Effect of irradiation intensity on cell growth and kalata B1 accumulation in <Emphasis Type="Italic">Oldenlandia affinis</Emphasis> cultures

Light irradiation had remarkable effects on callus growth of Oldenlandia affinis with an optimum intensity of 35 μmol m⁻² s⁻¹. Biosynthesis of kalata B1, the main cyclic peptide in O. affinis, was induced and triggered with rising irradiation intensities. The highest concentration of kalata B1, 0.49 mg g⁻¹ DW characterised by the maximum productivity of 3.88 μg per litre and day was analysed at 120 μmol m⁻² s⁻¹, although callus growth was repressed. The light saturation point was established to be 35 μmol m⁻² s⁻¹, where kalata B1 productivity was in a similar order (3.41 μg per day) due to the higher growth index. O. affinis suspension cultures were shown to accumulate comparable specific kalata B1 concentrations in a delayed growth associated production pattern. These were dependent on irradiation intensity (0.16 mg g⁻¹ at 2 μmol m⁻² s⁻¹; 0.28 mg g⁻¹ at 35 μmol m⁻² s⁻¹). The batch cultivation process resulted in a maximum productivity of 27.30 μg per litre and day with culture doubling times of 1.16 d⁻¹. Submers operation represented a 8-fold product enhancement compared to callus cultivation.     

Mycorrhizal dependence of four crops in a P-sorbing soil

The effect of methyl bromide and P fertilization on the growth of four agricultural crops in a P-sorbing soil was studied. Harvestable yields and P tissue content were significantly lower for celery (Apium graveolens L.), onion (Allium cepa L.) and pepper (Capsicum annuum L.) following fumigation. P fertilization up to 330 kg P ha⁻¹ as superphosphate could not reverse this effect. The highest P fertilizer treatment had 25.4 μg g⁻¹ bicarbonate-extractable P and 0.26 μg g⁻¹ water extractable P. This P level produced acceptable commercial yields when vesicular arbuscular mycorrhizae (VAM) were present (non-fumigated) and indicate the importance of the VAM association for these crops. In contrast, melon (Cucumis melo L.) growth was slightly greater following soil fumigation at all P fertilization rates. These findings indicate that crop VAM dependence and efficacy of VAM biotypes must be considered as essential components for P fertilization recommendations on fumigated P-sorbing soils. Formerly Gilat, now University of Kent, Kent, UK     

Estimates of biomass and primary productivity in a high-altitude maple forest of the west central Himalayas

The paper describes the biomass and productivity of maple (Acer cappadocicum) forest occurring at an altitude of 2,750 m in the west central Himalayas. Total vegetation biomass was 308.3 t ha⁻¹, of which the tree layer contributed the most, followed by herbs and shrubs. The seasonal forest-floor litter mass varied between 5.4 t ha⁻¹ (in rainy season) and 6.6 t ha⁻¹ (in winter season). The annual litter fall was 6.2 t ha⁻¹, of which leaf litter contributed the largest part (59% of the total litter fall). Net primary productivity of total vegetation was 19.5 t ha⁻¹ year⁻¹. The production efficiency of leaves (net primary productivity/leaf mass) was markedly higher (2.9 g g⁻¹ foliage mass year⁻¹) than those of the low-altitude forests of the region.     

Drought,warming and soil fertilization effects on leaf volatile terpene concentrations in <Emphasis Type="Italic">Pinus halepensis</Emphasis> and <Emphasis Type="Italic">Quercus ilex</Emphasis>

The changes in foliar concentrations of volatile terpenes in response to water stress, fertilization and temperature were analyzed in Pinus halepensis and Quercus ilex. The most abundant terpenes found in both species were α-pinene and Δ³-carene. β-Pinene and myrcene were also abundant in both species. P. halepensis concentrations were much greater than those of Q. ilex in agreement with the lack of storage in the latter species (15205.60 ± 1140.04 vs. 0.54 ± 0.08 μg g⁻¹ [d.m.]). The drought treatment (reduction to 1/3 of full watering) significantly increased the total terpene concentrations in both species (54% in P. halepensis and 119% in Q. ilex). The fertilization treatment (addition of either 250 kg N ha⁻¹ or 250 kg P ha⁻¹ or both) had no significant effects on terpene foliar concentrations. The terpene concentrations increased from 0.25 μg g⁻¹ [d.m.] at 30°C to 0.70 μg g⁻¹ [d.m.] at 40°C in Q. ilex (the non-storing species) and from 2,240 μg g⁻¹ [d.m.] at 30°C to 15,621 μg g⁻¹ [d.m.] at 40°C in P. halepensis (the storing species). Both species presented negative relationship between terpene concentrations and relative water contents (RWC). The results of this study show that higher terpene concentrations can be expected in the warmer and drier conditions predicted for the next decades in the Mediterranean region.     

Nitrogen uptake in a Norway spruce stand following ammonium sulphate application,fertigation, irrigation,drought and nitrogen-free-fertilisation

The above-ground accumulation of N,N uptake and litter quality resulting from improved or deteriorated availability of water and nutrients in a 25 year old Norway spruce stand in SW Sweden (as part of the Skogaby project) is presented. Treatment include irrigation; artificial drought; ammonium sulphate addition; N-free-fertilisation and irrigation with liquid fertilisers including a complete set of nutrients according to the Ingested principle (fertigation). At start of the experiment the stand contained 86.5 t dry mass and 352 kg N ha⁻¹. The following three years the annual N uptake in untreated trees was 32 kg N ha⁻¹ to be compared with the annual N throughfall of 17 kg ha⁻¹. Simultaneously, the treatment with ammonium sulphate and liquid fertilisation resulted in 48 and 56 kg ha⁻¹ y⁻¹, respectively, in treatment specific N-uptake following an application of 100 kg N ha⁻¹ y⁻¹. Addition of a N-free fertiliser resulted in improved N-uptake by 19 kg N ha⁻¹ y⁻¹ and irrigation by 10 kg N ha⁻¹ y⁻¹, compared to control. A linear relation between total above-ground dry mass production and N-uptake was found for trees growing with similar water availability. Dry mass production increased with increased water availability given the same N-uptake. It is concluded that the studied stand this far is not N saturated', as N fertilisation resulted in both increased N uptake and increased growth. Addition of a N-free-fertiliser resulted in increased uptake of N compared to the control, indicating an increased mineralisation rate or uptake capacity of the root system. The linear relation between N uptake and biomass production shows that at this study site N is a highly limiting factor for growth.     

Inhibition of mycorrhizal symbiosis in Leucaena leucocephala by chlorothalonil

The effect of the fungicide, chlorothalonil, on vesicular-arbuscular mycorrhizal (VAM) symbiosis was studied in a greenhouse using Leucaena leucocephala as test plant. Chlorothalonil was applied to soil at 0, 50, 100 and 200 μg g⁻¹. The initial soil solution P levels were 0.003 μg mL⁻¹ (sub-optimal) and 0.026 μg mL⁻¹ (optimal). After 4 weeks, the sub-optimal P level was raised to 0.6 μg mL⁻¹ (high). The soil was either uninoculated or inoculated with the VAM fungus, Glomus aggregatum. The fungicide reduced mycorrhizal colonization of roots, development of mycorrhizal effectiveness, shoot P concentration and uptake and dry matter yields at all concentrations tested, although the highest inhibitory effect was noted as the concentration of the fungicide was increased from 50 to 100 μg g⁻¹. Phosphorus applied after four weeks tended to partially offset the deleterious effects of chlorothalonil in plants grown in the inoculated and uninoculated soil which suggests that the fungicide was interfering with plant P uptake. The results suggest that the use of chlorothalonil should be restricted to levels below 50 μg g⁻¹ if the benefits of mycorrhizal symbiosis are to be expected. Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464. Contribution from Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3464.     

The requirement of zinc for improvement of crop yield and mineral nutrition in the maize–mungbean–rice system

A study was made over 3 years to find out an optimum rate of Zn application for the maize–mungbean–rice cropping system in a calcareous soil of Bangladesh. Zinc application was made at 0, 2 and 4 kg ha⁻¹ for maize (cv. Pacific 984, Thai hybrid) and at 0, 1 and 2 kg ha⁻¹ for rice (cv. BRRI dhan33), with no Zn application for mungbean (cv. BARI mung5). Effect of Zn was evaluated in terms of yield and mineral nutrients contents (N, P, S and Zn). All the three crops responded significantly to Zn application. The optimum rate of Zn for the maize–mungbean–rice cropping system was found to be 4–0–2 kg ha⁻¹ for the first year and 2–0–2 kg ha⁻¹ for subsequent years particularly when mungbean residue was removed, and such rates for mungbean residue incorporation being 4–0–1 and 2–0–1 kg ha⁻¹, respectively. For all crops, the Zn and N concentrations of grain were significantly increased with Zn application. For the case of grain-S, the concentration was significantly increased for maize and mungbean, but it remained unchanged for rice. The grain-P concentration on the other hand tended to decrease with Zn application. For maize, the grain-Zn concentration increased to 27.0 μg g⁻¹ due to 2 kg Zn ha⁻¹ treatment from 16.5 μg g⁻¹ for Zn control and at higher Zn rate (4 kg Zn ha⁻¹) the increment was very minimum. Another field experiment was performed over 3 years on the same soil to screen out maize varieties for Zn efficiency. Of the eight varieties tested, the BARI maize 6 and BARI hybrid maize 3 were found Zn in-responsive (Zn efficient) and the others Zn responsive (Zn-inefficient).     

Effective biotic elicitation of <Emphasis Type="Italic">Ruta graveolens</Emphasis> L. shoot cultures by lysates from <Emphasis Type="Italic">Pectobacterium atrosepticum</Emphasis> and <Emphasis Type="Italic">Bacillus</Emphasis> sp.

Growth of Ruta graveolens shoots was induced when Bacillus sp. cell lysates were added to the culture medium. Elicitation of coumarin by this lysate was also very effective; the concentrations of isopimpinelin, xanthotoxin and bergapten increased to 610, 2120 and 1460 μg g⁻¹ dry wt, respectively. It also had a significant effect on the production of psoralen and rutamarin (680 and 380 μg g⁻¹ dry wt) and induced the biosynthesis of chalepin, which was not detected in the control sample, up to 47 μg g⁻¹ dry wt With lysates of the Pectobacterium atrosepticum, their effect on growth was not so significant and had no effect on the induction of coumarin accumulation. But elicitation with this lysate was much more effective for inducing the production of furoquinolone alkaloids; the concentrations of γ-fagarine, skimmianine, dictamnine and kokusaginine rose to 99, 680, 172 and 480 μg g⁻¹ dry wt, respectively.     

Characterization of natural variation for zinc, iron and manganese accumulation and zinc exposure response in Brassica rapa L.

Brassica rapa L. is an important vegetable crop in eastern Asia. The objective of this study was to investigate the genetic variation in leaf Zn, Fe and Mn accumulation, Zn toxicity tolerance and Zn efficiency in B. rapa. In total 188 accessions were screened for their Zn-related characteristics in hydroponic culture. In experiment 1, mineral assays on 111 accessions grown under sufficient Zn supply (2 μM ZnSO₄) revealed a variation range of 23.2–155.9 μg g⁻¹ dry weight (d. wt.) for Zn, 60.3–350.1 μg g⁻¹ d. wt. for Fe and 20.9–53.3 μg g⁻¹ d. wt. for the Mn concentration in shoot. The investigation of tolerance to excessive Zn (800 μM ZnSO₄) on 158 accessions, by using visual toxicity symptom parameters (TSPs), identified different levels of tolerance in B. rapa. In experiment 2, a selected sub-set of accessions from experiment 1 was characterized in more detail for their mineral accumulation and tolerance to excessive Zn supply (100 μM and 300 μM ZnSO₄). In this experiment Zn tolerance (ZT) determined by relative root or shoot dry biomass varied about 2-fold. The same six accessions were also examined for Zn efficiency, determined as relative growth under 0 μM ZnSO₄ compared to 2 μM ZnSO₄. Zn efficiency varied 1.8-fold based on shoot dry biomass and 2.6-fold variation based on root dry biomass. Zn accumulation was strongly correlated with Mn and Fe accumulation both under sufficient and deficient Zn supply. In conclusion, there is substantial variation for Zn accumulation, Zn toxicity tolerance and Zn efficiency in Brassica rapa L., which would allow selective breeding for these traits.     

Effects of temperature and ammonium on growth,pigment production and nitrogen uptake by four species of <Emphasis Type="BoldItalic">Porphyra</Emphasis> (Bangiales,Rhodophyta) native to the New England coast

Porphyra is one of the world’s most valued maricultured seaweeds and has been cultivated for several hundred years in Asia. The objective of this study was to produce critical information as a guide for the selection of an appropriate Porphyra species from coastal New England for the development of a land-based aquaculture system. Four Northwest Atlantic Porphyra species: P. leucosticta, P. amplissima, P. linearis and P. umbilicalis, were cultivated for 1 and 2 weeks at saturated light intensities (100–150 μmol photons m⁻²s⁻¹) and six combinations of ammonium (25 and 250 μmoles L⁻¹) and temperature (10, 15 and 20°C). Specific growth rate (SGR) increased with decreasing temperature in P. leucosticta, P. linearis and P. umbilicalis and increased with increasing temperature in P. amplissima. The SGR of all species was greater at the higher ammonium concentration. Porphyra linearis had the highest SGR, increasing in biomass by approximately 16% day⁻¹. Phycoerythrin (PE) content was higher at 10°C and 250 μmoles L⁻¹ in all species except P. amplissima. The PE content, measured as fresh weight (FW), of P. linearis (29 mg g⁻¹ FW⁻¹) and P. umbilicalis (26 mg g⁻¹ FW⁻¹) was significantly higher than the other two species. Tissue nitrogen content of all species measured in dry weight was on average 1.45% higher at 250 μmoles L⁻¹ than at 25 μmoles L⁻¹ ammonium concentration. Porphyra umbilicalis had the highest tissue nitrogen contents (6.76%) at 10°C and 250 μmoles L⁻¹ ammonium. Based on these results, P. linearis and P. umbilicalis should be considered as potential candidates for bioremediation with finfish and shellfish mariculture.     

Guggulsterone production in cell suspension cultures of the guggul tree, <Emphasis Type="Italic">Commiphora wightii</Emphasis>, grown in shake-flasks and bioreactors

Cell suspension cultures of Commiphora wightii, grown in modified MS medium containing 2,4-dichlorophenoxyacetic acid (0.5 mg l⁻¹) and kinetin (0.25 mg l⁻¹), produced ∼5 μg guggulsterone g⁻¹ dry wt. In a 2 l stirred tank bioreactor, the biomass was 5.5 g l⁻¹ and total guggulsterone was 36 μg l⁻¹.     

Root growth,macro-nutrient uptake dynamics and soil fertility requirements of a high-yielding winter oilseed rape crop

Shoot growth, root growth and macro-nutrient uptake by a high-yielding (5t/ha grain) winter oilseed rape crop have been measured. Maximum rooting density in the top 20cm of soil was 9.4 cm cm⁻³ and roots reached a depth of at least 1.8 m. Maximum nutrient uptakes were 364 kg ha⁻¹ for N, 43 kg ha⁻¹ for P, 308 kg ha⁻¹ for K, 287 kg ha⁻¹ for Ca and 16 kg ha⁻¹ for Mg. A 30-day drought coincided with the flowering period and root and shoot growth, as well as nutrient uptake rates, were reduced. Nutrient concentrations in the soil solution necessary to sustain the nutrient fluxes into the root system by diffusive supply have been calculated. Peak values were in the range 10 μM for P to 87 μM for N, lower than the observed concentrations, and it was concluded that nutrient transport to roots was not a limitation to uptake by this rape crop.     

The response ofAzolla pinnata R. Brown to the split application of phosphorus and the transfer of assimilated phosphorus to flooded rice plants

A field experiment was conducted at the Bangladesh Rice Research Institute, Joydebpur, Dhaka during the late wet season. Basal application of P at both 5 and 10 kg ha⁻¹ significantly increased total biomass production and nitrogen fixation byAzolla pinnata R. Brown (local strain). Addition of both 5 and 10 kg P ha⁻¹ in equal splits at inoculation and at six day intervals thereafter during growth periods of 12, 24 and 36 days increased biomass production and nitrogen fixation by Azolla over that attained with the basal application. Biomass and nitrogen fixation using a split application of 5 kg P ha⁻¹ exceeded that attained with basal application of 10 kg P ha⁻¹ and split application of 10 kg P ha⁻¹ resulted in 0.58, 11.2, and 18.3 t ha⁻¹ more biomass, and 0.47, 18.9, and 18.3 more kg fixed N ha⁻¹ at 12, 24 and 36 days, respectively, than the same amount applied as a basal application. Analyses indicated that the critical level of dry weight P in Azolla for sustained growth was in the range of 0.15–0.17%. Compared with the control, where no P was added, and additional 30 and 36 kg N ha⁻¹ were fixed after 24 and 36 days, respectively, when P was provided at 10 kg ha⁻¹ using a split application. A separate field study showed that flooded rice plants received P from incorporated Azolla with about 28% of the P present in the supplied Azolla being incorporated into the rice plants.     

The vitamin content of microalgae used in aquaculture

The vitamin content in four Australian microalgae, a Nannochloropsis-like sp., Pavlova pinguis, Stichococcus sp. and Tetraselmis sp., were examined. These were grown under a 12:12 h light:dark regimen (100 μmol photon m⁻²s⁻¹) and harvested during late-logarithmic phase. Typically, the content showed a two- to three fold range between the species. When expressed on a dry weight basis, the content of ascorbate ranged from 1.3 to 3.0 mg g⁻¹, β-carotene from 0.37 to 1.05 mg g⁻¹, α-tocopherol from 0.07 to 0.29 mg g⁻¹, thiamine from 29 to 109 μg g⁻¹, riboflavin from 25 to 50 μg g⁻¹, total folates from 17 to 24 μg g⁻¹, pyridoxine from 3.6 to 17 μg g⁻¹, cobalamin from 1.70 to 1.95 μg g⁻¹ and biotin from 1.1 to 1.9 μg g⁻¹. Retinol was detected only in Tetraselmis sp. (2.2 μg g⁻¹); any vitamins D₂ or D₃ were below the detection limit (≤0.45 μg g⁻¹). Nannochloropsis sp. was also grown under a 24:0 h light:dark light cycle and harvested at stationary phase. The content of most vitamins in Nannochloropsis sp. cultures differed significantly, and the degree of variation was similar to that observed between the four species grown under 12:12 h light:dark regimen (100 μmol photon m⁻²s⁻¹) and harvested during late-logarithmic phase. Thiamine content was also examined in six non-Australian strains commonly used in aquaculture, Chaetoceros muelleri, Thalassiosira pseudonana, Nannochloris atomus, Nannochloropsis oculata, Isochrysis sp. (T.ISO) and Pavlova lutheri. Values (average 61 μg g⁻¹; range 40 to 82) were similar to those in the Australian strains (average 61 μg g⁻¹; range 29 to 109) and increased during stationary phase (average 94 μg g⁻¹; 38 to 131). Comparison of the data with the known nutritional requirements for marine fish species and prawns suggests that the microalgae should provide excess or adequate levels of the vitamins for aquaculture food chains. The data may be used to guide the content of vitamins included in micro-diets developed as replacements for live diets. This revised version was published online in July 2006 with corrections to the Cover Date.     

Exogenously-supplied trehalose protects thylakoid membranes of winter wheat from heat-induced damage

The effects of trehalose pretreatment on thylakoid membranes of winter wheat were investigated under heat stress. Under normal growth conditions, the winter wheat synthesized 502 μg g⁻¹(f.m.) trehalose, which increased to 1250 μg g⁻¹(f.m.) under heat stress and to 1658 μg g⁻¹(f.m.) in trehalose-pretreated seedlings. Under heat stress, proteins in the thylakoid membranes and the photosynthetic capacity were protected by trehalose pretreatment. Moreover, the electrolyte leakage, contents of malondialdehyde, superoxide anion and hydrogen peroxide, and lipoxygenase activity in trehalose-pretreated seedlings were lower than in the non-pretreated plants.     

Critical Levels of Selenium in Different Crops Grown in an Alkaline Silty Loam Soil Treated with Selenite-Se

Critical levels of selenium in raya (Brassica juncea Czern L.), maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging from 1 to 25 μg g⁻¹ soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g⁻¹ soil in raya and maize; 4 μg Se g⁻¹ soil in wheat and 10 μg Se g⁻¹ soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to be 104.8 μg g⁻¹ in raya, 76.9 μg g⁻¹ in maize, 41.5 μg g⁻¹ in rice and 18.9 μg g⁻¹ in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry matter yield of raya as well as rice (r = −0.99, P ≤ 0.01), wheat (r = −0.97, P ≤ 0.01) and maize ((r = −0.96, P ≤ 0.01). A synergistic relationship was observed between S and Se content of raya (r = 0.96, P ≤ 0.01), wheat (r = 0.89, P ≤ 0.01), rice (r = 0.85, P ≤ 0.01) and maize (r = 0.84, P ≤ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. > 5 mg Se kg⁻¹) when the soil was treated with more than 1.5 μg Se g⁻¹. In case of wheat, application of Se more than 3 μg g⁻¹ soil resulted in production of toxic plants.     

Effects of phosphorus and iron fertilizers on the growth of two soybean varieties at two soil temperatures

The influence of FeEDDHA (0, 0.2 and 2 μg Fe g⁻¹ soil) and NaH₂PO₄·H₂O (0 and 120 μg Pg⁻¹ soil) on the growth of two Fe-ineffective soybean (Glycine max L. Merr.) varieties (anoka and T203) on a calcareous soil at two soil temperatures (16 and 24°C) was compared under greenhouse conditions. The two soybean varieties differed in the following respects: (a) T203 accumulated smaller concentrations of Fe in washed tops than Anoka under comparable conditions; (b) T203 was more susceptible to Fe deficiency and its accentuation by high levels of fertilizer P than Anoka; (c) T203 accumulated lower quantities of Mn in tops than Anoka under comparable conditions; (d) T203, but not Anoka, developed Mn deficiency symptoms when treated with P and 2 μg Fe g⁻¹ at 16°C. Fe deficiency was more severe in both varieties at the higher soil temperature due apparently to: (a) greater plant concentration of P in tops at 24°C; and/or (b) an increased rate of plant growth and greater dilution of Fe in young tissue at 24°C. Foliar P concentration was increased much more than foliar Fe concentration by an increase in soil temperature. Severely Fe deficient T203 plants grown without FeEDDHA at 24°C accumulated less foliar Mn than their FeEDDHA counterparts. Comparisons of Fe effectiveness of various soybean cultivars based on relative responses to FeEDDHA can be influenced by differential effects on Mn nutrition.     

Aboveground biomass and litterfall ofPinus pumila scrubs growing on the Kiso mountain range in central Japan

Aboveground biomass and litterfall ofPinus pumila scrubs, growing on the Kiso mountain range in central Japan, were investigated from 1984 to 1985. The biomass of two research plots (P1 and P2) with different scrub heights was estimated by two methods, the stratified clip technique and the allometric method. Aboveground total biomass estimated by the latter method reached 181 ton d.w. ha⁻¹ in P1 and 132 ton d.w. ha⁻¹ in P2. Creeping stems contributed to about half of the total biomass. Although estimates of woody organs differed between the two plots, leaf biomass estimates were almost the same at 15.5 ton d.w. ha⁻¹. The canopies of the twoP. pumila scrubs were characterized by a large mean leaf area density of 5.0 m² m⁻³. Despite this large area density, relatively moderate attenuation of light intensity was observed. Specific leaf area generally increased with reduced leaf height. Annual total litterfall was estimated to be 3.60 ton d.w. ha⁻¹ yr⁻¹ in P1 and 2.39 ton d.w. ha⁻¹ yr⁻¹ in P2. Annual leaf fall in both plots was approximately 2.0 ton d.w. ha⁻¹ yr⁻¹. Leaves fell mainly in early autumn. Annual loss rates of branches, estimated as the sum of annual branch litterfall and the amount of newly formed attached dead branches, were 0.29 ton d.w. ha⁻¹ yr⁻¹ in P1 and 0.37 ton d.w. ha⁻¹ yr⁻¹ in P2.     

Effect of phenylalanine and phenylpropanoids on the accumulation of capsaicinoids and lignin in cell cultures of chili pepper (<Emphasis Type="Italic">capsicum annuum</Emphasis> L.)

Summary Chili pepper (Capsicum annuum L., cv. Tampique?o 74) cell suspensions were employed to study the influence of phenylalanine and phenylpropanoids on the total production of capsaicinoids, the hot taste compounds of chili pepper fruits. The effect of capsaicinoid precursors and intermediates on the accumulation of lignin as an indicator of metabolic diversion was also investigated. Addition of 100 μM of either phenylalanine, cinnamic or caffeic acids to chili pepper cell cultures did not cause significant increases in total capsaicinoids (expressed as capsaicin content, and calculated as averages of the measured values) during the growth cycle. The highest total capsaicinoid content was recorded in cultures grown in the presence of vanillin (142.61 μg g⁻¹ f.wt.), followed by cells treated with 100 μM vanillylamine (104.88 μg g⁻¹ f.wt.), p-coumaric acid (72.36 μg g⁻¹ f.wt.). and ferulic acid (34.67 μg g⁻¹ f.wt.). Capsaicinoid content for control cells was 13.97 μg g⁻¹ f.wt. Chili pepper cell suspensions cultured in the presence of 100 μM of either phenylalanine, or cinnamic, caffeic, or ferulic acids, or the same concentration, of vanillin and vanillylamine, did not exhibit statistically significant differences in the content of lignin as compared with control cells. However, addition of p-coumaric acid (100 μM) to the cultute medium significantly increased thelignin production (c. 10–15 times the contents of control cells).     

Seasonal changes in growth rate, carrageenan yield and lectin content in the red alga Kappaphycus alvarezii cultivated in Camranh Bay, Vietnam

The three color morphotypes of the red alga Kappaphycus alvarezii (brown, red and green) were cultured in Camranh Bay, Vietnam, using the fixed off-bottom monoline culture method to evaluate the growth rate, carrageenan yield, 3,6-anhydrogalactose, gel strength and lectin content. The brown morphotype was cultivated over a 12-month period; the red and green morphotypes were over a 6-month period. At the 60-day culture timepoint, the brown morphotype showed a higher growth rate (3.5–4.6% day⁻¹) from September to February, and lower growth rate (1.6–2.8% day⁻¹) from March to August. Significant (P < 0.05) differences in growth rate between culture months were found with the brown morphotype. High growth rates for the red (3.6–4.4% day⁻¹) and green (3.7–4.2% day⁻¹) morphotypes were obtained from September to February. The carrageenan yield, 3,6-anhydrogalactose and gel strength of the three morphotypes showed little variation, with the highest values obtained in November–December. At the 30-day sampling point, the brown morphotype had a higher lectin content (167–302 μg g⁻¹ dry alga) from August to March and a lower lectin content (23–104 μg g⁻¹ dry alga) from April to July. High lectin contents were recorded for the red (139–338 μg g⁻¹ dry alga) and green (124–259 μg g⁻¹ dry alga) morphotypes from September to February. This study shows that the different morphotypes of K. alvarezii can be grown in the tropical waters of the Camranh during the northeast monsoon, and part of the southwest monsoon, especially the brown morphotype, which can be grown during any season.