Whole-Plant Carbon Balance During Osmotic Adjustment to Drought and Salinity Stress

1986 ◽  
Vol 13 (1) ◽  
pp. 33 ◽  
Author(s):  
KJ Mccree
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Osmotic Adjustment ◽  
Carbon Balance ◽  
Crop Production ◽  
Metabolic Cost ◽  
Co2 Exchange ◽  
Unit Leaf ◽  
Whole Plant ◽  
The Cost

The whole-plant daily carbon balance (the 24-h sum of photosynthetic input of substrate carbon per plant and loss of carbon through respiration) is the CO2 exchange measure that relates most closely to crop production rates. Water stress reduces the photosynthetic input, reducing both leaf area and photosynthetic rate per unit leaf area. Respiratory losses are reduced more or less proportionately. A less-than-proportional loss was observed during osmotic adjustment in sorghum (Sorghum bicolor (L) Moench): the metabolic cost of storing photosynthate and using it for osmotic adjustment was less than the cost of converting it to new biomass. A slightly increased metabolic cost is often found under salt stress but, in sorghum plants that were salinized and then water stressed, the adverse effects of salt were mitigated by decreased water loss rates and enhanced osmotic adjustment during water stress. More tests involving combined salt and water stress are needed.

Growth and yield of sorghum lines extracted from a population for differences in osmotic adjustment

1995 ◽  
Vol 46 (1) ◽  
pp. 61 ◽  
Author(s):  
T Tangpremsri ◽  
S Fukai ◽  
KS Fischer
Keyword(s):  
Water Stress ◽  
Grain Yield ◽  
Leaf Area ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Dry Matter ◽  
Grain Filling ◽  
Grain Number ◽  
Glasshouse Experiment ◽  
The Difference

From 47 S2 lines which had been extracted from a random mated population of sorghum, eight lines for a glasshouse experiment and four lines for a field experiment were divergently selected for variation in osmotic adjustment, and were grouped into two, High and Low osmotic adjustment (OA). Both the glasshouse and field experiments examined whether osmotic adjustment modified the plants' response to soil water deficit and also whether grain sink demand for assimilates, varied by removal of 50% spikelets, affected osmotic adjustment. In each experiment, there were well-watered control and water stress treatments. In both experiments, the dawn osmotic potential in the High OA group was always lower than in the Low OA group under water limiting conditions, and the difference was significant after anthesis. The difference in osmotic potential was about 0.1 MPa in the field and up to 0.25 MPa in the glasshouse. In the glasshouse experiment, removal of 50% spikelets at anthesis significantly decreased osmotic potential during grain filling, suggesting that osmotic adjustment is influenced by the availability of assimilates in the leaves. Under well-watered conditions, the two groups behaved very similarly in terms of maximum leaf area, green leaf area retention during grain filling, total dry matter production, grain yield and grain number in both experiments. Under water-limiting conditions, the High OA group produced larger maximum leaf area and had better leaf retention during grain filling. Despite similar water use, total dry matter was also significantly higher in the High OA group though the difference was small. Grain number was also greater in this group in both experiments, whereas grain yield was significantly higher in the High OA group in the field, but not in the glasshouse where severe water stress developed more rapidly. It is concluded that the adverse effect of water stress can be reduced by adopting sorghum genotypes with high osmotic adjustment. However, selection for high osmotic adjustment needs to ensure that osmotic adjustment is not solely due to small head size.

Landforming a red-brown earth dash effects of topsoil removal and redistribution on irrigated crop production

1988 ◽  
Vol 28 (5) ◽  
pp. 599 ◽  
Author(s):  
KE Pritchard ◽  
WK Mason ◽  
SP Byrne
Keyword(s):  
Crop Production ◽  
Yield Potential ◽  
Zn Deficiency ◽  
Yield Increase ◽  
Whole Plant ◽  
Cumulative Production ◽  
Normal Soil ◽  
Topsoil Removal ◽  
Soil Zn ◽  
The Cost

Landforming is the use of earthmoving machinery and laser controlled land planes to improve the efficiency of irrigation layouts. Duplex soils with shallow A horizons are vulnerable to the exposure of subsoil in this process, and production from areas where topsoil has been removed is substantially less than from normal soil. A landformed area with a large range of depths of cut (soil removed) and fill (extra soil deposited) gave a linear decrease in dry matter (DM) yield/ha of maize (Zea mays) from 23.7 to 11.2 t/ha, and of oats (Avena sativa) from 13.9 to 7.5 t/ha with increasing depths of topsoil removal, but no progressive yield increase with added soil, so that overall production was estimated to be decreased by 16%. Whole plant N concentration was 24% lower, plant Zn 33% lower and soil Zn 43% lower from areas where topsoil was removed. Ameliorating the exposed subsoil with ripping, gypsum and compensatory N and P fertiliser produced only 71% of maize DM compared with normal soil (16.5 v. 11.7 t/ha). However, the replacement of 75 mm of topsoil completely restored yield. In a pot experiment which removed many of the physical limitations of the field, maize yields from subsoil and topsoil were similar when Zn was added to the subsoil in addition to N, P and K. Although Zn deficiency can limit maize growth on exposed subsoil, soil physical characteristics are a major cause of reduced yield and these were not eliminated in the field by amelioration. The cost of topsoil replacement during landforming may be less, in the long term, than amelioration plus cumulative production losses. The importance of topsoil in maintaining the yield potential of cropping land should not be underestimated in landforming designs for irrigation.

The Growth of Banana Plants in Relation to Temperature

1983 ◽  
Vol 10 (1) ◽  
pp. 43 ◽  
Author(s):  
DW Turner ◽  
E Lahav
Keyword(s):  
Water Content ◽  
Leaf Area ◽  
High Temperatures ◽  
Relative Water Content ◽  
Chilling Injury ◽  
Vapour Pressure Deficit ◽  
Dry Weight ◽  
Unit Leaf ◽  
Whole Plant ◽  
Relative Water

Bananas (cv. Williams) were grown for 12 weeks in sunlit growth chambers at day/night temperatures of 17/10, 21/14, 25/18, 29/22, 33/26 or 37/30°C. Humidity was not controlled. At 17/10°C, the plants showed chilling injury and heat injury occurred at 37/30°C. Total plant dry weight was greatest at 25/18°C while leaf area was greatest at 33/26°C. At high temperatures proportionately less dry matter was present in the roots and corm compared with plants at 25/18°C. High temperatures produced more horizontal leaves but, to compensate for this, the laminae folded more readily. Lamina folding was closely associated with relative water content of the laminae, except under cool conditions where laminae folded despite high (97-99%) leaf relative water contents. Unit leaf rate (increase in whole plant dry weight per unit leaf area per unit time) was greatest at 21/14°C (5.8 g m-2 day-1) and least at 37/30°C (1.7 g m-2 day-1.) and had a strong negative association with whole-plant leaf resistance. Leaf relative water content was more closely associated with vapour pressure deficit than temperature and even at 37/30°C was high at 94%.

Relationships between biomass allocation, axis organogenesis and organ expansion under shading and water deficit conditions in grapevine

2015 ◽  
Vol 42 (12) ◽  
pp. 1116 ◽  
Author(s):  
Benoît Pallas ◽  
Angélique Christophe
Keyword(s):  
Water Stress ◽  
Plant Growth ◽  
Leaf Area ◽  
Water Deficit ◽  
Biomass Allocation ◽  
Abiotic Stresses ◽  
Sink Strength ◽  
Secondary Axis ◽  
Whole Plant ◽  
Abiotic Constraints

The relationships between whole-plant growth and morphogenetic processes under abiotic stresses are still partly unknown. Whole-plant biomass growth can be decreased by many abiotic stresses, including water deficit and shading. Two experiments were performed on potted plants of one grapevine cultivar (Vitis vinifera L. cv. Syrah) subjected to watering and shading treatments. Under water stress, plants reduced their primary and secondary axis leaf production rate, whereas secondary axis budburst was relatively unaffected. Individual leaf area was reduced and a strong decrease in leaf expansion rate was observed. Under shading, primary axis organogenesis was maintained, both secondary axis budburst rate and phytomer appearance rate were decreased, and individual leaf area slightly increased. Specific leaf area did not change under soil water deficit, whereas it increased under shading. These results confirm the existence of dynamic changes in organ sink strength and biomass allocation patterns to favour plant leaf area growth under shading, and to reduce plant leaf area and water losses by transpiration under water stress. From a modelling point of view, this study shows that functional structural models based on a C balance are not fully relevant for simulating plant growth under abiotic constraints if they do not include non-trophic relationships (hormonal signalling or plant hydraulic properties) that modify organ sink strength according to abiotic constraints.

FIELD EVALUATION OF GROWTH AND NITROGEN FIXATION IN PEAS SELECTED FOR HIGH AND LOW PHOTOSYNTHETIC CO2 EXCHANGE

1982 ◽  
Vol 62 (1) ◽  
pp. 5-17 ◽  
Author(s):  
J. D. MAHON
Keyword(s):  
Leaf Area ◽  
Field Measurements ◽  
Field Evaluation ◽  
Co2 Exchange ◽  
Physiological Age ◽  
Area Index ◽  
Large Variability ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Area Basis

Six genotypes of pea (Pisum sativum L.), selected for either high or low CO2 exchange rate per unit leaf area (CER) on the basis of field measurements, were grown in field plots during 1978 and 1979. During two growing seasons, CER was determined in leaves of different physiological age at several times of the day and season. Dry weights, leaf areas and node numbers were determined 4, 7 and 10 wk after planting, and again after pod ripening. C2H2 reduction by detached roots was measured 5, 6, 8 and 9 wk after planting. Despite the large variability in CER with years, leaf numbers, and times of measurement, the mean CER of the three genotypes selected for high rates was always greater than that of the low selected group. CER was significantly correlated with growth per unit leaf area (E) and the high to low group ratios averaged 1.4 for CER and 1.3 for E. C2H2 reduction on an equivalent leaf area basis was not different in the two groups. On a land area basis, the low CER group had a significantly greater leaf area index which compensated for the decreased CER, and estimates of total CO2 exchange, growth and C2H2 reduction were similar in the two groups. Total aboveground dry matter and seed yields were greater in the low CER group, but harvest index was generally greater in those genotypes selected for high CER.

Carbon Production of Sunflower Cultivars in Field and Controlled Environment. II. Leaf Growth

1980 ◽  
Vol 7 (5) ◽  
pp. 575 ◽  
Author(s):  
HM Rawson ◽  
GA Constable ◽  
GN Howe
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Leaf Growth ◽  
Field Studies ◽  
Leaf Number ◽  
Area Index ◽  
Average Growth ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Stomatal Apparatus

In field studies of several cultivars of sunflower grown on stored soil moisture or with irrigation, yield was positively related to leaf area at anthesis. The regression which described this relationship stated that 1370 kg seed ha-1 were associated with a unit increment in leaf area index. Cultivars differed in final leaf number, rate of leaf appearance, and in the vertical distribution of leaf area in the profiles. Final leaf number of plants grown on stored moisture remained the same as in irrigated plants, but the period for which each leaf grew was reduced from 19 to 16 days while the average growth rate was reduced from 13 to 6 cm2 day-1. These changes reduced the final leaf area from 5700 to 1900 cm2 per plant. As water stress increased, the period when leaves grew fastest became progressively earlier, from approximately 35% Amax to when leaves were less than 5 cm2. Water stress increased stomatal frequencies but reduced the area of individual stomata so that the area of the stomatal apparatus per unit leaf area was unchanged. This may partially explain the constancy of peak gas exchange per unit leaf area of sunflower grown under different water regimes. There was evidence that leaves could recommence growth when the stress was alleviated.

scholarly journals Why are tropical conifers disadvantaged in fertile soils? Comparison of Podocarpus guatemalensis with an angiosperm pioneer, Ficus insipida

2020 ◽  
Vol 40 (6) ◽  
pp. 810-821 ◽  
Author(s):  
Ana C Palma ◽  
Klaus Winter ◽  
Jorge Aranda ◽  
James W Dalling ◽  
Alexander W Cheesman ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Leaf Area ◽  
Nitrogen Availability ◽  
Dry Mass ◽  
Area Ratio ◽  
Leaf Area Ratio ◽  
Unit Leaf Area ◽  
Unit Leaf ◽  
Fertilized Soil ◽  
Whole Plant

Abstract Conifers are, for the most part, competitively excluded from tropical rainforests by angiosperms. Where they do occur, conifers often occupy sites that are relatively infertile. To gain insight into the physiological mechanisms by which angiosperms outcompete conifers in more productive sites, we grew seedlings of a tropical conifer (Podocarpus guatemalensis Standley) and an angiosperm pioneer (Ficus insipida Willd.) with and without added nutrients, supplied in the form of a slow-release fertilizer. At the conclusion of the experiment, the dry mass of P. guatemalensis seedlings in fertilized soil was approximately twofold larger than that of seedlings in unfertilized soil; on the other hand, the dry mass of F. insipida seedlings in fertilized soil was ~20-fold larger than seedlings in unfertilized soil. The higher relative growth rate of F. insipida was associated with a larger leaf area ratio and a higher photosynthetic rate per unit leaf area. Higher overall photosynthetic rates in F. insipida were associated with an approximately fivefold larger stomatal conductance than in P. guatemalensis. We surmise that a higher whole-plant hydraulic conductance in the vessel bearing angiosperm F. insipida enabled higher leaf area ratio and higher stomatal conductance per unit leaf area than in the tracheid bearing P. guatemalensis, which enabled F. insipida to capitalize on increased photosynthetic capacity driven by higher nitrogen availability in fertilized soil.

scholarly journals Influence of Water Stress on Grapevines Growing in the Field: From Leaf to Whole-Plant Response

1993 ◽  
Vol 20 (2) ◽  
pp. 143 ◽  
Author(s):  
T Winkel ◽  
S Rambal
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Water Status ◽  
Stomatal Closure ◽  
Indirect Evidence ◽  
Hydraulic Conductance ◽  
Water Vapour Pressure ◽  
Vitis Vinifera L ◽  
Plant Water ◽  
Whole Plant

A comparative study of soil-plant water relations was conducted on three grapevine cultivars (Vitis vinifera L. cvv. carignane, merlot, shiraz) to investigate their adjustment to short-term and long-term water stress under field conditions. Adjustment was a function of the relative stability of the internal plant water status on diurnal and seasonal scales. On a diurnal scale, stomatal closure in response to water vapour pressure directly contributed to this stability. Indirect evidence suggested an influence of the soil water status on the diurnal stomatal activity. On a seasonal scale, sufficient leaf hydration required high whole-plant hydraulic conductance. This was achieved by either daily stomatal regulation or limitation of leaf area. Physiological adjustment to water stress through stomatal control was well developed in cv. carignane, which originated in a Mediterranean environment. However, cv. shiraz, which was of mesic origin, apparently adjusted to water stress by reducing leaf area. Our study demonstrates the utility of integrating data on stomatal conductance, leaf water potential and whole-plant hydraulic conductance to interpret whole plant adaptation to water stress, and elucidates two mechanisms by which genotypes differentially acclimate to water stress.

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.

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