Water relations of white clover (Trifolium repens L.) in a drying soil, as a function of phosphorus supply and defoliation frequency

1997 ◽  
Vol 48 (5) ◽  
pp. 675 ◽  
Author(s):  
DhananJay K. Singh ◽  
Peter W. G. Sale ◽  
Blair M. McKenzie
Keyword(s):  
Water Stress ◽  
White Clover ◽  
Stress Symptoms ◽  
Heavy Grazing ◽  
Water Stress Condition ◽  
Evapotranspiration Rate ◽  
Dry Soil ◽  
Defoliation Frequency ◽  
Rate Of Decline ◽  
P Supply

A glasshouse pot experiment was carried out to determine how white clover plants responded to repeated drying cycles, under conditions of varying P supply and defoliation frequency. Measurements included leaf water potential (Ψleaf), evapotranspiration rate, soil matric potential (Ψsoil), an assessment of visual water stress symptoms, and the rate of plant recovery on rewatering. The rate of decline in Ψleaf per unit decline in Ψsoil was greater in frequently defoliated plants. High-P plants extracted more water per unit time, were able to maintain a higher Ψleaf in dry soil than low-P plants, displayed minimal water stress symptoms, and recovered completely on rewatering. High-P, frequently defoliated clover plants displayed minimal water stress symptoms in dry soil, whereas frequently defoliated low-P plants showed extreme symptoms; these plants were unable to recover from severe water stress and most plants died during the final drying cycle. Infrequently defoliated, low-P plants partially recovered from the water stress condition, but the recovery was slower than that for infrequently defoliated high-P plants. The findings suggest that the combination of dry soil, low P supply, and frequent defoliation that would result from heavy grazing would threaten the survival of white clover plants in the field.

Defoliation frequency and the response by white clover to increasing phosphorus supply 1. Leaf dry matter yield and plant morphology responses

1997 ◽  
Vol 48 (1) ◽  
pp. 111 ◽  
Author(s):  
D. K. Singh ◽  
P. W. G. Sale
Keyword(s):  
Leaf Area ◽  
White Clover ◽  
Dry Matter ◽  
Leaf Size ◽  
Plant Morphology ◽  
Application Rate ◽  
Leaf Number ◽  
Growth And Survival ◽  
Defoliation Frequency ◽  
P Supply

A glasshouse experiment was carried out to determine how an increasing P supply influences the growth and survival of white clover plants subjected to a range of defoliation frequencies. Treatments involved the factorial combination of P application rate (0, 30, 90, and 180 mg/pot) to a P-deficient Krasnozem soil and defoliation frequency (1, 2, or 4 defoliations over 36 days). The survival of P-deficient plants was threatened by the most frequent defoliation; their leaf area declined owing to a reduction in leaf number and individual leaf size with each successive defoliation. Increasing the P supply to 180 mg/pot reversed this downward trend as the high P plants were able to maintain leaf area by increasing leaf size and number. Increasing the frequency from 1 to 4 defoliations over the 36 days also changed the form of the leaf dry matter response to added P, from an asymptotic to a linear response. The P requirement of white clover for maximum leaf yield therefore increased under frequent defoliation. This effect was also apparent for a range of morphological measurements including stolon elongation rate, leaf area, root mass, leaf number, and stolon number, where the magnitude of the P response was consistently greater for frequently defoliated plants. Exceptions included stolon mass, which responded more to P addition under infrequent defoliation.

Defoliation frequency and the response by white clover to increasing phosphorus supply 2. Non-structural carbohydrate concentrations in plant parts

1997 ◽  
Vol 48 (1) ◽  
pp. 119 ◽  
Author(s):  
D. K. Singh ◽  
P. W. G. Sale
Keyword(s):  
White Clover ◽  
Soluble Sugars ◽  
Dry Weight ◽  
Starch Concentration ◽  
Plant Parts ◽  
Carbohydrate Concentration ◽  
Structural Carbohydrate ◽  
Defoliation Frequency ◽  
The Relationship ◽  
P Supply

The concentrations of total non-structural carbohydrate (%TNC) and its various forms (soluble sugars and starch) were measured in white clover plants that were grown in a glasshouse with different levels of P supply (0, 30, 90, and 180 mg/pot) and subjected to 3 defoliation frequencies (1, 2, and 4 defoliations over 36 days). Frequent defoliation reduced %TNC. Increasing P supply to the clover plants had the opposite effect, but to a lesser extent, and tended to reverse the decline in %TNC resulting from frequent defoliation. Stolons were the plant parts where most of the non-structural carbohydrate reserves were stored, with concentrations varying from <2 to >11% TNC on a dry weight basis, according to the treatment received. Minimal changes occurred in the %TNC for the leaves or roots as a result of treatments. The fluctuations in non-structural carbohydrate concentration in the stolons were mainly due to changes in the starch concentration, since the stolon sugar concentration was relatively constant between various treatments. A logistic curve closely defined the relationship (r2 = 0·98) between the starch concentration in the stolons and dry matter yield of leaves, suggesting that stolon starch reserves are a function of the size of the leaf canopy. Canopy size, in turn, was dependent on the duration of the regrowth period and, to a lesser extent, on the P supply. The maximum starch concentration in the stolons was around 8% under the conditions of this experiment.

Defoliation frequency and cultivar effects on the storage and utilisation of stolon and root reserves in white clover

2000 ◽  
Vol 51 (8) ◽  
pp. 1039 ◽  
Author(s):  
A. R. Lawson ◽  
K. B. Kelly ◽  
P. W. G. Sale
Keyword(s):  
White Clover ◽  
Plant Size ◽  
Water Soluble ◽  
Cultivar Differences ◽  
Soluble Carbohydrate ◽  
Leaf Production ◽  
Plant Weight ◽  
Stolon Length ◽  
Defoliation Frequency ◽  
Leaf Appearance

The effects of defoliation frequency (2 or 6 defoliations over a 91-day period) on the reserve status and growth rate of 2 white clover cultivars, cvv. Irrigation (medium-leafed) and Haifa (large-leafed), were examined over the final 42 days of the defoliation treatments. The clover plants consisted of single stolons growing in a sand/scoria mix in an unheated glasshouse, and were fertilised weekly with a solution containing essential nutrients excluding nitrogen. More frequent defoliation reduced the leaf appearance rate, stolon elongation rate, and plant size, and increased stolon death, with all of these effects being less pronounced in Irrigation than in Haifa (18% v. 30%, 60% v. 80%, and 23% v 34%, respectively, for leaf appearance rates, stolon elongation rates, and the proportion of stolon length that died). With infrequent defoliation, the combined utilisation of starch and water-soluble carbohydrate (WSC) reserves in the first 14 days after defoliation was equivalent to 15% of the plant weight at defoliation, and to 95% of the new leaf produced during that period. Frequent defoliation reduced the reserve content and remobilisation less in Irrigation than in Haifa, with the combined mass of remobilised starch and WSC over the first 14 days after defoliation being 2.9% and 2.0% of the plant weight at defoliation, and 29% and 19% of leaf production over that period, for Irrigation and Haifa, respectively. The greater reserve mobilisation in Irrigation than in Haifa plants under frequent defoliation probably contributed to their higher growth rates and reduced stolon death. These cultivar differences with frequent defoliation suggest that Irrigation is more suited to frequent defoliation than Haifa.

Water stress affects the productivity, growth components, competitiveness and water relations of phalaris and white clover growing in a mixed pasture

1992 ◽  
Vol 43 (3) ◽  
pp. 659 ◽  
Author(s):  
L Guobin ◽  
DR Kemp ◽  
GB Liu
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
White Clover ◽  
Leaf Growth ◽  
Leaf Water ◽  
Water Potentials ◽  
Relative Water ◽  
Dry Conditions ◽  
Leaf Appearance ◽  
Water Contents

The effect of water stress during summer and recovery after rain on herbage accumulation, leaf growth components, stomatal conductance and leaf water relations of white clover (Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) was studied in an established mixed pasture under dryland (dry) or irrigated (wet) conditions. Soil water deficits under dry conditions reached 150 mm and soil water potentials in the top 20 cm declined to nearly -2 MPa after 50 days of dry weather. Water stress severely restricted growth of both species but then after rain fell, white clover growth rates exceeded those of phalaris. Under irrigation, white clover produced twice the herbage mass of phalaris but under dry conditions herbage production was similar from both species. Leaf appearance rates per tiller or stolon were slightly higher for white clover than phalaris but were reduced by 20% under water stress in both species. Leaf or petiole extension rates were more sensitive to water stress than leaf appearance rates and declined by 75% in phalaris and 90% in white clover. The ratio of leaf or petiole extension rates on dry/wet treatments was similar for both species in relation to leaf relative water contents, but in relation to leaf water potentials phalaris maintained higher leaf growth rates. Phalaris maintained a higher leaf relative water content in relation to leaf water potentials than did white clover and also maintained higher leaf water potentials in relation to the soil water potential in the top 20 cm. Stomata1 conductances for both species declined by 80-90% with increasing water stress, and both species showed similar stomatal responses to bulk leaf water potentials and leaf relative water contents. It is suggested that the poorer performance of white clover under water stress may be due principally to a shallower root system than phalaris and not due to any underlying major physiological differences. The white clover cultivar used in this study came from the mediterranean region and showed some different responses to water stress than previously published evidence on white clover. This suggests genetic variation in responses to water stress may exist within white clover. To maintain white clover in a pasture under dry conditions it is suggested that grazing practices aim to retain a high proportion of growing points.

scholarly journals Effects of composted oil palm bunch wastes and chemical fertilizer on growth of oil palm seedling under water stress condition

Agro-Science ◽  
2015 ◽  
Vol 12 (1) ◽  
pp. 17
Author(s):  
S Ovie ◽  
GU Nnaji ◽  
PO Oviasogie ◽  
PE Osayande ◽  
P Irhemu
Keyword(s):  
Water Stress ◽  
Oil Palm ◽  
Stress Condition ◽  
Chemical Fertilizer ◽  
Water Stress Condition ◽  
Palm Bunch

scholarly journals Competition between drought-tolerant upland rice cultivars and weeds under water stress condition

2013 ◽  
Vol 31 (2) ◽  
pp. 291-302 ◽  
Author(s):  
F.B. Cerqueira ◽  
E.A.L. Erasmo ◽  
J.I.C. Silva ◽  
T.V. Nunes ◽  
G.P. Carvalho ◽  
...  
Keyword(s):  
Water Stress ◽  
Leaf Area ◽  
Stress Condition ◽  
Upland Rice ◽  
Total Concentration ◽  
Dry Weight ◽  
Rice Cultivars ◽  
Drought Tolerant ◽  
Water Stress Condition ◽  
Water Conditions

The objective of this study was to evaluate the competitiveness of two cultivars of upland rice drought-tolerant, cultured in coexistence with weed S. verticillata, under conditions of absence and presence of water stress. The experiment was conducted in a greenhouse at the Experimental Station of the Universidade Federal de Tocantins, Gurupi-TO Campus. The experimental design was completely randomized in a factorial 2 x 2 x 4 with four replications. The treatments consisted of two rice cultivars under two water conditions and four densities. At 57 days after emergence, were evaluated in rice cultivars and weed S. verticillata leaf area, dry weight of roots and shoots and total concentration and depth of roots. Was also evaluated in rice cultivars, plant height and number of tillers. Water stress caused a reduction in leaf area, the concentration of roots and vegetative components of dry matter (APDM, and MSR MST) of rice cultivars and Jatoba Catetão and weed S. verticillata. The competition established by the presence of the weed provided reduction of all vegetative components (MSPA, and MSR MST) of cultivars and Jatoba Catetão. It also decreased the number of tillers, the concentration of roots and leaf area. At the highest level of weed competition with rice cultivars, a greater decrease in vegetative components and leaf area of culture, regardless of water conditions.

scholarly journals Effects of soil water depletion on the water relations in tropical kudzu

1999 ◽  
Vol 34 (7) ◽  
pp. 1151-1157
Author(s):  
Adaucto Bellarmino de Pereira-Netto ◽  
Antonio Celso Novaes de Magalhães ◽  
Hilton Silveira Pinto
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Content ◽  
Soil Water ◽  
Cover Crop ◽  
Soil Water Depletion ◽  
Pueraria Phaseoloides ◽  
Water Depletion ◽  
Relative Water ◽  
Dry Soil

Tropical kudzu (Pueraria phaseoloides (Roxb.) Benth., Leguminosae: Faboideae) is native to the humid Southeastern Asia. Tropical kudzu has potential as a cover crop in regions subjected to dryness. The objective of this paper was to evaluate the effect of soil water depletion on leaflet relative water content (RWC), stomatal conductance (g) and temperature (T L) in tropical kudzu. RWC of waterstressed plants dropped from 96 to 78%, following a reduction in SWC from 0.25 to 0.17 g (H2O).g (dry soil)-1.Stomatal conductance of stressed plants decreased from 221 to 98 mmol.m-2.s-1, following the reduction in soil water content (SWC). The day after re-irrigation, g of water stressed plants was 15% lower than g of unstressed plants. Differences in T L between waterstressed and unstressed plants (deltaT L) rose linearly from 0.1 to 2.2ºC following progressive water deficit. RWC and T L of waterstressed plants paralled RWC and T L of unstressed plants the day after reirrigation. The strong decrease in SWC found in this study only induced moderate water stress in tropical kudzu. In addition, tropical kudzu recover rapidly from the induced water stress after the re-irrigation.

A viviparous mutant of maize exhibiting permanent water stress symptoms

2010 ◽  
Vol 64 (1) ◽  
pp. 99-108
Author(s):  
Anna Giulini ◽  
Nicoletta La Rocca ◽  
Diego Durantini ◽  
Antonino Malgioglio ◽  
Francesca Dalla Vecchia ◽  
...  
Keyword(s):  
Water Stress ◽  
Stress Symptoms
Sign in / Sign up

Export Citation Format

Share Document