Fresh Weight Gain Research Articles

Sterol and sesquiterpenoid biosynthesis during a growth cycle of tobacco cell suspension cultures

The accumulation and biosynthesis of sterols and fungal elicitor-inducible sesquiterpenoids by tobacco (Nicotiana tabacum) cell suspension cultures were examined as a function of a 10 day culture cycle. Sterols accumulated concomitantly with fresh weight gain. The rate of sterol biosynthesis, measured as the incorporation rate of [(14)C]acetate and [(3)H]mevalonate, was maximal when the cultures entered into their rapid phase of growth. Changes in squalene synthetase enzyme activity correlated more closely with thein vivo synthesis rate and accumulation of sterols than 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) enzyme activity. Cell cultures entering into the rapid phase of growth also responded maximally to fungal elicitor as measured by the production of capsidiol, an extracellular sesquiterpenoid. However, the rate of sesquiterpenoid biosynthesis, measured as the incorporation rate of [(14)C]acetate and [(3)H]mevalonate, could not be correlated with elicitor-inducible HMGR or sesquiterpene cyclase enzyme activities, nor elicitor-suppressible squalene synthetase enzyme activity.

Effects of Cold Acclimation on the Morphological and Physiological Properties of Alfalfa ( Medicago sativa) Suspension Culture Cells

Cell suspension cultures of alfalfa (Medicago sativa L. cv. Rangelander) maintained at 2°C for 14 days were much more resistant to freezing-induced damage than cultures maintained at 21 °C. While no gain in fresh weight occurred during acclimation, such cells had smaller vacuoles and appeared to have more membranous material in their cytoplasm. The latter observation was supported by cell fractionation studies which indicated that the acclimated cells contained more microsomal phospholipid and protein than control cells. In contrast, the total solute content was lower in acclimated compared to control cells. Acclimation increased the relative content of phospholipids and decreased the sterol content of membranes. Also the phospholipids of acclimated cells had a higher percentage of unsaturated fatty acyl chains than those of control cells. As a result, the fluidity of liposomes prepared from membrane lipids, measured by fluorescence depolarization, was higher for preparations from acclimated cells than the control cells. The results suggest that membrane modification, during low temperature culture, is a major component of the cold acclimation process in alfalfa cells and that the adjustments which occur in the solute and water content of the cells are minor components of the process.

The effect of gamma radiation and N-ethyl-N-nitrosourea on cultured maize callus growth and plant regeneration

Regenerable maize calli of two inbred lines were exposed to 0 to 100 Gy of gamma rays or treated with 0 to 30 mM of N-ethyl-N-nitrosourea (ENU) to determine their effect on growth and plant regeneration capability. Both growth and plant regeneration capacity decreased with increasing levels of either gamma radiation or ENU; however, plant regeneration capacity was more sensitive to either agent than growth. The 50% inhibition dose (I50) for callus growth (fresh-weight gain) was approximately 100 Gy of gamma radiation and 30 mM ENU. The I50 for plant regeneration capacity of treated callus was approximately 25 Gy of gamma radiation and 2.5 mM ENU. The decrease in plant regeneration capacity correlated with a change in tissue composition of the treated callus from a hard, yellow and opaque tissue to a soft, grayish-yellow and translucent tissue. This change was quantified by measuring the reduction of MnO4 - to MnO2 (PR assay) by the callus. These results suggest that the effect of gamma radiation or ENU on plant regeneration capacity must be taken into consideration if these potentially mutagenic agents are to be used on maize callus cultures, for the purpose of producing useful mutations at a whole plant level. The data also suggest that the PR assay may be useful for predicting the actual plant regeneration capacity of maize callus.

Nonchemical Methods for Postharvest Control of Botrytis cinerea on Cut Roses

Abstract Cold storage of cut ‘Sonia’, ‘Royalty’, and ‘Gold Rush’ roses (Rosa hybrida L.) at reduced humidities (50% to 80% RH) significantly decreased the severity of Botrytis cinerea Pers. infections that developed from naturally occurring or experimentally applied inocula, compared to storage at saturated humidity. The disease reduction was attributed to the absence of free water on the petals. Wrapping the flowers in cellophane sleeves before reduced-humidity storage decreased water loss but also impaired disease control. No deleterious effects of reduced-humidity storage on poststorage fresh weight gain or visual quality were observed, whether the wrapped flowers are stored with or without vase solutions. Two biological control agents, the yeast Exophiala jeanselmei and a Coryneform-type bacterium, controlled B. cinerea infections during storage at 2.5°C when applied 0 to 48 hr after inoculation with the pathogen. The level of disease control achieved with the biological antagonists during storage was comparable to that achieved with the fungicide vinclozolin, but the biological antagonists did not control poststorage disease development as well.

Monitoring chilling injury: A comparison of chlorophyll fluorescence measurements, post‐chilling growth and visible symptoms of injury in Zea mays

Changes in chlorophyll fluorescence emission from maize (Zea mays L. cv. Northern Belle) seedlings chilled at 1.5°C in the dark for 3–30 h were compared with the ability of plants to resume growth in the immediate post‐chilling period and with the development of visible symptoms of injury to the leaves. During chilling, the maximal rate of increase of the induced chlorophyll fluorescence rise. FR, was measured on secondary leaf tissue. FR decreased exponentially, at approximately the same rate in plants grown and chilled in hydroponic pots, in leaves detached from similar plants and in plants that were removed from the hydroponic pots and laid on wet filter paper adjacent to the detached leaves. The half‐fall time for FR in the 3 treatments was 7.8 ± 1.3 h, 8.6 ± 0.6 h and 8.8 ± 1.0 h, respectively. Following seedling removal from 1.5°C and return to 25/15°C, relative growth rates were determined from daily measurements of plant fresh weight gain. Compared with non‐chilled seedlings, plants chilled for 3 h and longer showed depressed rates of growth. Inhibition of growth in the immediate post‐chilling period (0–27 h) was linearly related to the duration of the chilling period and had a high positive correlation with the decrease in chlorophyll fluorescence (linearly related to log FR) sustained during the chilling exposure. Visible symptoms of chilling injury developed during the post‐chilling period on seedlings chilled for longer than 3 h. The decrease in log FR during chilling was also linearly correlated with the severity of visual symptoms of chilling injury expressed in the post‐chilling period. It is concluded that the extent of chilling injury in maize can be rapidly and non‐destructively assessed from measurements of chlorophyll fluorescence.

Effects of CO2 and photosynthetic photon flux on yield, gas exchange and growth rate of Lactuca sativa L. 'Waldmann's Green.'

Enrichment of CO2 to 46 mmol m-3 (1000 mm3 dm-3) at a moderate photosynthetic photon flux (PPF) of 450 micromoles m-2 s-1 stimulated fresh and dry weight gain of lettuce leaves 39% to 75% relative to plants at 16 mmol m-3 CO2 (350 mm3 dm-3). Relative growth rate (RGR) was stimulated only during the first several days of exponential growth. Elevating CO2 above 46 mmol m-3 at moderate PPF had no further benefit. However, high PPF of 880-900 micromoles m-2 s-1 gave further, substantial increases in growth, RGR, net assimilation rate (NAR) and photosynthetic rate (Pn), but a decrease in leaf area ratio (LAR), at 46 or 69 mmol m-3 (1000 or 1500 mm3 dm-3) CO2, the differences being greater at the higher CO2 level. Enrichment of CO2 to a supraoptimal level of 92 mmol m-3 (2000 mm3 dm-3) at high PPF increased leaf area and LAR, decreased specific leaf weight, NAR and Pn and had no effect on leaf, stem and root dry weight or RGR relative to plants grown at 69 mmol m-3 CO2 after 8 d of treatment. The results of the study indicate that leaf lettuce growth is most responsive to a combination of high PPF and CO2 enrichment to 69 mmol m-3 for several days at the onset of exponential growth, after which optimizing resources might be conserved.

A dynamic simulation model for growth of the African catfish, Clarias gariepinus (Burchell 1822) : IV. The effect of feed formulation on growth and feed utilization

A dynamic simulation model is used to calculate growth of Clarias gariepinus (Burchell) fed with differently formulated diets. To verify the calculations, the results of the simulation are compared with experimental data. The experiments were carried out to determine the growth performance of C. gariepinus, fed with diets containing different protein sources. A fish meal diet was fed at four feeding levels in a respiration experiment. The alternative sources (blood meal, casein, groundnut, cottonseed, rapeseed and soybean) were tested at various inclusion rates with fish meal in aquarium experiments at one feeding level. Both experiments lasted two periods of 4 weeks each. The output of the simulation model, being fresh weight gain, protein gain, fat gain, oxygen consumption and ammonia production, agreed well with results from the respiration experiment, except for fat gain at the highest feeding levels and ammonia production in the second experimental period. It was shown that C. gariepinus is able to convert feed nutrients very efficiently into fish biomass. A protein conversion efficiency of nearly 60% was found. In the aquarium experiments the fresh weight gain decreased when an increasing part of the fish meal was replaced by alternative protein sources. The output of the simulation model (fresh weight gain) in comparison with the experimental results showed that it is possible to calculate the weight conversions of differently formulated diets, when there is a reliable estimation of the amino acid composition of the protein sources used.

GROWTH OF GEOCORIS PUNCTIPES (HEMIPTERA: LYGAEIDAE) ON ATTACHED AND DETACHED LEAVES OF PEST-RESISTANT SOYBEANS

A field experiment using attached soybean, Glycine max (L.) Merrill, leaves showed that fresh weight gain of Geocoris punctipes (Say) (Hemiptera: Lygaeidae) nymphs between days 14 and 21 was greater on ‘Govan’ and ‘Bragg’ leaves than on leaves of PI229358. Weight gain on ‘Govan’ leaves was greater than on PI171451 leaves. In the same experiment, there were no differences in fresh weight growth of G. punctipes nymphs on detached leaves of the four genotypes.

Organogenesis and plantlet regeneration following in vitro cold storage of kiwifruit shoot tip cultures

Shoots were cut from kiwifruit ( Actinidia deliciosa (A. chev.) C.F. Liang et A.R. Ferguson var. deliciosa) shoot tip cultures which had been stored at 8°C for 52 weeks, from 52-week-old cultures continuously maintained at the shoot proliferation stage at 23°C, and from 8-week-old proliferating cultures. The excised shoots were re-cultured in proliferation medium for 1 month and in vitro organogenesis was examined. There was no difference between the three types of shoot cultures in fresh weight gain or in shoot production, but the number of roots produced was greater in the shoot cultures derived from the cold-stored cultures than in those derived from the cultures maintained at the proliferation stage. All plantlets regenerated from all three treatments survived. Therefore, storage of kiwifruit shoot tip cultures in vitro for 52 weeks at 8°C did not impair subsequent in vitro organogenesis of sub-cultured shoots or plantlet regeneration.

A dynamic simulation model for growth of the African catfish, Clarias gariepinus (Burchell 1822) : III. The effect of body composition on growth and feed intake

A feeding experiment was conducted in aquaria to study the effect of body composition on growth and feed intake of Clarias gariepinus. Fishes weighing about 20 g were fed diets with different protein to fat ratios. Diet A contained 60% protein, 7% fat and 19% carbohydrate. The composition of diet B was 20% protein, 7% fat and 54% carbohydrate. After 4 weeks the mean fish weight per tank amounted 33.2±1.5 and 27.5±1.4 g for fish fed diets A and B, respectively, while the fat content of the fish was 3.6±0.3 and 6.1±0.4%. During two consecutive periods of 21 days both the lean and the fat fish were fed diet A or B at five feeding levels. The feeding levels ranged from maintenance to above satiation. Fresh weight gain, protein gain and fat gain were higher with increasing feed ration, until a maximum was reached where extra feed did not result in more gain. This maximum gain was higher for diet A. Feeding with this high-protein diet resulted in better feed conversions compared with diet B. Within one diet, lean fish had a higher maximum growth rate compared to fat fish due to a higher feed consumption. Below the maximum gain, fat fish showed a slightly better conversion efficiency when fed with diet A. A explanatory model, for simulating growth of C. gariepinus, was extended in accordance with these experimental findings. It is assumed that the maximum consumption is regulated by both lipostatic and glucostatic mechanisms. The relevant parameter values were fitted with results obtained in the second experimental period. The adjusted model was tested by comparing simulation with experimental results found in the third period. The model gives good results for feeding levels providing sub-maximum gain. At the highest feeding levels of diet A, fed to initially fat fish, the model overestimated gain. The model was used to predict fresh weight gain of C. gariepinus fed diets with different compositions.

A dynamic simulation model for growth of the African catfish, Clarias gariepinus (Burchell 1822) : II. Effect of feed composition on growth and energy metabolism

A dynamic simulation model was adapted to investigate the effect of feed composition on growth of Clarias gariepinus. The effect of feed composition was restricted to that of the macronutrients, i.e. protein, fat and carbohydrates. Most parameters used in the model were derived from the literature. Parameters which were expected to have specific values for the species used, or which could not be derived from the literature, were calibrated with experimental results. Results used for calibration originate from an 84-day feeding trial with 20 different semi-moist diets. The protein content of these varied from 20 to 60% and the fat content from 0 to 38%. Data used to test the model originated from balance respiration experiments. In these experiments dietary protein content varied from 20 to 40% and fat content from 4 to 29%. A dry pelleted feed was used in these experiments. The test results of the model for fresh weight gain, protein gain, fat gain and oxygen consumption were compared with the independently obtained results of the balance respiration experiments. It is concluded that the model predicts reasonably well the effects of feed composition on growth and growth composition. The predicted values are in agreement with the observed values, except for the diets with the highest fat content. With these diets the predictions are overestimated. During the modelling procedure it became apparent that feed intake is influenced by the fat content of the fish biomass. Fat fish consume less than leaner fish of the same weight.

Cut Flower Longevity of Peony

Abstract Flower longevity (as influenced by stage of maturity at harvest), dry weight, and flower preservative were studied using cut flowers of herbaceous peony (Paeonia spp.) cultivars Felix Crousse, Festiva Maxima, John C. Lee, Mons. Jules Elie, and Richard Carvel. Flowers harvested in the tight calyx stage frequently failed to open or opening was delayed. No substantial difference in longevity between flowers harvested at the loose calyx stage or first loose petal stage was found. Those cut at the loose calyx stage maintained quality well during dry storage at 0°C for up to 4 weeks. Vase-life and days to opening differed significantly with cultivar, length of storage, and their interaction. Fresh weight increased before or during flower opening, and the increase was greater after storage than for unstored flowers. Inclusion of a floral preservative in the vase solution increased gain in fresh weight upon hydration after storage and weight throughout vase-life.

Increase in esterase activity during maturation of Malus pumila fruit

SUMMARYIn a range of dessert cultivars of Malus pumila, the esterase in the fruit showed a rise in activity during the period of fresh weight gain. This was the case when activity was expressed on a protein or a fresh weight basis. Both fruit which matured at 100 days after anthesis, and fruit which matured later, showed a similar rate of increase. However, a cultivar used for processing rather than eating showed a much reduced rate of esterase increase.

Adaptation of Tobacco Cells to NaCl

Cell lines of tobacco (Nicotiana tabacum L. var Wisconsin 38) were obtained which are adapted to grow in media with varying concentrations of NaCl, up to 35 grams per liter (599 millimolar). Salt-adapted cells exhibited enhanced abilities to gain both fresh and dry weight in the presence of NaCl compared to cells which were growing in medium without NaCl (unadapted cells). Tolerance of unadapted cells and cells adapted to 10 grams per liter NaCl was influenced by the stage of growth, with the highest degree of tolerance exhibited by cells in the exponential phase. Cell osmotic potential and turgor varied through the growth cycle of unadapted cells and cells at all levels of adaptation, with maximum turgor occurring at approximately the onset of exponential fresh weight accumulation.Adaptation to NaCl led to reduced cell expansion and fresh weight gain, while dry weight gain remained unaffected. This reduction in cell expansion was not due to failure of the cells to maintain turgor since cells adapted to NaCl underwent osmotic adjustment in excess of the change in water potential caused by the addition of NaCl to the medium. Tolerance of the adapted cells, as indicated by fresh or dry weight gain, did not increase proportionately with the increase in turgor. Adaptation of these glycophytic cells to NaCl appears to involve mechanisms which result in an altered relationship between turgor and cell expansion.

Leaf Carbohydrate Status and Enzymes of Translocate Synthesis in Fruiting and Vegetative Plants of Cucumis sativus L.

Carbon partitioning in the leaves of Cucumis sativus L., a stachyose translocating plant, was influenced by the presence or absence of a single growing fruit on the plant. Fruit growth was very rapid with rates of fresh weight gain as high as 3.3 grams per hour. Fruit growth was highly competitive with vegetative growth as indicated by lower fresh weights of leaf blades, petioles, stem internodes and root systems on plants bearing a single growing fruit compared to plants not bearing a fruit. Carbon exchange rates, starch accumulation rates and carbon export rates were higher in leaves of plants bearing a fruit. Dry weight loss from leaves was higher at night from fruiting plants, and morning starch levels were consistently lower in leaves of fruiting than in leaves of vegetative plants indicating rapid starch mobilization at night from the leaves of fruiting plants. Galactinol, the galactosyl donor for stachyose biosynthesis, was present in the leaves of fruit-bearing plants at consistently lower concentration than in leaves of vegetative plants. Galactinol synthase, and sucrose phosphate synthase activities were not different on a per gram fresh weight basis in leaves from the two plant types; however, stachyose synthase activity was twice as high in leaves from fruiting plants. Thus, the lower galactinol pools may be associated with an activation of the terminal step in stachyose biosynthesis in leaves in response to the high sink demand of a growing cucumber fruit.

Partitioning of assimilates in fruiting tomato plants

Tomato is a potentially high-yield crop with a harvest index of about 65%. During fruiting, fruit growth accounts for 80 to 90% of the plant fresh weight gain and fruits are therefore the strongest sinks for assimilate. At initiation, an inflorescence is a weak sink in comparison with apical shoots. When assimilate supply is inadequate, the inflorescence has a reduced level of endogenous cytokinin and the degree of abortion is inversely related to the activity of sucrose hydrolase. Application of cytokinin plus gibberellins to the inflorescence increases its capacity to attract assimilate at the expense of apical shoots. At fruit set, cell division is activated and the ovary starts to accumulate reducing sugars and starch. Both the final cell number and the potential cell size are determined in the first two weeks and may be related to the levels of cytokinin and auxin. At the early stage of rapid growth a fruit accumulates imported assimilates, mainly in the forms of hexoses and starch. The rate of starch accumulation increases with the absolute fruit growth rate and affects the final soluble solids content of a fruit. The change in the fruit growth rate during fruit development does not coincide with the changes in the endogenous hormone levels of the fruit. A fruit competes for assimilate with others mainly in the same truss.

English walnut fruit growth and development

Samples of the ‘Ashley’, ‘Hartley’ and ‘Franquette’ cultivars of English walnut ( Juglans regia L.) were collected at weekly intervals from bloom to harvest, and development of the fruit, embryo and surrounding tissue was followed. The first division of the zygote occurred approximately one week after pollination, by which time the endosperm, nucellus and integument had shown considerable growth. The endosperm first formed cell walls at the 8-celled embryo stage and was completely cellular by the time the embryo contained approximately 64 cells. Rapid growth of the cotyledons started as the shell began to harden at Week 7. Measurement of fruit growth indicated that fresh weight gain in ‘Ashley’ and ‘Hartley’ fruits followed a double sigmoid pattern, characterized by a 3-week period of slowed growth that began approximately 7 weeks after bloom. Rate of increase in total length and diameter also slowed greatly at Week 7. Fresh weight gain in ‘Franquette’ appeared to follow a single sigmoid curve, with no prolonged period of slowed growth corresponding to that in the other cultivars. Kernel growth also described a double sigmoid curve, with its initial, rapid phase nearly coincident with the beginning of Stage III of the whole-fruit, fresh-weight curve at Week 10.

Leaf Symptoms, Yield, and Composition of Mineral-deficient American Ginseng1

Abstract In a study of nutrient requirements of American ginseng (Panax quinquefolium L.) foliar deficiency symptoms of Ca occurred first, followed by those for Mg and P. N-deficiency symptoms occurred very gradually, and S-deficiency symptoms never appeared. Root fresh weight gain was most restricted by omission of either Ca, P, or Mg from the nutrient solution. Omission of S resulted in a root fresh weight gain equal to that obtained with complete nutrient solution.

Growth regulator inhibition of tobacco callus growth

The activity of two groups of growth regulators, substituted dinitroanilines and nitrophenylhydrazines, were evaluated in a tobacco ( Nicotiana tabacum L. “X-73”) callus tissue bioassay. Molar concentrations required to inhibit fresh weight gain by 50% (I 50) was determined by using linear regression analysis on data obtained by testing a range of five concentrations of each chemical. All chemicals tested were inhibitory to callus tissue grown in the dark. Cell division seemed to be the primary activity inhibited. The most active of the dinitroaniline series was α,α,α-trifluoro-2,6-dinitro- N-ethyl- N-2′,6′-dichlorobenzyl- p-toluidine ( I) (I 50 = 1.5 × 10 −10 M). I and two other N-(o-halobenzyl) dinitroanilines were more active than α,α,α-trifluoro-2,6-dinitro- N-ethyl- N-2′-chloro-6′-fluorobenzyl- p-toluidine ( IV), which is being developed commercially for suppression of axillary buds in tobacco. The two most active nitrophenylhydrazines tested were 1,1-dimethyl-2-(2′,6′-dinitro-3′- n-propylamino-α,α,α-trifluoro- p-tolyl)hydrazine ( XVIII) and 3′,5′-dinitro- p-(2,2-diethylhydrazino)- N-methoxy- N-methylbenzamide ( XIX) (I 50 values of 7.9 × 10 −9 and 9.3 × 10 −9 M, respectively). Factors such as electronic distribution, steric hindrance, and lipid solubility were considered to influence the biological activity of the compounds tested.

Physiological and Nutritive Effects of K-Pretreatment and KCl Sprays on Water-stressed and Unstressed Apple Seedlings1

Abstract Low- and high-K pretreated ‘York Imperial’ apple seedlings (Malus domestica Borkh.) were grown in nutrient solution cultures. Addition of polyethylene glycol (PEG) to the nutrient solution to reduce water potential to −1.0 bar reduced water consumption, fresh weight, specific leaf weight (SLW), and leaf water potential and increased the amount of water consumed per unit of fresh weight gain. High-K pretreatment increased water consumption of unstressed seedlings but decreased water consumption of PEG-stressed plants. Daily sprays with 0.5% KCl applied in early afternoon had no effect on water consumption rate in apple seedlings. However, sprays probably induced wider stomatal opening, since K-sprayed trees had lower leaf water potential when measured at noon than unsprayed trees. This effect was not observed when water potential was measured in the morning (0800 hr). High-K plants had higher leaf water potential than low-K plants in the morning. Potassium pretreatment and PEG stress as well as K-sprays had numerous effects on plant mineral composition. The K-pretreatment or K-sprays did not alleviate the detrimental effects of PEG-induced water stress despite the effects of K-pretreatment and K-sprays on mineral composition and leaf water potential.