scholarly journals Photosynthesis and growth of spring barley: some effects of drought

1980 ◽  
Vol 94 (3) ◽  
pp. 623-635 ◽  
Author(s):  
J. E. Leach
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Dry Matter ◽  
Spring Barley ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Large Field ◽  
Single Leaf ◽  
Unit Leaf ◽  
Effects Of Drought

SummaryDuring the dry summer of 1976, measurements were made of the photosynthesis, transpiration, respiration, and growth of irrigated (I) and non-irrigated (NI) spring barley growing in large field plots. Using a field enclosure, the photosynthesis of the irrigated barley was measured on 19 separate days during the latter two-thirds of the growing season when the plants were large enough to have measurable gas exchanges. The response of photosynthesis to water stress was determined from 3 days' comparative measurements on the I and NI crops, using both the field enclosure and, on 2 days only, a single-leaf photosynthesis chamber.Water stress in the NI crop caused large decreases in yield: the dry-matter yields of grain and straw were respectively reduced by 19 and 27%; number of grains (but not grain mass) was also reduced. Field enclosure measurements, which were in good agreement both with values for canopy net photosynthesis derived from the leaf chamber measurements and with estimates of dry-matter production derived from plant weighings, indicated that the net CO2 uptake per unit leaf area was little affected by water stress. Results from the plant weighings and mensurations showed that, during the growing season, the main effect of water stress, mediated by the survival of fewer tillers and the premature senescence of leaves, was a reduction of leaf area (by 40%).

The effects of drought on barley growth: models and measurements showing the relative importance of leaf area and photosynthetic rate

1979 ◽  
Vol 92 (3) ◽  
pp. 703-716 ◽  
Author(s):  
B. J. Legg ◽  
W. Day ◽  
D. W. Lawlor ◽  
K. J. Parkinson
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Growth Models ◽  
Spring Barley ◽  
Stomatal Closure ◽  
Stomatal Resistance ◽  
Internal Resistance ◽  
Maximum Effect ◽  
Effects Of Drought ◽  
Intercepted Radiation

SUMMARYIn a field experiment on the effects of drought on spring barley the crop was protected from rain by automatic rain shelters. Various plots received irrigation at different times to give a range of drought treatments from full irrigation to no irrigation between emergence and harvest. The foliage area, light interception, stomatal resistance and leaf photosynthesis rate of five treatments were measured throughout the growing season, and a mathematical model has related the computed whole canopy photosynthesis to the measured total dry-matter yields at harvest. Hence, it was possible to estimate tha independent influences of drought on radiation interception, efficiency of use of intercepted radiation, and respiration. The analysis shows that for all treatments the decrease of intercepted radiation was the major factor in reducing yield, and it accounted for a loss of 30–40% for treatments that were stressed from the beginning of the season, and of 10–20% for treatments that were stressed after mid-May. Stomatal closure caused a reduction of up to 11% in daily photosynthesis, and the maximum effect was on plants that acquired a large leaf area before being stressed. However, the effect of stomatal closure integrated over the whole season was only 6% or less. Our measurements of internal resistance to carbon dioxide transfer were not precise enough to show significant differences between treatments; but increases of internal resistance, caused by stress, may have contributed to loss of yield.

Effects of water stress on leaf expansion, net photosynthesis, and vegetative growth of soybeans and cotton

1978 ◽  
Vol 56 (13) ◽  
pp. 1492-1498 ◽  
Author(s):  
James A. Bunce
Keyword(s):  
Water Vapor ◽  
Water Stress ◽  
Leaf Area ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Leaf Expansion ◽  
Soil Water Stress ◽  
Unit Leaf ◽  
Low Humidity ◽  
Net Assimilation

Soybeans and cotton were subjected to humidities from 40 to 80% at 23 °C and to soil drought during early vegetative growth under controlled conditions. Measurements were made of leaf water potentials, leaf expansion rates, leaf diffusive resistances to water vapor, and whole-shoot net photosynthesis rates. Net assimilation rates were calculated from harvest data. Low humidity resulted in low leaf water potential and low turgor in all cases and resulted in reduced leaf expansion rates in some, but not all, cases. Low humidity reduced dry weight growth only where leaf expansion rates were reduced. Net photosynthesis rates per unit leaf area were unaffected by low humidity, despite up to 1.5-fold increases in diffusive resistance to water vapor. During soil water stress, leaf expansion rates were reduced 1–2 days before net photosynthesis rates per unit leaf area were reduced, but leaf expansion continued at night after net photosynthesis rates were severely reduced by stress. As a result, the relative importance of leaf area expansion and net assimilation rate to growth in dry weight during soil water stress was dependent on the degree and duration of stress.

Seasonal patterns of net photosynthesis of loblolly pine from diverse origins

1986 ◽  
Vol 16 (5) ◽  
pp. 1063-1068 ◽  
Author(s):  
Brett A. Boltz ◽  
Bruce C. Bongarten ◽  
Robert O. Teskey
Keyword(s):  
Leaf Area ◽  
Loblolly Pine ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Seasonal Patterns ◽  
Strongly Correlated ◽  
Final Size ◽  
Unit Leaf Area ◽  
Late Season ◽  
Unit Leaf

Growth and photosynthesis were examined in seedlings of Pinustaeda L. (loblolly pine) from six widely separated provenances. The seasonal patterns of net photosynthesis were similar for each. Seedling net photosynthesis peaked in late October and net photosynthesis per unit leaf area peaked before midsummer and again in late October. When averaged over the entire season, seedling photosynthesis was greatest for Florida seedlings and least for Arkansas–Oklahoma and Texas seedlings. Seedling photosynthesis was strongly correlated with final size on all sampling dates and when averaged over the entire season. Both leaf area and net photosynthesis per unit leaf area contributed to the differences among provenances. Late season growth and photosynthesis, observed in the Florida provenance, increased provenance differences established early in the growing season.

Assimilate Movement in Lolium and Sorghum Leaves. I. Irradiance Effects on Photosynthesis, Export and the Distribution of Assimilates

1976 ◽  
Vol 3 (3) ◽  
pp. 377 ◽  
Author(s):  
IF Wardlaw
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Vascular System ◽  
Net Photosynthesis ◽  
Low Light ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Light Levels ◽  
C4 Grass ◽  
Reduced Light

At low light levels (20 W m-2 PAR), little difference was detectable in net photosynthetic rates between leaves of the C3 grass Lolium temulentum and the C4 grass Sorghum sudanense. At low light, both species also had similar rates of export of photosynthate per unit leaf area, although the rate of export of 14C, following the assimilation of 14CO2 by the uppermost fully expanded leaf, was much greater in Sorghum. As light levels were increased to 96 W m-2 PAR or greater, net photosynthesis rose more in Sorghum than in Lolium and a greater proportion of the assimilate was exported from the Sorghum leaf, while Lolium with the thicker leaf showed a much greater capacity for storage of photosynthate. High and low light pretreatments, which altered the amount of both soluble and insoluble dry matter in the leaf, had little effect on the percentage rate of export of 14C following the uptake of 14CO2, which suggests that the bulk of the stored material may be effectively separated from the pathway of transfer from the chloroplast to the vascular system within the leaf. The pattern of distribution of 14C-labelled assimilates to other parts of the plant was only slightly affected by reduced light during the 4-h translocation period' however, a 3-day pretreatment at low light significantly reduced the proportion of the assimilates moving to the roots.

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

INFLUENCE OF PHOTOPERIOD AND WATER STRESS ON GROWTH, YIELD AND DEVELOPMENT RATE OF BARLEY MEASURED IN HEAT UNITS

1987 ◽  
Vol 67 (1) ◽  
pp. 21-34 ◽  
Author(s):  
L. M. DWYER ◽  
D. W. STEWART
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Dry Matter ◽  
Growth Yield ◽  
Development Rate ◽  
Degree Days ◽  
Heat Units ◽  
Matter Production ◽  
Stress Maximum ◽  
Significant Yield

Barley (Hordeum vulgare ’Bruce’) was grown in a greenhouse under three photoperiods (8, 12 and 16 h) and nine watering treatments, resulting in different timing, duration and intensity of water stress. Phenological development, according to the Feekes scale, was monitored three times a week and leaf area was measured weekly from tillering to ripening. Final aboveground and root dry matter production and grain yield were obtained at harvest. Phenological observations were fit to a nonlinear photothermal model that expressed phenological development as a function of heat units modified by photoperiod. In the absence of water stress, maximum leaf area was directly proportional to photoperiod and the time of maximum leaf area was delayed at longer photoperiods. Water stress hastened leaf area senescence and, in general, the more severe the stress, the greater the reduction in leaf area. Most stress treatments also resulted in lower shoot/root ratios than found in well-watered controls, as well as significant yield reductions. Reduction in biomass and yield components appeared independent of photoperiod. In contrast, not only was phenological development rate proportional to photoperiod, but the effect of water stress on development rate was modified by photoperiod. Development was significantly delayed by several water stress treatments; no treatment significantly hastened development. A stress period from tillering to the beginning of stem extension caused the largest, and most consistent, delay and the duration of the delay was inversely proportional to the photoperiod.Key words: Barley, degree days, phenology, leaf area, biomass

Radiation and water balance properties of cadmium-polluted maize in a wet year

2012 ◽  
Vol 60 (3) ◽  
pp. 191-200 ◽  
Author(s):  
A. Anda
Keyword(s):  
Leaf Area ◽  
Dry Matter ◽  
Sensible Heat ◽  
Net Radiation ◽  
Yield Losses ◽  
Vegetative Organs ◽  
Unit Leaf ◽  
Silage Maize ◽  
Matter Production ◽  
Annual Water

The effect of spraying maize weekly with a 0.5 M concentration of Cd was studied in Hungary at two water supply levels. Cd reduced the size of the leaf area and the annual water loss. The intensity of evapotranspiration (mm water/unit leaf area) of the polluted crops grew. The higher net radiation of polluted maize resulted in an increase in sensible heat and a warmer canopy. The warmer the canopy, the higher the stress level of the contaminated crops was. While Cd caused a 28% significant decline in plant dry matter production in the rainfed plots, only a declining tendency amounting to a few percent was recorded in the ET treatment.Cd of atmospheric origin was only detected in the leaves; it was not accumulated in the grain. It was concluded from the results that the yield losses in grain maize grown on Cd-polluted areas could be mitigated by irrigation. The production of silage maize, however, is not recommended in regions affected by Cd pollution, especially in areas where irrigation is required, since supplementary water supplies promote the accumulation of Cd in the vegetative organs.

Effects of drought on leaf area development, biomass production and nitrogen uptake of durum wheat grown in a Mediterranean environment

1995 ◽  
Vol 46 (1) ◽  
pp. 99 ◽  
Author(s):  
F Giunta ◽  
R Motzo ◽  
M Deidda
Keyword(s):  
Durum Wheat ◽  
Leaf Area ◽  
Nitrogen Uptake ◽  
Dry Matter ◽  
Growing Season ◽  
Dry Matter Accumulation ◽  
Mediterranean Environment ◽  
Area Index ◽  
Area Development ◽  
Leaf Area Development

A field experiment was carried out in Sardinia (Italy) on durum wheat to analyse the effects of different moisture treatments, irrigated (I), rainfed (R) and stressed (S), on leaf area index (LAI), radiation intercepted (Q) and water use (WU), efficiency of conversion of radiation and water into dry matter (RUE and WUE), nitrogen uptake and carbon and nitrogen partitioning in the above-ground part of the plant. In the period between beginning of stem elongation and heading, drought affected the maximum LA1 in the most stressed treatment (4.7 in S v. about 6.9 in R and I), but not Q and WU. RUE was also lowered by drought in this period (0.68 in S v. about 0.95 g MJ-1 in R and I) as a reduced biomass was recorded in S at heading (528gm-2 in S v. 777 g m-2 on average in R and I). In contrast with the previous period, the reduction in LA1 between heading and maximum ear weight (MEW) determined a significant reduction in Q and WU, WUE and RUE, resulting, ultimately, in notable differences in the total biomass produced until MEW (1203, 930 and 546 gm-2 in I, R and S respectively). The amount of stem reserves relocated to the grain decreased as the level of stress increased, going from 223gm-2 in I to 9gm-2 in S and was accumulated almost entirely (from 76% of the total in I to 100% in S), in the post-heading period. Nitrogen percentage was not affected by the treatments applied apart from the higher values in stem and flag leaf in S later in the growing season due to an inhibition of nitrogen translocation in S. The total nitrogen uptake was lower in S (12.3gm-2) than in I (16.6gm-2) only as a consequence of the different dry matter accumulation patterns. The importance of WUE in this type of Mediterranean environment is discussed, with particular concern to the key role of modulation of leaf area development through the growing season.

Growth of spring barley under drought: crop development, photosynthesis, dry-matter accumulation and nutrient content

1981 ◽  
Vol 96 (1) ◽  
pp. 167-186 ◽  
Author(s):  
D. W. Lawlor ◽  
W. Day ◽  
A. E. Johnston ◽  
B. J. Legg ◽  
K. J. Parkinson
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Dry Matter ◽  
Spring Barley ◽  
Grain Filling ◽  
Dry Matter Accumulation ◽  
Area Index ◽  
Water Deficits ◽  
Maximum Value ◽  
Grain Filling Period

SUMMARYThe effects of water deficit on growth of spring barley were analysed under five irrigation treatments. One crop was irrigated at weekly intervals from emergence throughout the growing season, and one was not irrigated at all after emergence. Soil water deficits in the other treatments were allowed to develop early, intermediate or late in the crop's development.Weekly irrigation produced a crop with a large leaf area index (maximum value 4) and maintained green leaf and awns throughout the grain-filling period. Early drought decreased leaf area index (maximum value 2) by slowing expansion of main-stem leaves and decreasing the number and growth of tiller leaves. Leaf senescence was also increased with drought. Drought late in the development of ears and leaves and during the grain-filling period caused leaves and awns to senesce so that the total photosynthetic areas decreased faster than with irrigation. Photosynthetic rate per unit leaf area was little affected by drought so total dry-matter production was most affected by differences in leaf area.Early drought gave fewer tillers (550/m2) and fewer grains per ear (18) than did irrigation (760 tillers/m2 and 21 grains per ear). Late irrigation after drought increased the number of grains per ear slightly but not the number of ears/m2. Thus at the start of the grain-filling period crops which had suffered drought early had fewer grains than irrigated (9·5 and 18·8 × 103/m2 respectively) or crops which suffered drought later in development (14 × 103/m2).During the first 2 weeks of filling, grains grew at almost the same rate in all treatments. Current assimilate supply was probably insufficient to provide this growth in crops which had suffered drought, and stem reserves were mobilized, as shown by the decrease in stem mass during the period. Grains filled for 8 days longer with irrigation and were heavier (36–38 mg) than without irrigation (29–30 mg). Drought throughout the grainfilling period after irrigation earlier in the season resulted in the smallest grains (29 mg).Grain yield depended on the number of ears, the number of grains per ear and mass per grain. Early drought decreased tillering and tiller ear production and the number of grains that filled in each ear. Late drought affected grain size via the effects on photosynthetic surface area.Drought decreased the concentrations of phosphorus, potassium and magnesium in the dry matter of crops, and irrigation after drought increased them. Concentration of nitrogen was little affected by treatment. Possible mechanisms by which water deficits and nutrient supply affect crop growth and yield are discussed.

scholarly journals Growth Analysis and Photosynthesis Measurements of Cucumber Seedlings Grown under Light with Different Red to Far-red Ratios

HortScience ◽  
2016 ◽  
Vol 51 (7) ◽  
pp. 843-846 ◽  
Author(s):  
Toshio Shibuya ◽  
Ryosuke Endo ◽  
Yoshiaki Kitaya ◽  
Saki Hayashi
Keyword(s):  
Leaf Area ◽  
Growth Parameters ◽  
Weight Ratio ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Unit Leaf Area ◽  
Cucumber Seedlings ◽  
Unit Leaf ◽  
Net Assimilation ◽  
Normal Light

Light with a higher red to far-red ratio (R:FR) than sunlight reduces plant growth, but the cause has not been firmly established. In the present study, cucumber seedlings were grown under normal light (similar to sunlight; R:FR = 1.4) from metal-halide lamps or high-R:FR light (R:FR = 4.3) created by transmitting their light through FR-absorbing film, and then their growth parameters and photosynthesis were compared. The relative growth rate (RGR) at high R:FR was 92% of that under normal R:FR, although the net assimilation rate (NAR) did not differ between the treatments, indicating that changes in net photosynthesis per unit leaf area did not cause the growth inhibition at high R:FR. The CO2 exchange per unit leaf area did not differ between the treatments, which supports this hypothesis. The leaf area ratio (LAR) of total plant dry weight of high R:FR seedlings to that of normal R:FR seedlings was also 92%. This suggests that growth suppression in the high R:FR seedlings was caused mainly by decreased LAR. The specific leaf area (SLA) and leaf weight ratio (LWR), components of LAR, under high-R:FR light were 89% and 105%, respectively, of those under normal light, indicating that the smaller LAR at high R:FR mainly results from suppressed leaf enlargement per unit leaf dry matter.

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