly demonstrate that L. angustifolia performs better than L. fendleri in the irrigated valleys of Patagonia, and also that L. fendleri yields would be low under environments with very cold winters and high latitudes. Thus, fall plantings of L. angustifolia could be considered as an alternative source of HFA at this site and other similar high-latitude environments.

  • Development of alternative Lesquerella species in Patagonia (Argentina): potential of Lesquerella angustifolia
    Industrial Crops and Products, 2003
    Co-Authors: Edmundo Leonardo Ploschuk, David A Dierig, G. Cerdeiras, Liliana B. Windauer, Damián A. Ravetta
    Abstract:

    The genus Lesquerella is a promising source of hydroxy fatty acid (HFA). Within this genus, Lesquerella fendleri is a good candidate for domestication in the arid southwestern United States because it has high seed and oil yields, low seed dormancy, and low fruit dehiscence. Other species of Lesquerella, however, could be developed and expanded for other regions of the world with different climatic and environmental conditions. The objective of this study was to test the yield and oil content of several Lesquerella species in the Chubut River Valley, Patagonia, Argentina. The area is characterized by low temperatures during winter and high temperatures and radiation during summer. Two experiments were conducted for two consecutive years. Seed yield and oil content were determined for seven species of Lesquerella. In the first year, both fall and spring sowings were measured for all tested species. During the second year, Lesquerella angustifolia performance was evaluated together with three different accessions of L. fendleri. Spring sowings reduced seed and oil yield about 80% in L. fendleri and L. gordonii (average of the two species, P

David A Dierig - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of the safety and efficacy of Lesquerella fendleri seed and oils as poultry feed additives
    2015
    Co-Authors: Ross C. Beier, Terry A. Isbell, Roque L. Evangelista, Leon F. Kubena, Jackson L. Mcreynolds, Allen J. Byrd, Michael E. Hume, David A Dierig
    Abstract:

    Lesquerella (Lesquerella fendleri (Gray) Wats) is an oil seed plant capable of growth over a large geographic area of the southwestern U.S. The seed oil contains hydroxyfatty acids, useful in a variety of industrial products, and can replace imported castor bean oil (Ricinus communis L.). Lesquerella is also rich in high-quality protein with a well-balanced amino acid composition. We investigated the potential of using Lesquerella as an ingredient in poultry feed. An increase from 5% to 20% whole Lesquerella seed supplemented diet resulted in a negative linear effect on poultry weight gain at P < 0.001, and had no effect on recoverable Salmonella from the ceca of Salmonella challenged chicks. Lesquerella oil supplementation of feed reduced weight gain of the chicks, P < 0.0058, and also did not reduce Salmonella in challenged birds. However, there was no difference in weight gain between control birds and those receiving 2.5% or 5% dehulled Lesquerella seed. A small increase in feed conversion was observed, 2.35 ± 0.05 for controls, 2.47± 0.10 for the 2.5% dehulled Lesquerella seed group, and 2.53 ± 0.15 for birds receiving 5% dehulled Lesquerella seed. There appears to be no toxicity associated with dehulled Lesquerella seed. We hypothesize that utilization of Lesquerella fendleri dehulled seed, after further processing to remove the excess cellulosic materials and valuable oils, will be an additional protein product useful as a poultry feed component, and could therefore add to the economic value of the plant.

  • Lesquerella: New crop development and commercialization in the U.S.
    Industrial Crops and Products, 2011
    Co-Authors: David A Dierig, D. T. Ray, William B. Mccloskey, Terry A. Isbell, G Wang, Kelly R. Thorp, M A Foster
    Abstract:

    While Lesquerella fendleri Gray (Wats.) is not yet a commercial crop, its history serves as a model for new crop development. The most important characteristic is the absence of any significant biological barriers to commercialization. Other potential crops may have valuable, high-demand products but possess traits difficult to overcome such as seed shattering or poor yield capacity. Lesquerella has a distinctive plant architecture that is conducive to seed productivity under a variety of conditions, and the trait could be further exploited. The plant also has high amounts of within-species and interspecific genetic diversity allowing breeding improvements in traits including oil quantity and quality. The unique seed oil is predominately composed of a hydroxy fatty acid, lesquerolic acid (C20:1OH), that is similar to ricinoleic acid (C18:1OH) found in castor oil. Improvements in agronomics will help increase seed yields, water use efficiency, while reducing crop production costs. New tools offered by remote sensing will help plant breeders and growers assess crop development. Defining herbicides and obtaining registrations for use in Lesquerella appears to be the biggest obstacle for commercialization of this crop. The improvements in agronomics, breeding, genetics, and the expansion of new markets started in the 1980's, and has made Lesquerella a viable potential crop that could utilize thousands of hectares in arid climates of the world provided research continues. © 2010.

  • Color image segmentation approach to monitor flowering in Lesquerella
    Industrial Crops and Products, 2011
    Co-Authors: Kelly R. Thorp, David A Dierig
    Abstract:

    Abstract Lesquerella ( Lesquerella fendleri (Gray) Wats.) seed oil has been proposed as a petroleum alternative in the production of many industrial products, but several crop management and breeding challenges must be addressed before the crop will be grown commercially. Lesquerella canopies characteristically exhibit quite prominent and vibrant yellow flowers at anthesis, and remote detection of Lesquerella flowering patterns can provide useful crop development information to aid management and breeding decisions. In the present study, we used a consumer-grade digital camera to collect images 2 m above Lesquerella canopies throughout two growing seasons. Biomass samples within 0.125 m 2 areas were also regularly collected and processed to obtain flower numbers. Image processing algorithms were developed to extract information on Lesquerella flower features from the images. Key features of the image processing approach included an image transformation to the hue, saturation, and intensity (HSI) color space and a Monte Carlo approach to address uncertainty in HSI parameters used for image segmentation. Flower numbers were estimated from image-based flower cover percentage with root mean squared errors that ranged from 159 to 194 flowers, which was better than the reported results for other studies with a similar objective. Attempts to resolve individual flowers were less successful due to the complexity of the flowering patterns within the image scenes. Digital imaging offers an inexpensive and quite practical means for remote monitoring of flowering patterns in Lesquerella canopies.

  • Analysis of hyperspectral reflectance data for monitoring growth and development of Lesquerella
    Industrial Crops and Products, 2011
    Co-Authors: Kelly R. Thorp, David A Dierig, Andrew N. French, D. J. Hunsaker
    Abstract:

    Abstract Seed oil from Lesquerella (Lesquerella fendleri (Gray) Wats.) is currently being developed as a biorenewable petroleum substitute, but several issues related to crop management and breeding must be resolved before the crop will be commercially viable. Due particularly to the prominent yellow flowers exhibited by Lesquerella canopies, remote sensing may be a useful tool for monitoring and managing the crop. In this study, we used a hand-held spectroradiometer to measure spectral reflectance over Lesquerella canopies in 512 narrow wavebands from 268 to 1095 nm over two growing seasons at Maricopa, Arizona. Biomass samples were also regularly collected and processed to obtain aboveground dry weight, flower counts, and silique counts. Partial least squares regression was used to develop predictive models for estimating the three Lesquerella biophysical variables from canopy spectral reflectance. For model fitting and model testing, the root mean squared prediction errors between measured and modeled aboveground dry weight, flower counts, and silique counts were 2.1 and 2.3 Mg ha−1, 251 and 304 flowers, and 1018 and 1019 siliques, respectively. Analysis of partial least squares regression coefficients and loadings highlighted the most sensitive spectral wavebands for estimating each biophysical variable. For example, the flower count model heavily emphasized the reflectance of yellow light at 583 nm, and contrasted that with reflectance in the blue (483 nm) and at the red edge (721 nm). Because of the indeterminate nature of Lesquerella flowering patterns, remote sensing methods that monitor flowering progression may aid management decisions related to the timing of irrigations, desiccant application, and crop harvest.

  • New Crops Breeding: Lesquerella
    Oil Crops, 2009
    Co-Authors: David A Dierig, Dennis T. Ray
    Abstract:

    Lesquerella species contain a seed oil which is approximately 55% lesquerolic acid, a 20-carbon long fatty acid with a single hydroxyl group and double bond, and has a similar hydroxy fatty acid (HFA) profile as castor oil. Large markets exist for hydroxylated oils as feedstocks for lithium greases, polymers in paints and coatings, base stocks for lubricants, nylon-11, hydraulic fluids, and applications in the personal care industry (Roetheli et al. 1992). The hydroxyl group of these oils makes them prime candidates as additives to diesel fuel to improve lubricity (Naughton 1992). Goodrum and Geller (2005) demonstrated that Lesquerella oil has superior performance compared to castor, soybean, and rapeseed methyl esters at concentrations as low as 0.25% in reducing wear and damage to diesel engines, primarily with fuel injection systems. Castor oil also contains high amounts of HFAs, but the main HFA, ricinoleic acid, is two carbons shorter than lesquerolic acid, which imparts slightly different physicochemical properties to the oil. Lesquerella could be established as a reliable, domestic oilseed supply of HFAs for a variety of industrial applications (Roetheli et al. 1992) and at the same time provide an alternative crop for farmers and increase local profits. Lesquerella will not replace current commodity crops but instead will be placed in a rotation with these crops, e.g., a 2-year, 3-crop rotation of Lesquerella, grain sorghum, and cotton.

Amanda B. Cemper - One of the best experts on this subject based on the ideXlab platform.

W.j. Masnatta - One of the best experts on this subject based on the ideXlab platform.

  • seed yield and yield components response to source sink ratio in annual and perennial species of Lesquerella brassicaceae
    Industrial Crops and Products, 2011
    Co-Authors: W.j. Masnatta, Damián A. Ravetta
    Abstract:

    Although the annual Lesquerella fendleri is the prime candidate for the development of a lesquerolic rich oil-seed crop, within this genus there are other species available to breeders, some of which are perennials. However, the feasibility of a perennial crop of Lesquerella is not clear because increases in seed-yield tend to reduce perennially. The objective of this work was to determine the effect of the source–sink ratio on seed yield and yield components in annual and perennial species of Lesquerella. We predicted that (i) due to differences in allocation patterns of annual and perennial species, seed-yield and yield components in perennials would be less affected by the source–sink ratio (higher stability) than in annuals and (ii) since seed-weight has been found to be the most stable yield component in other crops and their wild relatives, most of the variation in seed-yield as a consequence of source–sink ratios would be determined by changes in the number fruits per plant and the number of seeds per fruit. A field experiment was carried out in Chubut, Patagonia Argentina in a complete randomized design with four treatments to examine source–sink relationships in four species of Lesquerella, two annuals (L. angustifolia, L. gracilis) and two perennials (L. pinetorum, L. mendocina). We used either shading (reduction of source) or removal of flower-buds (reduction of sink) to develop a range of source–sink relationships. All four species showed a similar yield response to source–sink variations. Seed-yield was lower in shaded plants, although the timing of shading influenced this response. Flower-bud removal resulted in a significant increase in seed-yield. Seed-yield differences among source–sink treatments were best explained by changes in the number of fruits per plant than by the number of seeds per fruit. Source–sink manipulations had no affect on seed weight. Flower-bud removal significantly increased the number of fruits per plant in all species except for L. mendocina. The number of seeds per fruits increased only in L. pinetorum. Our results show that carbon stored during pre-anthesis plays a key role in reproduction both in annual and perennial Lesquerella. The increase in the seed-yield components found with bud removal could potentially reduce longevity in perennial species. The results also show that the number of fruits per plant is a good proxy for seed-yield within a species.

  • Seed-yield and yield components response to source–sink ratio in annual and perennial species of Lesquerella (Brassicaceae)
    Industrial Crops and Products, 2011
    Co-Authors: W.j. Masnatta, Damián A. Ravetta
    Abstract:

    Although the annual Lesquerella fendleri is the prime candidate for the development of a lesquerolic rich oil-seed crop, within this genus there are other species available to breeders, some of which are perennials. However, the feasibility of a perennial crop of Lesquerella is not clear because increases in seed-yield tend to reduce perennially. The objective of this work was to determine the effect of the source–sink ratio on seed yield and yield components in annual and perennial species of Lesquerella. We predicted that (i) due to differences in allocation patterns of annual and perennial species, seed-yield and yield components in perennials would be less affected by the source–sink ratio (higher stability) than in annuals and (ii) since seed-weight has been found to be the most stable yield component in other crops and their wild relatives, most of the variation in seed-yield as a consequence of source–sink ratios would be determined by changes in the number fruits per plant and the number of seeds per fruit. A field experiment was carried out in Chubut, Patagonia Argentina in a complete randomized design with four treatments to examine source–sink relationships in four species of Lesquerella, two annuals (L. angustifolia, L. gracilis) and two perennials (L. pinetorum, L. mendocina). We used either shading (reduction of source) or removal of flower-buds (reduction of sink) to develop a range of source–sink relationships. All four species showed a similar yield response to source–sink variations. Seed-yield was lower in shaded plants, although the timing of shading influenced this response. Flower-bud removal resulted in a significant increase in seed-yield. Seed-yield differences among source–sink treatments were best explained by changes in the number of fruits per plant than by the number of seeds per fruit. Source–sink manipulations had no affect on seed weight. Flower-bud removal significantly increased the number of fruits per plant in all species except for L. mendocina. The number of seeds per fruits increased only in L. pinetorum. Our results show that carbon stored during pre-anthesis plays a key role in reproduction both in annual and perennial Lesquerella. The increase in the seed-yield components found with bud removal could potentially reduce longevity in perennial species. The results also show that the number of fruits per plant is a good proxy for seed-yield within a species.

Kelly R. Thorp - One of the best experts on this subject based on the ideXlab platform.

  • Lesquerella seed yield estimation using color image segmentation to track flowering dynamics in response to variable water and nitrogen management
    Industrial Crops and Products, 2016
    Co-Authors: Kelly R. Thorp, Guangyao Wang, Mohammad Badaruddin, Kevin F. Bronson
    Abstract:

    Abstract Seed oil from Lesquerella ( Physaria fendleri (Gray) O’Kane & Al-Shehbaz) can potentially supplement castor oil as a non-petroleum-based chemical feedstock in the production of many industrial products. However, before Lesquerella will become commercially viable, further efforts are needed to address crop management challenges and to improve Lesquerella varieties. Because Lesquerella develops vibrant yellow flowers on top of the canopy, digital imaging can be used to track the dynamics of its indeterminate flowering period. The objective of this study was to investigate a digital image analysis approach to (1) assess differences in Lesquerella flowering dynamics due to variable water and nitrogen (N) management and (2) estimate Lesquerella seed yield from flowering data. During the winters of 2011–2012 and 2012–2013, field experiments tested Lesquerella responses to two irrigation levels and six N fertilization rates at Maricopa, Arizona. Biomass was sampled within a 30 cm × 30 cm area twice per month, and Lesquerella flowers were manually counted. Twice per week, digital images were collected with a commercial digital camera at a nadir view angle approximately 2 m above the canopy. To obtain the percentage of yellow flowers in each image, an analysis routine included (1) an image transformation to the hue, saturation, and intensity (HSI) color space and (2) a Monte Carlo approach to address uncertainty in HSI parameters used for image segmentation. The imposed irrigation and N fertilization treatments led to differences in both flower count and flower cover ( p r 2  ≤ 0.84) from images as compared to manual flower counts ( r 2  ≤ 0.56). Overall, the digital imaging approach provided useful information on Lesquerella flowering dynamics, which was affected by water and N management and highly correlated with seed yield.

  • Lesquerella seed and oil yield response to split-applied N fertilizer
    Industrial Crops and Products, 2014
    Co-Authors: Jiangang Liu, William B. Mccloskey, Kelly R. Thorp, Mohammad Badaruddin, Kevin F. Bronson, Jarai Mon, Dennis T. Ray, Qingquan Chu, Guangyao Wang
    Abstract:

    Abstract Agronomic management information is critical for successful commercial production of new crops such as Lesquerella [Physaria fendleri (A. Gray) O’Kane & Al-Shehbaz]. Response of Lesquerella to six nitrogen (N) fertilizer rates under well-watered and water-stressed treatments were studied in irrigated desert conditions in the southwestern United States to establish guidelines for Lesquerella N management. Seed and oil yield, seed and straw N concentrations, N harvest index, and total N uptake were recorded at harvest and destructive biomass samples were also collected during growing season for plant N status. Although soil NO3-N was low due to a cover crop to remove excessive N in the soil, pre-plant N fertilizer did not affect Lesquerella growth at the early growth stage. For the treatments with high N fertilizer rates (224 and 336 kg ha−1), Lesquerella plant N concentrations were relatively stable before the first bloom, decreased drastically until mid-bloom (one month after the first bloom), and then continued to decrease at a lower rate until harvest. As N fertilizer rates increased, seed and straw N concentration increased linearly under both well-watered and water-stressed conditions. Lesquerella seed and oil yield had a quadratic relationship with N fertilizer rate. Because seed oil concentration decreased as N fertilizer increased, N fertilizer rate for the optimum oil yield was lower than the N fertilizer rate for the optimum seed yield. According to seed and oil yield as well as plant N status under different N fertilizer rates, we provided a guideline for N fertilizer management for Lesquerella.

  • Lesquerella: New crop development and commercialization in the U.S.
    Industrial Crops and Products, 2011
    Co-Authors: David A Dierig, D. T. Ray, William B. Mccloskey, Terry A. Isbell, G Wang, Kelly R. Thorp, M A Foster
    Abstract:

    While Lesquerella fendleri Gray (Wats.) is not yet a commercial crop, its history serves as a model for new crop development. The most important characteristic is the absence of any significant biological barriers to commercialization. Other potential crops may have valuable, high-demand products but possess traits difficult to overcome such as seed shattering or poor yield capacity. Lesquerella has a distinctive plant architecture that is conducive to seed productivity under a variety of conditions, and the trait could be further exploited. The plant also has high amounts of within-species and interspecific genetic diversity allowing breeding improvements in traits including oil quantity and quality. The unique seed oil is predominately composed of a hydroxy fatty acid, lesquerolic acid (C20:1OH), that is similar to ricinoleic acid (C18:1OH) found in castor oil. Improvements in agronomics will help increase seed yields, water use efficiency, while reducing crop production costs. New tools offered by remote sensing will help plant breeders and growers assess crop development. Defining herbicides and obtaining registrations for use in Lesquerella appears to be the biggest obstacle for commercialization of this crop. The improvements in agronomics, breeding, genetics, and the expansion of new markets started in the 1980's, and has made Lesquerella a viable potential crop that could utilize thousands of hectares in arid climates of the world provided research continues. © 2010.

  • Color image segmentation approach to monitor flowering in Lesquerella
    Industrial Crops and Products, 2011
    Co-Authors: Kelly R. Thorp, David A Dierig
    Abstract:

    Abstract Lesquerella ( Lesquerella fendleri (Gray) Wats.) seed oil has been proposed as a petroleum alternative in the production of many industrial products, but several crop management and breeding challenges must be addressed before the crop will be grown commercially. Lesquerella canopies characteristically exhibit quite prominent and vibrant yellow flowers at anthesis, and remote detection of Lesquerella flowering patterns can provide useful crop development information to aid management and breeding decisions. In the present study, we used a consumer-grade digital camera to collect images 2 m above Lesquerella canopies throughout two growing seasons. Biomass samples within 0.125 m 2 areas were also regularly collected and processed to obtain flower numbers. Image processing algorithms were developed to extract information on Lesquerella flower features from the images. Key features of the image processing approach included an image transformation to the hue, saturation, and intensity (HSI) color space and a Monte Carlo approach to address uncertainty in HSI parameters used for image segmentation. Flower numbers were estimated from image-based flower cover percentage with root mean squared errors that ranged from 159 to 194 flowers, which was better than the reported results for other studies with a similar objective. Attempts to resolve individual flowers were less successful due to the complexity of the flowering patterns within the image scenes. Digital imaging offers an inexpensive and quite practical means for remote monitoring of flowering patterns in Lesquerella canopies.

  • Analysis of hyperspectral reflectance data for monitoring growth and development of Lesquerella
    Industrial Crops and Products, 2011
    Co-Authors: Kelly R. Thorp, David A Dierig, Andrew N. French, D. J. Hunsaker
    Abstract:

    Abstract Seed oil from Lesquerella (Lesquerella fendleri (Gray) Wats.) is currently being developed as a biorenewable petroleum substitute, but several issues related to crop management and breeding must be resolved before the crop will be commercially viable. Due particularly to the prominent yellow flowers exhibited by Lesquerella canopies, remote sensing may be a useful tool for monitoring and managing the crop. In this study, we used a hand-held spectroradiometer to measure spectral reflectance over Lesquerella canopies in 512 narrow wavebands from 268 to 1095 nm over two growing seasons at Maricopa, Arizona. Biomass samples were also regularly collected and processed to obtain aboveground dry weight, flower counts, and silique counts. Partial least squares regression was used to develop predictive models for estimating the three Lesquerella biophysical variables from canopy spectral reflectance. For model fitting and model testing, the root mean squared prediction errors between measured and modeled aboveground dry weight, flower counts, and silique counts were 2.1 and 2.3 Mg ha−1, 251 and 304 flowers, and 1018 and 1019 siliques, respectively. Analysis of partial least squares regression coefficients and loadings highlighted the most sensitive spectral wavebands for estimating each biophysical variable. For example, the flower count model heavily emphasized the reflectance of yellow light at 583 nm, and contrasted that with reflectance in the blue (483 nm) and at the red edge (721 nm). Because of the indeterminate nature of Lesquerella flowering patterns, remote sensing methods that monitor flowering progression may aid management decisions related to the timing of irrigations, desiccant application, and crop harvest.