Rheological characterization of jet-cooked Lesquerella fendleri seed gum and cornstarch solutions

Lesquerella is a potential new seed crop that contains hydroxy fatty acid triglycerides and approximately 15% seed coat gums. The polysaccharide gum of the Lesquerella fendleri seed was isolated and jet-cooked with cornstarch in a series of laboratory experiments to investigate the viscoelastic properties of gum-modified starch solutions. The Lesquerella gum was combined with cornstarch at 1, 5, and 10% levels to produce a jet-cooked and drum dried material with potential application as a thickening or suspension agent. Flow curves were determined for 1% solutions of jet-cooked starch and gum combinations. All materials investigated were biodegradable and exhibited positive thixotropic behavior.     

Lesquerella fendleri response to different sowing dates in northern Mexico

Lesquerella fendleri (Gray) Wats. is a Brassicaceae native to northern Mexico and southern United States. The seeds contain an oil similar to castor oil that may be used for a wide array of industrial products. The U.S. imports 41,000 t of castor oil per year. Thus, Lesquerella oil may be an economic replacement for castor oil. The Mexican growers in the semiarid lands have the potential for cultivating Lesquerella if the crop can be grown in the native regions. The object of this study is to determine the effect of sowing date on seed yield and oil content in Lesquerella grown at Saltillo located in northern Mexico. The plants were sown at three different dates (23 October 2003, 16 December 2003, and 17 March 2004) and harvested in 2004 on 15 May, 24 June, and 27 August, respectively. Irrigation was applied for germination and seedling establishment and to maintain soil moisture. The experimental design was a complete randomized block design with eight replications. Plant morphological variables as well as yield characteristics were measured and related to sowing dates and climatic conditions. The longer period for crop development was due to shorter photoperiod. Plant densities were highest when the crop was sown in December and March, although the densities of three sown dates were within the reported limit for high yield. Seed yield was highest when the crop was sown in December and the oil content increased in the March planting when the mean temperature during seed formation was highest. Infrared spectra of the seeds crude extracts showed different functional groups that varied with climatic conditions.     

Functional properties of protein from Lesquerella fendleri seed and press cake from oil processing

This investigation determined the functional properties of protein in Lesquerella fendleri seed and press cake from oil processing. L. fendleri seeds were heat-treated at 82 °C (180 °F) during 120 min residence time in the seed conditioner, and then screw-pressed to extract the oil. Unprocessed ground, defatted lesquerella seeds and press cakes were analyzed for proximate composition and protein functional properties. Protein from unprocessed lesquerella seed showed the greatest solubility (≥60%) at pH 2 and 10 and was least soluble (25%) at pH 5.5–7. Unprocessed lesquerella protein also had high surface hydrophobicity index (S_o), as well as, excellent foaming capacity and stability, emulsifying properties, and water-holding capacity (WHC) at pH 7. Protein solubility profile of the press cake showed up to 50% reduction in soluble proteins at nearly all pH levels, indicating heat denaturation during cooking and screw-pressing. Foaming capacity of the press cake protein decreased slightly, but foam stability was completely lost. Press cake protein also had markedly reduced values for S_o, emulsifying properties and WHC, further confirming lesquerella protein’s sensitivity to heat treatment.     

Evapotranspiration,yield, and water-use efficiency responses of Lesquerella fendleri at different growth stages

Lesquerella fendleri (Gray) Wats. is a potential new oilseed crop for the arid southwestern United States. Lesquerella seed oil with similar properties as castor oil is being considered as a domestic replacement for the imported castor oil. Development of new crops with low irrigation needs is of high priority. Because the most critical stage of sensitivity to moisture deficits has not been determined in Lesquerella species, the objectives of this study were: (i) to identify the most critical stage or stages for moisture deficit and, (ii) to determine the effect of moisture deficit on yield, yield components, oil and fatty acid composition. Two-year field studies were conducted at the New Mexico State University, Leyendecker Plant Science Research Center. The experimental design was a randomized complete block. The treatments consisted of (a) T1: Continuous favorable soil moisture [irrigated at 50% soil water depletion (SWD)]. (b) T2: Moisture stress (75% SWD) from establishment to initial flowering with no stress from flowering to final harvest (50% SWD). (c) T3: No stress imposed from establishment to initial flowering (50% SWD) followed by stress to final harvest (75% SWD). (d) T4: Moisture stress (75% SWD) from establishment to final harvest. The amount of water applied ranged from 810 to 729 mm for the first year, and 810 to 625 mm for the second year. Seed weight per plant and number of pods per plant were generally higher when water availability was maintained at or above 50% SWD throughout the growing season. Neither seed number per pod nor seed size was influenced by irrigation treatments. Lesquerella was more sensitive to water availability during flowering and seed development as a greater loss in seed yield occurred when irrigation was delayed to 75% SWD during that stage of development. Seed yield and dry matter production from the 2 year field studies were closely related to the seasonal cumulative evapotranspiration. For each millimeter of evapotranspiration, seed yield increased from 1.8 kg ha⁻¹ mm in 1994–1995 to 1.3 kg ha⁻¹ mm for 1995–1996. The dry matter production increased 13.4 kg ha⁻¹ for each mm increase in seasonal evapotranspiration during 1994–1995. This relationship was a second order polynomial with an R² of 0.86 during 1995–1996. The WUE_gr and WUE_dm were highest under the most favorable water availability conditions for growth and seed development. Delaying irrigation to 75% SWD throughout the crop growth period resulted in the lowest oil content. Lesquerolic acid content was not affected by irrigation during both the growing seasons.     

Cardinal temperatures for germination and early growth of two Lesquerella species

Lesquerella (Lesquerella fendleri) is a potential alternative crop that is being studied for commercial oilseed production. Understanding the minimum temperatures for germination and seedling growth is important for determining potential areas for lesquerella production. The objectives of this study were to determine the cardinal temperatures for germination and seedling growth, and to screen ecotypes for germination and growth characteristics. A temperature gradient table arrangement was used to observe seed germination over a range of temperatures, and time to germination and shoot appearance. Times to 5 mm root length and 5 mm shoot length were also measured to assess cardinal temperatures for seedling survival and growth. Two different species were examined, L. fendleri and a species we refer to as ‘L. pallida aff.’ because it differed from typical L. pallida plants in chromosome number and in oil quality. We concluded that both germination and growth of L. pallida aff. occurred fastest at 22 °C, whereas L. fendleri germinated earlier at 18 °C, but grew faster at 22 °C. L. pallida aff. also had lower germination than L. fendleri over the range studied. Non-dormant seeds of improved lines of L. fendleri had better performance at temperatures above 22 °C than did unimproved accessions. Lines of L. fendleri selected for high oil content and salt tolerance had similar temperature requirements for germination except for improved line WCL-LO3, the current line being used in production. This line had optimal temperatures 6 °C higher for germination and growth than the other improved lines. Accessions of L. fendleri collected from elevations above 2000 m performed better at warmer temperatures, whereas those collected from elevations below 2000 m tended to perform better at cooler temperatures. Dormant seeds of L. fendleri germinated more quickly at low temperatures and had lower base (<3 °C) and optimal (22 °C) temperatures than non-dormant seeds (>7 °C and 28 °C, respectively). We speculate that this partial dormancy trait allows populations of L. fendleri to exploit a wider range of temperature conditions in the wild in order to thrive in extreme environments.     

Effects of fungicide seed treatments on germination, population, and yield of maize grown from seed infected with fungal pathogens

Seedborne fungi can reduce survival, growth, and yield of maize (Zea mays L.). Laboratory, field, and growth chamber experiments were conducted to determine the effects of the seed treatment fungicides fludioxonil, mefenoxam, and azoxystrobin on germination, plant population, and grain yield of maize grown from low-quality hybrid seed infected with seedborne fungal pathogens. Study I used seed of four hybrids infected at 0-54% incidence with Fusarium spp., Stenocarpella maydis, Penicillium spp., Rhizopus spp., and/or Aspergillus spp. Study II used three seed lots for each of two hybrids infected at 7-37% incidence with S. maydis. Warm and cold germination for untreated seed varied among hybrids in both studies. Warm germination of the seed lot with the highest incidence of S. maydis in study II treated with azoxystrobin and fludioxonil was significantly greater (+7%) than the nontreated control. Plant population in study I was significantly affected by seed treatment, hybrid, and their interactions. Populations were greater (≥9%) for fludioxonil, fludioxonil + mefenoxam, and fludioxonil + mefenoxam + azoxystrobin treatments compared to controls. In growth chamber experiments with pasteurized soil, emergence (≥5%) and plant dry weight (≥14%) were both greater than controls only with the triple seed treatment. Plant populations in study II for all seed treatments except mefenoxam and azoxystrobin alone were greater (≥4%) than controls. Yield in study I was significantly affected by hybrid and seed treatment. Yield for one hybrid was higher (≥20%) than the control with all seed treatments except fludioxonil, whereas yield with another hybrid was consistently greater (≥26%) only with the triple seed treatment. Yield in study II was significantly affected by hybrid, seed treatment, and their interactions. Yield was greater (≥8%) than the controls for all seed treatments with one hybrid and with all (≥5%) except azoxystrobin for the other hybrid. Highest yields occurred with the triple seed treatment. Results indicate that fludioxonil and azoxystrobin can increase germination, population, and yield of maize grown from seed infected by S. maydis and other fungi.     

Osmotic priming of true potato seed: Effects of seed age

Summary The effects on germination and early seedling growth of presowing true potato seed in water or gibberellic acid (GA) at 1500 ppm and of priming in −1.0, −1.25 and −1.5 MPa solutions of KNO₃+K₃PO₄ were studied using 30, 18, 6 and 3/4 month-old seed. The influence of light during presowing on the effectiveness of treatments was also investigated. Overall, priming in the light at −1.0 MPa was the most, and GA the least successful treatment for enhancing emergence and subsequent seedling growth. Though GA increased final emergence from about 20 to 70% in the most recently harvested lot (3/4 mo), the rate and extent of final germination or emergence in this dormant seed was still much lower than that of the nondormant lots (6–30 mo), especially when the latter were primed. For all lots, dry weight per seedling was 40% lower in dormant than in nondormant seed, and 20% higher when seeds were primed at −1.0 MPa than when GA treated. In conclusion, the use of nondormant seed may be a requirement for both effective priming and sowing of potato crops via true seed.     

Comparison of seed germination and early seedling growth responses to salinity and temperature of the halophyte Chloris virgata and the glycophyte Digitaria sanguinalis

Salinization is an increasing land degradation issue in the Songnen Grassland of northern China. Effects of salinity and temperature on seed germination and seedling growth of Chloris virgata, a promising halophyte, and Digitaria sanguinalis, a widespread glycophyte were examined in six soil solutions (0, 50, 100, 150, 200 and 250 mm NaCl) and four temperatures (15, 20, 25 and 30°C). Germination percentages and rates of both species decreased significantly at higher salinities, but ungerminated seeds can recover germination upon supply of distilled water. Radicle length, seedling height and the total dry weight of both species generally decreased in a concentration‐dependent manner at 20°C and above as the salinity increased. However, at 15°C, the salt‐treated seedlings showed decreases with a similar magnitude for different salinities. Low salinities seem to stimulate germination and seedling growth of C. virgata compared with the control treatment. Both species were more sensitive to salinity during the seedling stage than the germination stage. Digitaria sanguinalis from the saline Songnen Grassland region seems to develop a halophyte‐like adaptive strategy to some extent. However, C. virgata may still dominate most hyperhaline areas due to its higher salt tolerance.     

Enhancing the performance of transplanted coarse rice by seed priming

Raising the rice seedlings in the nursery and its transplantation into the flooded fields is principal method of rice cultivation in the world. Traditional nursery raising method in Pakistan is tedious and produces week seedlings, which reduces the final yield due to high mortality. The potential of seed priming to improve the nursery seedlings and thus the transplanted rice was evaluated in the present study. Seed priming tools employed during the investigation included traditional soaking (pre-germination), hydropriming for 48 h, osmohardening (KCl or CaCl₂) (ψs-1.25 MPa) for 24 h (1 cycle), ascorbate priming (with 10 ppm ascorbate) for 48 h or seed hardening for 24 h. Priming improved nursery seedling vigor and resulted in improved growth, yield and quality of transplanted rice. Osmohardening (KCl) consequently resulted in the best performance, followed by osmohardening (CaCl₂)_, hardening and ascorbate priming. Osmohardening (KCl) produced 4.28 t ha⁻¹ (vs. 3.51 t ha⁻¹ from untreated control) kernel yield, 10.27 t ha⁻¹ (vs. 9.34 t ha⁻¹ from untreated control) straw yield and 29.41% (vs. 27.31% from untreated control) harvest index. The improved yield was attributed to increase in number of fertile tillers.     

紫毛野牡丹种子萌发的研究

观察紫毛野牡丹种子的形态特征并测定其基本参数。结果表明：紫毛野牡丹种子的萌发需要光照条件,全黑暗条件下种子发芽受到限制;低浓度（0-20 mg.L-1）的6-BA可提高紫毛野牡丹种子的发芽率和发芽势,浓度为10 mg.L-1时,效果最为显著。IAA抑制紫毛野牡丹种子的萌发,在一定范围内,发芽率随着IAA浓度的提高而降低。     

Effects of 1,3-dichloropropene plus chloropicrin on weed seed germination

Telone C-35, a commercial formulation of 1,3-dichloropropene (1,3-D) and chloropicrin (CP), is one of the potential replacements to methyl bromide (MB) for soil fumigation. A laboratory dose–response study and two field trials in tomato were conducted to evaluate their weed control efficacy and their effect on tomato yield. Laboratory studies found that the seeds of Digitaria chinensis were the most sensitive to soil fumigation with Telone C-35, followed by Eleusina indica, Portulaca oleracea and Stellaria media with the LC₅₀ values between 3.35 and 11.68 mg kg⁻¹ soil. Field trials revealed that Telone C-35 applied to the field at 327, 243 and 164 L ha⁻¹ could suppress the percentage of germination weed seeds while maintaining high tomato marketable yields, with no significant differences between MB + CP and the higher two Telone C-35 rates. The yield data from both seasons indicated that all Telone C-35 treatments had a positive effect on tomato yield; there was a 32%–62% increase the mean marketable tomato yield. Our results indicated that Telone C-35 was an excellent MB alternative and could provide acceptable weed control efficacy. Based on our results, Telone C-35, in combination with other alternatives to MB, is recommended to achieve integrated pest management.     

激光辐照水对小麦种子萌发影响的研究

利用激光辐照水处理小麦种子,对种子萌发速度与萌发质量进行测定。用不同激光辐照条件作用过的水处理小麦种子,对其萌发情况进行了分析和讨论,着重研究了有利于小麦种子萌发的激光参数条件以及激光辐照水对其的保留效应与累积效应。实验结果表明激光技术在促进种子萌发方面有很好的应用前景。     

干旱胁迫对圆叶决明种子萌发的影响

通过聚乙二醇（PEG-6000）溶液模拟干旱条件,分别对圆叶决明CPI86134与CPI34721种子进行胁迫处理,测定不同胁迫梯度下,发芽率、发芽势、相对发芽势、胚根/胚芽比值等指标的变化情况,据此综合评定两者的抗旱性。结果表明,不同浓度的PEG胁迫环境对圆叶决明种子萌发有显著影响,随着干旱胁迫程度加大,对种子萌发的抑制作用明显增强,活力指数对PEG胁迫的反应更敏感。CPI34721与CPI86134种子萌发受干旱胁迫抑制的程度不同,其中CPI34721较弱,CPI86134相对较强。萌发初期,CPI34721的发芽率、相对发芽率、发芽势、相对发芽势、发芽指数等指标与CPI86134比较都表现出较高的数值。