Photosynthesis in vine leaves as a function of light intensity, temperature, and leaf age

Photosynthesis and respiration were measured in the laboratory with an infrared CO2 analyser using attached leaves on Sultana vines growing either in the glasshouse or out of doors. At light saturation (2,500-3,000 f. c.) the photosynthetic rates approximated 8.5 and 10.5 mg CO/h/dm2 with light compensation points of 50 and 125 f. c. respectively. The optimum temperature for photosynthesis was between 25 and 30° C.Age effects were examined using shoots from well established field vines. Small but rapidly expanding terminal leaves showed no net photosynthesis but had a high rate of dark respiration and a CO2 compensation point above 300 ppm. With further expansion the leaves showed a steady increase in photosynthetic activity with a corresponding decline in dark respiration and CO2 compensation point. The rate of photosynthesis again declined with the onset of senescence

Leaf age and photosynthesis in Vitis vinifera L.

The photosynthetic activity of individual vine leaves was measured on potted plants grown out doors, using both infrared C02 analysis and 14C02 fixation techniques. Peak photosynthetic activity occurred at the time when the leaf became fully expanded, approximately 40 days after unfolding. Thereafter, photosynthesis declined gradually.The increase in photosynthesis during leaf expansion was not attributable to increased chlorophyll concentration, altered spectral characteristics, or to any outstanding anatomical change. Nevertheless, a sensecent leaf was readily distinguished anatomically from an expanding or mature leaf.Irrespective of leaf age, sucrose was the major 14C02 fixation product. Oligo- saccharides also incorporated label, and accounted for a higher proportion of the 14C fixation products in older leaves. Regardless of leaf age, malic and citric acids became labelled, but the formation of 14C tartaric acid was restricted to the rapidly expanding foliage. The amino compounds serine and aspartic acid showed some incorporation of label in all leaves examined

Anatomical aspects of grape berry development

The anatomical development of the sultana-grape berry has been followed from anthesis to maturity on material grown under glasshouse and field conditions including field-grown clonal lines differing in final fruit size. Fresh weight, volume, berry dimensions, moisture content and dry weight were measured on whole berries. Pericarp growth was studied at the cell level. Pericarp growth is basically responsible for the overall growth of the berry and this tissue represents 64% of the mature fruit's total volume. The period required for complete berry development (approximately 100 days) falls into two major growth periods separated by a lag phase. Before the lag phase pericarp growth results partly from cell division but mainly from cell enlargement. After the lag phase pericarp growth results entirely from cell enlargement. Cell division in the pericarp ceases about one week before the lag phase. Berry size differences between clonal lines were primarily due to differences in the size of pericarp cells. Berry size differences between fruits grown in the glasshouse and in the field at Merbein were due to differences in both pericarp cell number and cell size

Grape berry respiration: Effects of metabolic inhibitors

The rate of O2 uptake, respiratory quotient and the effects of metabolic inhibitors on respiration were followed throughout berry development of 4 varieties of Vitis vinifera L. No obvious differences in respiratory characteristics were found between seeded and seedless and between pigmented and nonpigmented grapes.Physiological differences between immature and maturing grape berries involve altered rates of respiration and a changed sensitivity to metabolic inhibitors. With development in all varieties there was a decline in O2 uptake on a fresh weight basis while R.Q. values rose to greater than unity. Dinitrophenol failed to stimulate O, uptake at any stage and the inhibition of O2 uptake caused by azide or DNP was more severe in mature fruit than in immature fruit. Cyanide stimulated O2 uptake in tissue slices from immature Sultana berries but inhibited O2 uptake in slices from more developed fruit.These data, coupled with the absence of any major alteration in the level of insoluble nitrogen per unit fresh weight of berry suggest that respiration is both quantitatively and qualitatively different in immature compared with maturing grape berries

Midday measurements of leaf water potential and stomatal conductance are highly correlated with daily water use of Thompson Seedless grapevines

A study was conducted to determine the relationship between midday measurements of vine water status and daily water use of grapevines measured with a weighing lysimeter. Water applications to the vines were terminated on August 24th for 9 days and again on September 14th for 22 days. Daily water use of the vines in the lysimeter (ETLYS) was approximately 40 L vine−1 (5.3 mm) prior to turning the pump off, and it decreased to 22.3 L vine−1 by September 2nd. Pre-dawn leaf water potential (ΨPD) and midday Ψl on August 24th were −0.075 and −0.76 MPa, respectively, with midday Ψl decreasing to −1.28 MPa on September 2nd. Leaf g s decreased from ~500 to ~200 mmol m−2 s−1 during the two dry-down periods. Midday measurements of g s and Ψl were significantly correlated with one another (r = 0.96) and both with ETLYS/ETo (r = ~0.9). The decreases in Ψl, g s, and ETLYS/ETo in this study were also a linear function of the decrease in volumetric soil water content. The results indicate that even modest water stress can greatly reduce grapevine water use and that short-term measures of vine water status taken at midday are a reflection of daily grapevine water us

The response of Plantago major ssp pleiosperma to elevated CO2 is modulated by the formation of secondary shoots

The effect of elevated CO2 on the relative growth rate (RGR) of Plantago major ssp. pleiosperma was studied during the vegetative stage, in relation to plant development, by growing plants at 350 mu l l(-1) or at 700 mu l l(-1) CO2 in non-limiting nutrient solution with nitrate. To minimize interference by the accumulation of non-structural carbohydrates in the interpretation of results, RGR was expressed on a f. wt basis (RGR(FW)), as were all plant weight ratios. Stimulation of the RGR(FW) Of the whole plant by elevated CO2 was transient, and did not last longer than 8 d. At the same time a transient increase in root weight ratio (RWR) was observed. In order to investigate whether the transient effect of elevated CO2 on RGR(FW) was size-dependent, the data were plotted versus total f. wt (log(e) transformed). The transient period of stimulation of RGR(FW) and of RWR by elevated CO2 was still found, but in both CO2 treatments RGR(FW) decreased after a certain plant size had been reached. This size coincided with the stage at which secondary shoots started to develop, and was reached earlier in plants grown at elevated CO2. The RGR of these secondary shoots (RGR(see)) was Still increased when the period of whole plant stimulation of RGR(FW) had ended, indicating that the development of these new sinks took priority over a continuation of the stimulation of RWR. It is hypothesized that in this Plantago subspecies the response of the RGR(FW) of the whole plants to elevated CO2 is modulated by the formation of secondary shoots. Apparently, partitioning of the extra soluble carbohydrates at elevated CO2 to this tissue takes precedence over partitioning to the roots. resulting in a cessation of stimulation of plant RGR(FW) by elevated CO2.info:eu-repo/semantics/publishedVersio

Berry Flesh and Skin Ripening Features in Vitis vinifera as Assessed by Transcriptional Profiling

Background Ripening of fleshy fruit is a complex developmental process involving the differentiation of tissues with separate functions. During grapevine berry ripening important processes contributing to table and wine grape quality take place, some of them flesh- or skin-specific. In this study, transcriptional profiles throughout flesh and skin ripening were followed during two different seasons in a table grape cultivar ‘Muscat Hamburg’ to determine tissue-specific as well as common developmental programs. Methodology/Principal Findings Using an updated GrapeGen Affymetrix GeneChip® annotation based on grapevine 12×v1 gene predictions, 2188 differentially accumulated transcripts between flesh and skin and 2839 transcripts differentially accumulated throughout ripening in the same manner in both tissues were identified. Transcriptional profiles were dominated by changes at the beginning of veraison which affect both pericarp tissues, although frequently delayed or with lower intensity in the skin than in the flesh. Functional enrichment analysis identified the decay on biosynthetic processes, photosynthesis and transport as a major part of the program delayed in the skin. In addition, a higher number of functional categories, including several related to macromolecule transport and phenylpropanoid and lipid biosynthesis, were over-represented in transcripts accumulated to higher levels in the skin. Functional enrichment also indicated auxin, gibberellins and bHLH transcription factors to take part in the regulation of pre-veraison processes in the pericarp, whereas WRKY and C2H2 family transcription factors seems to more specifically participate in the regulation of skin and flesh ripening, respectively. Conclusions/Significance A transcriptomic analysis indicates that a large part of the ripening program is shared by both pericarp tissues despite some components are delayed in the skin. In addition, important tissue differences are present from early stages prior to the ripening onset including tissue-specific regulators. Altogether, these findings provide key elements to understand berry ripening and its differential regulation in flesh and skin.This study was financially supported by GrapeGen Project funded by Genoma España within a collaborative agreement with Genome Canada. The authors also thank The Ministerio de Ciencia e Innovacion for project BIO2008-03892 and a bilateral collaborative grant with Argentina (AR2009-0021). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe