Search Results

You are looking at 41 - 50 of 943 items for :

Clear All
Free access

Raul De la Rosa, Luis Rallo and Hava F. Rapoport

In the olive (Olea europaea L.), inflorescence and flower differentiation occur in the early spring following a period of winter chilling and dormancy of the potentially reproductive buds. We examined the size, structure, and starch content of these buds during winter rest in the field and during forcing under standard growth-chamber conditions. Basic bud structure and dimensions remained unchanged during the rest period, but starch content increased in the bud's central axis. When cuttings were forced in the growth chamber, the buds followed a morphogenetic pattern similar to that observed in the field, but the sequence of developmental events could be timed more precisely. The first changes observed were the onset of axis growth and the differentiation of axillary primordia within 3 days of transfer to the growth chamber. This was followed by the initiation of new nodes, and, at 15 to 18 days, by the first signs of floral differentiation in the terminal and axillary bud apical meristems. Bud growth and differentiation were accompanied by a decrease in starch content.

Full access

Anna Marín, Anne Plotto, Lorena Atarés and Amparo Chiralt

time, respectively. C = control (water dispersion); CFU = colony-forming unit; LAB = L. plantarum ; NaC = sodium caseinate, OA = oleic acid; PS = pregelatinized potato starch. After 7 d of storage, the survival of L. plantarum showed a significant

Free access

Seong-Tae Choi, Doo-Sang Park, Seong-Mo Kang and Seong-Koo Kang

; Park et al., 2003 ). The reserve N compounds are present as amino acids and proteins and the reserve carbohydrates as soluble sugars and starch ( Cheng et al., 2004 ; Oliveira and Priestley, 1988 ; Titus and Kang, 1982 ). A negative relationship

Free access

Guoqiang Hou and Jack W. Buxton

Through control of light intensity and CO, concentrations, three levels of starch (low, medium and high) in marigold seedlings existed at sunset. The range in starch concentration represented that encountered under average greenhouse conditions. For each starting starch concentration, an optimum temperature was initially determined based on first and second order reactions on the corresponding starch decline curve. Every day, during seedling growth in the greenhouse, the starch concentration at sunset was predicted based on primarily the quantity of light received throughout the day; the night temperature was adjusted to the predicted optimum night temperature setting. Based on these studies a significant improvement in seedling growth can be achieved with significantly less heating cost.

Full access

Yung-Kun Chuang, I-Chang Yang, Chao-Yin Tsai, Jiunn-Yan Hou, Yung-Huei Chang and Suming Chen

competition of international markets. Previous studies have indicated that carbohydrates, hormones, and minerals are related to the growth of Phalaenopsis plants ( Chen et al., 1994 ; Kataoka et al., 2004 ). Among them, starch is one type of carbohydrate

Free access

K.I. Theron and G. Jacobs

Flowering-size Nerine bowdenii bulbs were sampled from a commercial planting at 2-week intervals from 13 Aug. 1991 to 14 June 1992. They were dissected, the dry weight of foliage and leaf bases was recorded, and carbohydrate analysis was performed on the foliage leaves, leaf bases, and roots. Starch was the dominant storage carbohydrate, and leaf bases were the principal bulb structures where it was stored. Changes in starch content closely followed dry weight changes in the bulb. When exposed to low temperatures, starch was converted to sugars. Except for these high levels in the leaf bases, sugars, expressed both as concentration and total content, were low in bulb components, indicating continued export and conversion to starch. Low sugar levels during the period that florets in the current season's inflorescence develop to stage Late G (gynoecium elongated, carpels fused) is implicated in the abortion of the inflorescence.

Free access

Rui Zhou, Lailiang Cheng and Abhaya Dandekar

The reaction catalyzed by ADP-glucose pyrophosphorylase (AGPase) to form ADP-glucose is a regulatory and rate-limiting step in starch synthesis in plants. In response to decreased sorbitol synthesis, starch synthesis was up-regulated in the transgenic apple plants. In this study, we examined both redox and metabolite regulation of AGPase to understand the mechanism responsible for the up-regulation of starch synthesis. No difference in the monomerization/dimerization of apple leaf AGPase small subunits was observed between the transgenic plants and the untransformed control. NADP-dependent malate dehydrogenase, indicative of chloroplastic redox status, did not show significant change in the transgenic plants either. Determination of key metabolites with nonaqueous fractionation indicated that concentrations of hexose phosphates (mainly glucose-6-phosphate and fructose-6-phosphate) were higher in both the cytosol and chloroplasts of the transgenic plants than in the control, whereas 3-phosphoglycerate (PGA) concentration in the chloroplast was not higher in the transgenic plants. We conclude that accumulation of hexose-phosphates results in a decrease in inorganic phosphate (Pi) concentration and an increase in PGA/Pi ratio in the chloroplast, leading to up-regulation of starch synthesis via activating AGPase.

Free access

Richard C. Rosecrance, Steven A. Weinbaum and Patrick H. Brown

The effect of crop load on nutrient and starch storage in mature, alternate-bearing pistachio trees was examined. Tree storage pools were estimated from the differences in nutrient and starch contents of perennial tree parts between dormancy (the period of highest nutrient and starch content) and following spring flush (the period of lowest nutrient and starch content). Following a lightly cropping (off) year, trees contained significantly larger N, P, and K storage pools than following a heavily cropping (on) year. The relative contribution of leaf nutrient resorption to tree nutrient storage pools varied depending on the crop load. Nutrient storage is a function of net leaf nutrient resorption and current uptake from the soil. Leaf nutrient (N, P, and K) resorption was a more significant component of nutrient storage in on-year than off-year trees. The contribution of nutrient storage to shoot (i.e., leaves, fruit, current-year wood) nutrient contents was evaluated following the spring flush (May) and nut fill (September) periods. Nutrient storage pools are an important source of nutrients during the spring flush of growth, but nutrient demands during nut fill are met primarily by current nutrient uptake from the soil. The relationships between nutrient storage and uptake are discussed.

Free access

Gary W. Stutte, Neil C. Yorio and Raymond M. Wheeler

The effect of photoperiod (PP) on net carbon assimilation rate (Anet) and starch accumulation in newly mature canopy leaves of `Norland' potato (Solanum tuberosum L.) was determined under high (412 ∝mol·m-2·s-1) and low (263 ∝mol·m-2·s-1) photosynthetic photon flux (PPF) conditions. The Anet decreased from 13.9 to 11.6 and 9.3 μmol·m-2·s-1, and leaf starch increased from 70 to 129 and 118 mg·g-1 drymass (DM) as photoperiod (PP) was increased from 12/12 to 18/6, and 24/0, respectively. Longer PP had a greater effect with high PPF conditions than with low PPF treatments, with high PPF showing greater decline in Anet. Photoperiod did not affect either the CO2 compensation point (50 μmol·mol-1) or CO2 saturation point (1100-1200 μmol·mol-1) for Anet. These results show an apparent limit to the amount of starch that can be stored (≈15% DM) in potato leaves. An apparent feedback mechanism exists for regulating Anet under high PPF, high CO2, and long PP, but there was no correlation between Anet and starch concentration in individual leaves. This suggests that maximum Anet cannot be sustained with elevated CO2 conditions under long PP (≥12 hours) and high PPF conditions. If a physiological limit exists for the fixation and transport of carbon, then increasing photoperiod and light intensity under high CO2 conditions is not the most appropriate means to maximize the yield of potatoes.

Full access

Torrance R. Schmidt, Don C. Elfving, James R. McFerson and Matthew D. Whiting

equator; calyx halves were treated with 10% iodine solution for standard starch readings (0–6-point scale) and tissue pieces from the stem halves of each fruit were mechanically juiced to produce a bulk sample for evaluation of soluble solids concentration