Growth, photosynthesis and root reserpine concentrations of two Rauvolfia species in response to a light gradient

Growth and secondary metabolites responses to light environment can be useful measurements to determine favourable habitat conditions for the cultivation and conservation of medicinal plants. We analyzed the growth, photosynthesis and root reserpine concentrations in seedlings of Rauvolfia vomitoria Afzel and Rauvolfia verticillatae (Lour.) Baill, two important medicinal plants yielding anti-hypertension alkaloids, at four different light levels (20%, 52%, 75% and 100% of full sunlight) in a shade house. Across all light intensities, seedlings of R. vomitoria grew faster with higher relative growth rate (RGR) than R. verticillatae, attributed to its higher photosynthetic capacities (light-saturated photosynthetic rate, A_max) and leaf area ratio (LAR). Typical shade-sun morphological responses to increasing light levels included decreased specific leaf area and LAR, whereas RGR and A_max was highest at median light levels for both species. R. vomitoria allocated higher leaf mass fraction and fine-root mass fraction, similar coarse root mass fraction, but lower stem biomass fraction than R. verticillatae. For fine roots, R. vomitoria had greater specific root length and small diameter than R. verticillatae, indicating its higher resource (water and nutrition) capture abilities. Both species had higher nitrogen concentration and lower reserpine concentration in fine roots than those of coarse roots. Neither reserpine concentration nor nitrogen was affected by light intensities. The reserpine concentration in coarse roots of R. vomitoria increased, whereas that of R. verticillatae decreased with increasing irradiance. Although not significantly, reserpine concentrations in coarse roots were positively correlated with A_max and RGR for both species across all light intensities. Shade or photosynthesis inhibition apparently did not increase alkaloid synthesis, which contrasted with the carbon/nutrient balance theory of plant defense. These results suggested that R. vomitoria and R. verticillatae could attain high biomass and yield of reserpine in high-light habitats (with max. in 75% sunlight), and intermediate-light habitats (with max. in 25–52% sunlight), respectively.     

Changes in essential oil and fatty acid composition in coriander (Coriandrum sativum L.) leaves under saline conditions

The influence of salinity on essential oil and fatty acid composition of Tunisian coriander (Coriandrum sativum L.) leaves grown in hydroponic culture was investigated. Volatile constituents and fatty acid of leaves were analyzed. The essential oil yield increased significantly up to 18 and 43% with 25 and 50 mM NaCl, respectively and decreased significantly under high salinity. The major volatile compound in leaves was (E)-2-decenal with 52% of total essential oil constituents, followed by decanal, dodecanal, (E)-2-tridecenal and (E)-2-dodecenal. Further, the content of these compounds was affected differently by the treatment level.Salinity decreased significantly the total fatty acid content of the upper and basal leaves. α-Linolenic (C18:3n3) was the main compound of both organs, followed by linoleic (C18:2n6), heptadecenoïc (C17:1n7) and palmitic (C16:0) acids. Raising NaCl concentrations lead to an important decrease in the unsaturated to saturated fatty acid ratio stimulating the formation of more rigid membrane.     

水分胁迫对不同抗旱性燕麦品种光合及产量形成的影响

为了解水分胁迫对不同抗旱性燕麦品种光合和产量的影响,以抗旱性不同的蒙燕1号和坝莜3号为材料,在拔节期和抽穗期采用防雨棚盆栽方式,测定分析了不同水分处理［重度胁迫（30%田间持水量（FWC））、中度胁迫（45%FWC）,适度控水（60%FWC）和正常供水（CK,75%FWC）］下燕麦叶片叶绿素含量、气体交换速率、叶绿素荧光动力学参数、产量及其构成因素的差异。结果表明,两个燕麦品种叶片叶绿素a含量、叶绿素b含量及叶绿素总含量、净光合速率、蒸腾速率、最大荧光、最大光化学效率（F_v/F_m）、实际光化学效率、光化学猝灭系数均随着水分胁迫程度的加剧而下降,初始荧光与非光化学淬灭系数则呈上升趋势,且水分敏感品种坝莜3号的光合受抑制程度显著大于抗旱品种蒙燕1号。燕麦的光合特性和产量受水分胁迫影响的程度整体上表现为拔节期大于抽穗期。中度和重度水分胁迫下坝莜3号的每穗小穗数、千粒重均下降,而每穗秕粒数显著增加,减产13.9%～25.7%。蒙燕1号的产量在适度控水条件下未显著下降,且水分利用效率较高,而在中度和重度水分胁迫下每穗小穗数和穗粒数均显著降低,导致减产9.1%～23.5%,但其 F_v/F_m和叶绿素a/b值较高;在相同水分条件下蒙燕1号的产量显著高于坝莜3号。这说明在水分胁迫下抗旱性强的燕麦品种的光系统Ⅱ的损伤和光抑制较轻,光合同化能力较强,产量损失少。     

Boldo (Peumus boldus) cultivated under different light conditions, soil humidity and plantation density

Boldo (Peumus boldus Mol.) is a medicinal plant native to the central zone of Chile and part of the sclerophyll forest. More than 2000 tons of dried leaves exported annually are wild collected. To develop a cultivation system that supports sustainable production of boldo leaves, we have studied growth and harvest of boldo under different light and soil water conditions. The leaf yield per plant as well as the alkaloid and essential oil content were the same for plants grown under shade and for plants exposed to full sun. The only difference between the shaded and the full sun plants was a higher percentage of stem in the harvested product of shade grown plants. This result would permit the intercropping of boldo in forest plantations without affecting the leaf yield and medicinal quality. The excellent adaptation to dry conditions was confirmed, as the different treatments of soil water led to similar leaf yields and plant heights. Plants submitted to water stress produced fewer but longer shoots and contained less essential oil. None of the treatments except water stress affected the medicinal quality requirements of alkaloid or essential oil concentration in the leaves. Wild collected leaves are inexpensive because of low production costs. To be able to compete with wild supplied leaves in the international market, we have evaluated high density plantings as a way to lower costs of a cultivated product by mechanizing harvest. High planting densities led to loweryielding individuals, but leaf yield per area increased. Plant height and the percentage of leaves in the harvested product was the same for densities of 8- and 16 plants m⁻². The leaves produced by cultivated boldo generally fulfill the requirements described in the European Pharmacopoeia. We conclude that boldo can be successfully cultivated under the described cultivation conditions.     

Growth and yield responses of upland NERICAs to variable water management under field conditions

This study aimed to investigate the possible causes for inconsistent performances of upland New Rice for Africa (NERICA) varieties in uplands and lowlands, while identifying important determinants in grain yield under deficient soil moisture. We compared the growth and yield of NERICA 1 and NERICA 5 to those of Yumenohatamochi, a Japanese upland variety, and Hinohikari, a Japanese lowland variety, subjected to different water management regimes (continually flooded, supplementary irrigation, and non-irrigation). Under conditions of deficient soil moisture, panicle number per square meter, spikelet number per panicle, and 1000-grain weight of NERICAs decreased, whereas the panicle number of the Japanese varieties experienced little change. In contrast, the grain filling ratio was unaffected by water management, irrespective of variety. The primary source of yield reduction under low soil water conditions was a decrease in spikelet number per panicle, and water stress intensity was the primary factor for the degree of this reduction. Variation in the abortion of secondary rachis-branches caused differences between NERICAs in their spikelet number response to soil moisture deficiency. The inconsistency in NERICA performance across uplands vs. lowlands can be partially attributed to variation in yield response to low soil water conditions. Moreover, water stress intensity and the presence of a water gradient along the vertical soil profile may combine to affect the fluctuation in NERICA performance under upland conditions.     

Development and growth of two Lesquerella species grown under different temperatures during the reproductive period

The genus Lesquerella is a promising source of hydroxy fatty acids (HFA). Several species such as Lesquerella fendleri and Lesquerella mendocina are candidate crops for arid and semi-arid cropping systems. Several reports are available on the environmental effects on growth and yield in Lesquerella, but information on the effect of temperature on plant growth and development specifically during the reproductive period in Lesquerella is limited. The objective of this work was to determine the effect of two contrasting thermal regimes after flowering on time to maturity, plant growth and biomass allocation to the different organs in L. fendleri and L. mendocina. A greenhouse experiment was conducted with plants grown at a range of 11–23 °C during the vegetative phase. After this stage, 50% of the plants of each species remained under the same temperature regime until maturity, whereas the other 50% was transferred to another module subjected to a range of 17–31 °C until maturity. The duration of the reproductive phase was reduced by 23 days in plants of both species in the 17–31 °C treatment compared to those at 11–23 °C, although no differences were observed when the length of the reproductive phase was measured in thermal-time units. Total plant biomass for both species was 20% greater in the 11–23 °C treatment. In L. fendleri, this increment occurred due to more vegetative shoot biomass, whereas in L. mendocina it was associated with greater reproductive and root biomass. No changes in biomass allocation were produced by temperature in L. fendleri, while in L. mendocina the lower temperature regime increased allocation to the reproductive organs, at the expense of a lower allocation to vegetative shoot. These results could be used to predict the specific temperature effects after flowering on yield under field conditions, and suggest that L. mendocina might be a promising perennial alternative for cooler sites.     

生长温度对烤烟生物碱含量及烟碱代谢相关酶基因表达的影响

以云烟87为材料,采用人工气候室模拟云南江川、贵州遵义和河南襄县的气温条件,分别在烟草移栽-团棵、团棵-现蕾及成熟期进行不同温度处理,研究不同生长温度对烟碱、新烟碱、降烟碱和假木贼碱含量以及烟碱代谢关键酶基因表达的影响。结果表明:在3个不同生育期中,较低的生长温度均促进了烟碱的生物合成及其在根系中的积累。在移栽-团棵期,低温处理下根系中的烟碱含量升高至0 d时的1.54倍,而同时期叶片中的烟碱含量显著低于根系;进入团棵-现蕾期以及成熟期后,较高的生长温度则更有利于叶片中烟碱的积累,其烟碱含量较0 d时高约1.80~4.38倍;新烟碱、降烟碱和假木贼碱的含量变化趋势与烟碱基本相似。总体而言,在不同生育期,烟碱的合成和器官水平上的分布不同程度地受到生长温度的影响,成熟期温度对烟碱量的影响最大,具有相对较高生长温度条件的河南襄县更有利于叶片中烟碱的积累。本研究结果揭示了温度调节烟草生物碱含量及烟碱代谢的作用基础,在一定程度上解释了3个地区烟叶香型风格存在差异的原因。     

3种营养液对红掌生长、生理及开花品质的影响

以切花品种‘热情’和盆花品种‘大哥大’为材料,研究了不同配方营养液及浓度对红掌生长的影响。结果表明,1.0倍浓度的配方Q可较全面地提高2个品种红掌的叶面积、株高、花葶长度、佛焰苞面积,使佛焰苞颜色鲜红,显著提升可溶性糖含量;1.3倍浓度的配方Q对佛焰苞观赏品质有显著改善,可溶性蛋白含量高于其他处理。     

继代培养对玉米大斑病菌生长、发育和致病性的影响

经连续单孢分离和培养,获得玉米大斑病菌(Setosphaeria turcica)的22次继代培养菌株.前13代菌株没有明显的生长和发育变化,从第14代开始,继代培养对病菌的生长和发育存在显著影响.随继代次数增加,菌丝生长速度变慢,产孢量下降,分生孢子变小,致病性显著降低,表现出明显退化现象.随着继代培养,菌丝呈变粗趋势.     

Water deficit effects on caraway (Carum carvi L.) growth, essential oil and fatty acid composition

The Mediterranean region suffers of drought which affects plant behaviour regarding biochemical responses. Accordingly, the effects of water deficit on growth, essential oil and fatty acid composition of caraway (Carum carvi L.) seeds were investigated. Plants were treated with different levels of water deficit: control, moderate water deficit and severe water deficit. Plant growth (height, fresh and dry matter weight) was significantly reduced by severe water deficit. This last caused also important reductions of the seed yield and yield components. Drought decreased significantly seed total fatty acid contents and particularly the petroselinic ones whose proportions decreased significantly by 12.17 and 18.47%, in comparison with the control, under moderate water deficit and severe water deficit, respectively. Besides, moderate water deficit increased the essential oil yield (expressed as g/100 g on the basis of dry matter weight). The main essential oil constituents were carvone and limonene which showed an increasing of their contents under water deficit levels. Thus, water deficit induced a significant reduction in growth parameters and fatty acid content, and an increase in the essential oil compounds. These bioactive compounds have been required in many industrial products.     

芽胞杆菌对玉米幼苗生长及土壤酶活性和养分含量的影响

以解淀粉芽胞杆菌NECC10723(Bacillus amyloliquefaciens NECC10723,Bam723)和阿耶波多氏芽胞杆菌NECC10295(Bacillus aryabhattai NECC10295,Bar295)为试验材料,通过盆栽试验,探究接种不同芽胞杆菌对于玉米幼苗的生长指标、土壤酶活性和土壤养分含量的影响。结果表明,盐碱胁迫下接种不同芽胞杆菌均对玉米幼苗起到不同程度的促生作用,Bam723和Bar295均在1×10⁷cfu/mL浓度下促生效果最为显著,提高盐碱胁迫下玉米幼苗的株高、茎粗、地上部及地下部干重和根冠比。土壤中施加Bam723可显著提升盐碱胁迫下玉米幼苗种植土壤中的酶活和土壤养分含量,与对照处理相比,土壤中脲酶、碱性磷酸酶、蔗糖酶活性分别提高19.31%、31.77%和45.78%;土壤全氮、速效磷、速效钾含量分别提高137.54%、295.49%和3.19%,增加幅度均大于Bar295处理。     

Leaf gas exchange, chloroplastic pigments and dry matter accumulation in castor bean (Ricinus communis L) seedlings subjected to salt stress conditions

Brazilian castor bean (Ricinus communis L) crops have expanded towards semiarid lands, in which soil salinity is an important factor limiting plant development. In order to evaluate the effects of salt stress on leaf gas exchange, pigments, and dry matter accumulation of seedlings, seeds of castor bean var. BRS Nordestina were planted in 15-L pots filled with 13 kg of soil (control) or with soil plus 2 g NaCl kg⁻¹ soil corresponding to 30 mM NaCl (salt treatment). Seedlings were grown under greenhouse conditions and the effects of salinity were assessed by measuring physiological parameters at 38 and 59 days after germination. Salt treatment induced decreases in leaf water potential at pre-dawn (ψ_pd, 42%), stomatal conductance to water vapor (g_s, 36%), and net carbon assimilation rate (A, 24%) only at 38 days after germination. At the same time, the values for transpiration rate were unchanged and the hydraulic conductance was increased (34%). After 59 days under hypersalinity, leaf ψ_pd increased to −0.44 MPa, although g_s, A, transpiration rate, and hydraulic conductance were not different between treatments. Salt stress effects on chlorophyll a, chlorophyll b and chlorophyll a + b contents were evident only on experimental day 59. The dry matter accumulation of leaves, roots and stems, as well as the total dry matter, and the root to above ground ratio increased with plant growth in both treatments, however, these parameters were lowered in salt-stressed seedlings. In short, all physiological variables were more drastically affected after 38 days under high salinity, and despite acclimatization of A after 59 days exposure to salt, no recovery of the dry matter accumulation was observed in the seedlings, suggesting that this species does not tolerate salt stress at its initial growth stages.     

外源水杨酸对Hg~(2+)胁迫下小麦幼苗生长及生理的影响

为了解水杨酸(SA)对Hg2+胁迫小麦幼苗生长的缓解作用,以小麦品种豫麦58号为材料,采用室内水培法分析了在Hg2+胁迫下小麦幼苗经不同浓度SA处理后的生长及生理变化。结果表明,外施SA能显著提高Hg2+胁迫下小麦幼苗的根长、株高、单株鲜重,叶片叶绿素、脯氨酸和可溶性蛋白含量,以及抗氧化酶活性和根系活力(P0.05),极显著降低丙二醛含量与超氧阴离子产生速率(P0.01)。说明外施SA可通过提高小麦幼苗可溶性蛋白和脯氨酸含量及抗氧化酶活性来维持细胞膜的稳定性,降低膜脂过氧化伤害程度,从而缓解了Hg2+胁迫对幼苗生长的抑制作用,其中以40mg·L-1 SA缓解效果最好。     

Growth, yield and mineral content of Miscanthus × giganteus grown as a biofuel for 14 successive harvests

Miscanthus × giganteus, a perennial rhizomatous grass commercially used as a biofuel crop was grown in a field experiment on a silty clay loam soil for 14 years. There were 3 rates of fertilizer nitrogen (N), none (control), 60 kg N ha⁻¹ yr⁻¹ and 120 kg N ha⁻¹ yr⁻¹ as cumulative applications. The crop was harvested in winter and dry matter yield measured. N did not influence yield. Yield, which increased for the first 6 years, decreased in years 7 and 8, but then increased again and was highest in the 10th year averaging 17.7 t ha⁻¹ across all treatments. Differences in total production over the14 years were only 5% between the highest and lowest yielding treatments and averaged 178.9 t ha⁻¹ equivalent to 12.8 t ha⁻¹ yr⁻¹. In the first 10 harvests, 92% of dry matter was stem. Although the study showed N fertilizer was not required, it is considered that an application of 7 kg P ha⁻¹ yr⁻¹ and 100 kg K ha⁻¹ yr⁻¹ would avoid soil reserve depletion. Pesticides were not required every year and the crop can be considered as low input with a high level of sustainability for at least 14 years.     

Effects of partial root-zone drying on yield,tuber size and water use efficiency in potato under field conditions

Water resources are limited for irrigation worldwide; therefore, there is a need for water-saving irrigation practices to be explored. Partial root-zone drying (PRD) is a new water-saving irrigation strategy being tested in many crop species. Experiments were conducted in potato (Solanum tuberosum L. cv. Folva) under open field conditions in 2004 and under a mobile rainout shelter in 2005. Two subsurface irrigation treatments were studied: full irrigation (FI) receiving 100% of evaporative demands, 50.1 and 201 mm of irrigation water in the 2 years, to keep it close to field capacity; and PRD, which received 21.7 and 140 mm of irrigation in 2004 and 2005 respectively. Due to rain in 2004, the PRD treatment was imposed over a short period only during the late tuber filling and maturing stages. In 2005, the PRD treatment was imposed during the whole period of tuber filling and tuber maturation. The PRD treatment was shifted from one side to the other side of potato plants every 5–10 days. Especially in 2005 it was apparent that stomatal conductance was generally lower in the PRD than in the FI plants, whereas leaf water potential tended to be lower in only a few instances. During the treatment period, plants were harvested five times, and no significant difference was found between the treatments in leaf area index, top dry mass and tuber yield. At final harvest, tubers were graded based on size into four classes C₁–C₄, of which the yield of the important marketable class (C₂) was significantly higher (20%) in the PRD than in the FI treatment. Compared with FI, the PRD treatment saved 30% of irrigation water while maintaining tuber yield, leading to a 61% increase of irrigation water use efficiency. The limited data of 2004 support these results. In summary, PRD is a promising water-saving irrigation strategy for potato production in areas with limited water resources.     

Influence of environment on growing period and yield, protein, oil and α-linolenic content of three chia (Salvia hispanica L.) selections

Chia (Salvia hispanica L.) is an annual summer herb, and a member of the Labiatae family. Three selections, named Tzotzol, Iztac 1, and Tliltic, were planted at different elevations in three Inter-Andean valleys of Ecuador (Patate—2042 m, Guayllabamba—2200 m and Salinas—1621 m) to assess performance and seed quality. Length of growing period was influenced by location, with Tzotzol and Iztac 1 increasing with elevation. Iztac 1 had the highest seed yield at all three locations, with the difference between Iztac1 and Tzotzol being significant (P < 0.05). Similar protein contents were found among selections, within a site, except for Patate where Tliltic had a higher content. Seed at the Salinas site contained significantly (P < 0.05) higher α-linolenic and lower linoleic and oleic fatty acid contents than seed produced at the other two sites. In general seed yield, protein content, and fatty acid composition of the three selections were similar, and in some cases higher, than those reported for other ecosystems in which chia has been grown.     

Impact of the catalytic activity of iodine on the granule morphology, crystalline structure, thermal properties and water solubility of acetylated corn (Zea mays) starch synthesized under microwave assistance

By activating corn starch with acetic acid and using acetic anhydride as an esterifying agent, starch acetates with increasing degrees of substitution were obtained using microwave assistance when the amount of iodine varied from 0.5 to 1.75 mmol. The study of Fourier Transform Infrared (FT-IR) spectra, X-ray diffraction pattern, thermal properties, granule morphology, water absorption and solubility, revealed important changes on the physical properties of the obtained products related to the increase of the iodine content. As shown by the scanning electron microscope (SEM), a specific structure on the granule surface was discerned for each amount of iodine. By its exo-corrosive action on starch, iodine indirectly induced loss of crystallinity, decrease of the glass transition and melting temperatures, and a progressive reduction in the water absorption and water solubility index of the modified products. Starch esters with better hydrophobicity and good processability for bio-based material applications were synthesized. Alternatively, the variation in the concentration of the iodine could also be of interest in special purposes, in which starch granules with controlled surface porosity are needed.