Control of Leaf Expansion in Wheat Seedlings Growing in Drying Soil

1990 ◽  
Vol 17 (2) ◽  
pp. 149 ◽  
Author(s):  
JB Passioura ◽  
A Gardner
Keyword(s):  
Water Status ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Evaporative Demand ◽  
Wheat Seedlings ◽  
Leaf Expansion Rate

The relative leaf expansion rate (RLER) of plants in drying soil eventually falls behind that of well watered plants. There is increasing evidence that the roots sense the drying of the soil and send signals to the leaves that control their behaviour independently of any effects of the soil's drying on the water status of the leaves. The roots could be sensing the falling availability of phosphorus, the falling water status, or the hardening of the soil. This paper explores these possibilities and concludes that, in the soil used, the roots were sensing both the water status and the strength of the soil but not the availability of phosphorus. Some of the experiments were done with a high evaporative demand on the leaves to see if the RLER would then be sensitive to the leaves' water status; it was not.

Root Signals Control Leaf Expansion in Wheat Seedlings Growing in Drying Soil

1988 ◽  
Vol 15 (5) ◽  
pp. 687 ◽  
Author(s):  
JB Passioura
Keyword(s):  
Water Potential ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Wheat Seedlings ◽  
Pneumatic Pressure ◽  
Root Signals ◽  
Leaf Expansion Rate

Wheat plants were grown with their roots and soil in pressure chambers, so that the leaves could be kept highly turgid, even when the soil dried, by applying a pneumatic pressure to the roots. The relative leaf expansion rate (RLER) of plants in drying soil eventually fell behind that of well-watered plants, but, remarkably, the fall in RLER was the same whether or not the leaves were kept highly turgid. It is argued that the roots sensed the drying of the soil and sent signals to the leaves that controlled their behaviour, overriding any effects of turgor on the leaves. It is likely that the roots were sensing not only the water potential of the soil but also its hardness, which increased substantially as the soil dried.

Misting of Tomato Plants Improves Leaf Water Status but not Leaf Growth

1997 ◽  
Vol 24 (1) ◽  
pp. 9 ◽  
Author(s):  
R. J. Stirzaker ◽  
P. T. Hayman ◽  
B. G. Sutton
Keyword(s):  
Vegetative Growth ◽  
Root Zone ◽  
Leaf Growth ◽  
Water Status ◽  
Leaf Expansion ◽  
Leaf Water ◽  
Expansion Rate ◽  
Control Treatment ◽  
Leaf Water Status ◽  
Leaf Expansion Rate

Field and laboratory experiments were carried out to determine whether modification of the aerial environment in a hot climate would improve the leaf growth rate and ultimately the yield of well- irrigated processing tomatoes, Lycopersicon esculentum Mill. cv. UC82B. In the field, the transpiration rate was modified by frequent applications of a fine mist. Misting reduced the diurnal fall in leaf water potential by up to 0.5 MPa, but had no effect on weekly vegetative growth or fruit yield, compared to a control treatment which was not misted but had accurately managed drip irrigation. To investigate these processes further, we studied the relationship between leaf water status and leaf growth in the laboratory using equipment in which a pot is placed inside a pressure chamber, with the leaves enclosed in a cuvette. Immediately following a misting event, both the hydrostatic pressure of the leaf xylem and the leaf expansion rate increased. The increase in leaf expansion rate was sustained for about 10 min and then fell below the pre-misted rate so that the net effect of a misting event on leaf expansion was small or nil. When an elevated leaf water status was sustained by pressurising the soil for over an hour, there was only a transient increase in leaf growth, and leaf growth stopped after the pressure was removed. Both in the laboratory and field, the overall leaf or vegetative growth was not sensitive to rapid fluctuations in leaf water status. The implication is that, if sufficient attention is paid to managing the root zone of crops, the more expensive and less efficient modification of the shoot environment is unnecessary.

scholarly journals Paclobutrazol Influences Salinity Responses of Peach and Olive

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 898B-898
Author(s):  
A. Abu El-Kashab ◽  
A.F. El-Sammak ◽  
A.A. Elaidy ◽  
M.l. Salama ◽  
M. Rieger
Keyword(s):  
Salt Stress ◽  
Prunus Persica ◽  
Foliar Application ◽  
Dry Weight ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Salt Tolerant ◽  
Salinity Response ◽  
Old Trees ◽  
Leaf Expansion Rate

We studied the effect of a 200-mg·liter–1 foliar application of paclobutrazol (PBZ) on growth and physiological responses of Prunus persica `Nemaguard' (salt-sensitive) and Olea europea `Manzanillo' (salt-tolerant) to salt stress. One-year-old trees were grown in 3 sand: 3 field soil: 4 pine bark media in 20-cm pots in a greenhouse and were irrigated with nutrient solutions adjusted with 0, 9, 18, or 36 mmol NaCl for peach and 0, 36, 72, 108 mmol NaCI for olive. Dry weight, photosynthesis, and leaf conductance decreased with increasing salinity for both species. However, leaf expansion rate was unaffected by NaCl. PBZ reduced dry weight for peach only, but PBZ increased photosynthesis and reduced leaf expansion rate for both species. Relative water content was decreased by salt but increased by PBZ. PBZ reduced the foliar Na and Cl content in peach but not olive. Olive had less Na in leaves than peach at 36 mmol NaCI, accumulated less C in leaves in all salt treatments, and had higher foliar Na without symptom expression. PBZ may reduce salt stress in sensitive species like peach by reducing foliar Na and Cl accumulation but has less influence on the salinity response of the more salt-tolerant olive.

scholarly journals Maximum area, expansion rate and duration of summer rape leaves

1992 ◽  
Vol 72 (1) ◽  
pp. 117-126 ◽  
Author(s):  
M. J. Morrison ◽  
D. W. Stewart ◽  
P. B. E. McVetty
Keyword(s):  
Brassica Napus ◽  
Leaf Area ◽  
Air Temperature ◽  
Ambient Air ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Regression Equations ◽  
Leaf Position ◽  
Leaf Area Duration ◽  
Leaf Expansion Rate

The vegetative development phase in summer rape (Brassica napus) is characterized by the appearance and expansion of leaves. The objectives of this research were to examine the maximum individual leaf area (LAmax), leaf expansion rate (LAX) and leaf area duration (LAD) of individual leaves as influenced by leaf position and ambient air temperature. Westar summer rape was grown from seed to maturity in controlled environment chambers set at temperatures ranging from 10 to 25 °C. Plants representing each stage of leaf development were selected at random from the population for leaf area determination. Logistic equations were used to relate the area of individual leaves to Growing Degree Days (GDD). Polynomial regression equations were used to fit curves describing the relationship between LAmax, LAX, LAD and leaf position or air temperature. As the air temperature increased the LAmax increased. LAX increased to a maximum which occurred when LAmax was at its maximum. There were no significant differences for LAX among air temperatures ranging from 13.5 to 22 °C. Mean LAX was 0.21 cm2 GDD−1. There were no significant differences in LAD due to leaf position or air temperature. Mean LAD was 140.1 GDD.Key words: Leaf area, leaf expansion rate, leaf area duration, Brassica napus

scholarly journals Leaf expansion rate and life span of floating leaves in Victoria amazonica (Poepp.) Sowerby growing in Kebun Raya, Bogor, Indonesia.

Tropics ◽  
2006 ◽  
Vol 15 (4) ◽  
pp. 429-433 ◽  
Author(s):  
Hidenobu KUNII ◽  
Senny SUNANISARI ◽  
Haruo FUKUHARA ◽  
Takuo NAKAJIMA ◽  
Fifi WIDJAJA
Keyword(s):  
Life Span ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Floating Leaves ◽  
Leaf Expansion Rate

scholarly journals Relative leaf expansion rate and other leaf-related indicators for detection of drought stress in chili pepper (Capsicum annuum L.).

2017 ◽  
Vol 11 (12) ◽  
pp. 1617-1625 ◽  
Author(s):  
Laily Ilman Widuri ◽  
◽  
Benyamin Lakitan ◽  
Mery Hasmeda ◽  
Erizal Sodikin ◽  
...  
Keyword(s):  
Drought Stress ◽  
Capsicum Annuum ◽  
Leaf Expansion ◽  
Chili Pepper ◽  
Expansion Rate ◽  
Capsicum Annuum L ◽  
Leaf Expansion Rate

scholarly journals Role of proline and leaf expansion rate in the recovery of stressed white clover leaves with increased phosphorus concentration

2000 ◽  
Vol 146 (2) ◽  
pp. 261-269 ◽  
Author(s):  
DHANANJAY K. SINGH ◽  
PETER W. G. SALE ◽  
CHARLES K. PALLAGHY ◽  
VIJAYA SINGH
Keyword(s):  
White Clover ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Phosphorus Concentration ◽  
Leaf Expansion Rate

Effects of long-term and short-term supply of NO3− or NH4+ on Cytokinin levels and leaf expansion rate in tomato (Lycopersicon esculentum L. cv. Moneymaker)

2001 ◽  
pp. 134-135
Author(s):  
Y. S. Rahayu ◽  
P. Walch-Liu ◽  
G. Neumann ◽  
N. v. Wirén ◽  
V. Römheld ◽  
...  
Keyword(s):  
Lycopersicon Esculentum ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Short Term ◽  
Leaf Expansion Rate

Hydraulic and chemical signals in the control of leaf expansion and stomatal conductance in soybean exposed to drought stress

2003 ◽  
Vol 30 (1) ◽  
pp. 65 ◽  
Author(s):  
Fulai Liu ◽  
Christian Richardt Jensen ◽  
Mathias Neumann Andersen
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Soil Water ◽  
Leaf Growth ◽  
Chemical Signals ◽  
Leaf Expansion ◽  
Expansion Rate ◽  
Biophysical Parameters ◽  
Water Deficits ◽  
Leaf Expansion Rate

Both hydraulic and chemical signals are probably important in regulating leaf growth and stomatal conductance of soybean (Glycine max L. Merr.) under drought stress. However, until now they have not been investigated concomitantly in this species. To explore this, a pot experiment in a temperature-regulated greenhouse was conducted, in which plants were subjected to progressive drought during early reproductive stages. Biophysical parameters, viz. relative leaf expansion rate, stomatal conductance, leaf turgor, leaf [ABA], xylem pH and xylem [ABA] were followed in control and stressed plants. Drought stress decreased relative leaf expansion rate, stomatal conductance and leaf turgor, whereas it increased leaf [ABA], xylem pH and xylem [ABA]. As soil dried, significant differences between water treatments for relative leaf expansion rate, stomatal conductance, leaf turgor, leaf [ABA], xylem pH and xylem [ABA] were observed at 14, 9, 14, 14, 14 and 9 d after imposition of stress, respectively. The relationships of relative values for relative leaf expansion rate, stomatal conductance, leaf turgor, leaf [ABA] and xylem pH to the fraction of transpirable soil water (FTSW) were well described by linear-plateau functions that allowed calculation of the soil-water thresholds at which processes in stressed plants began to diverge from well-watered controls. The soil-water threshold for stomatal conductance (0.64) was significantly higher than that for relative leaf expansion rate (0.29), xylem pH (0.28), leaf [ABA] (0.27) and leaf turgor (0.25). Relative xylem [ABA] increased, first linearly (when FTSW > 0.5) and then exponentially (when FTSW < 0.5) with decreasing FTSW. Relative stomatal conductance decreased exponentially with increasing relative xylem [ABA] (r2=0.98). Decreased stomatal conductance coincided with an increase in xylem [ABA] and occurred before any significant change of leaf turgor could be detected, indicating that chemical signals (seemingly root-originated ABA) control stomatal behaviour at moderate soil water deficits. Relative relative leaf expansion rate was linearly correlated with relative leaf turgor (r2=0.93), relative xylem pH (r2=0.97) and relative leaf [ABA] (r2=0.98), implying that both hydraulic and chemical signals were probably involved in regulation of leaf expansion at severe soil water deficits.

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