Search Results

You are looking at 31 - 40 of 521 items for :

  • "water uptake" x
  • Refine by Access: All x
Clear All
Free access

D.M. Glenn and W.V. Welker

We determined how differences in peach tree water use and shoot and root growth due to ground cover treatments are affected by tree response and soil conditions in the adjacent soil environment. Ground cover combinations of bare soil (BS), a killed K-31 tall fescue sod (KS), a living Poa trivialis sod (PT), and a living K-31 tall fescue sod (LS) were imposed on 50% of the soil surface in greenhouse studies. The ground cover on 50% of the soil surface influenced root and top growth of the peach trees [Prunus persica (L) Batsch], water use, and NO3-N levels in the opposing 50%, depending on the competitiveness of the cover crop (LS vs. PT and KS) and characteristics of the soil (BS vs. KS). Tree growth was allometrically related to root growth.

Open access

H. C. De Roo

Abstract

The water economy of plants often is seriously unbalanced by root destruction or vascular occlusion induced by various rot organisms. Water absorption by the roots and water transport within the plants is impeded and wilting follows. Beckman (1) reviewed the literature on the histological and physiological changes in host plants infected with pathological wilts. Dimond and Edgington (2), studying the mechanics of water transport in healthy and Fusarium-vrilted tomato plants, pointed out the tremendous pressure deficits that are required to maintain normal water flow into leaves through partially plugged vessels.

Open access

C. S. Tan and J. M. Fulton

Abstract

Root systems were studied to determine if differences in utilization of soil moisture were associated with the extent and number of roots produced by corn and tomato. Growth room studies for both crops indicated that the reduction in transpiration when the upper portion of the root zone was dry was greater than when the lower portion was dry. Total root length of corn was about twice that of tomato roots. However, no direct relationship between the total amount of root length and transpiration was found. Roots of corn and tomato in the field extended beyond the maximum depth measured (100 cm) between 42 – 46 days after establishment. The spatial density of corn roots was much greater than that of tomato roots, especially as depths increased. This difference possibly explains the use of stored soil moisture by corn. On the other hand, the capacity of tomatoes to extract large amounts of water from the soil cannot be explained by the density and rooting depth. Perhaps this capacity is due to total root surface area differences or high absorption capacity of tomato root system.

Free access

Mark Rieger

Growth, gas exchange, root hydraulic conductivity, and drought response of seedling and rooted cuttings of Lovell and Nemaguard peach [Prunus persica (L.) Batsch], and Carrizo (Poncirus trifoliata × Citrus sinensis) and sour orange (C. aurantium L.) citrus rootstocks were compared to determine the influence of propagation method on these characteristics. Rooted peach cuttings had a higher proportion of root biomass in fibrous roots (≤ mm in diameter) and lower root: shoot ratios than seedlings, although this did not occur in citrus. Net CO2 assimilation (A) was higher for peach seedlings than for cuttings, but similar for `Redhaven' (RH) scions on either seedling- or cutting-propagated rootstocks, suggesting that leaf-associated factors were responsible for differences. As in peach, A was higher for Carrizo seedlings than for cuttings, but A was not affected by propagation method in sour orange. Peach seedlings maintained higher A than cuttings as water potentials declined during short-term soil drying, although in citrus this occurred only for Carrizo. RH scions on either root type exhibited similar declines in A as soil dried, indicating the lack of a rootstock effect. Root hydraulic conductivity (Lp) was similar between seedlings and cuttings of all cultivars when expressed on a length basis. Leaf conductance and osmotic adjustment were similar for RH scions on seedling- or cutting-propogated rootstocks during 45 days of drought stress, indicating the lack of a rootstock effect on long-term stress response.

Free access

Moritz Knoche, Eckhard Grimm, and Henrik Jürgen Schlegel

osmotic water uptake through the wetted fruit skin or the pedicel during and after precipitation or heavy dew ( Considine and Kriedemann, 1972 ; Measham et al., 2009 ; Sekse, 1995 ; Sekse et al., 2005 ). As a consequence of water uptake, fruit volume

Free access

Motoaki Doi and Michael S. Reid

Regardless of their maturity at harvest, the vase life of cut inflorescences of the hybrid Limonium `Fantasia' placed in deionized water was 4 to 5 days. A vase solution containing Physan (a quaternary ammonium disinfectant solution) at 200 μl·liter–1 and 20 g sucrose/liter not only prolonged the longevity of individual florets but also promoted bud opening so that the vase life of cut inflorescences extended to 17 days. Pulse treatment with 100 g sucrose/liter in combination with Physan at 200 μl·liter–1 for 12 hours partially substituted for a continuous supply of sucrose. Including 30 mg gibberellic acid/liter in the vase solution was without benefit.

Free access

S.M. Smith, J.W. Scott, J.A. Bartz, and S.A. Sargent

temperatures and dryer stem scars. Keeping fruit shaded after harvest is helpful because it reduces sun-induced fruit warming, which reduces the demand for water heating and cooler fruit are less prone to water uptake than warm fruit ( Bartz, 1999 ). Soft rot

Full access

Erin P. Moody, John M. Dole, and Jared Barnes

accelerated by increased stomatal opening, transpiration will exceed uptake and water deficiency will occur. Thus, solutes are frequently added to vase solutions such as 8-hydroxyquinoline citrate (8-HQC), which can increase water uptake ( van Doorn, 1997

Free access

Miguel Urrestarazu, Isidro Morales, Tommaso La Malfa, Ruben Checa, Anderson F. Wamser, and Juan E. Álvaro

The management of water and nutrient ions, such as nitrate, has been studied extensively in recent decades. Increasingly efficient models have been developed for the use of water and nutrients through the automation of fertigation techniques. The application of a fertigation volume for a duration four times longer than applied on the control was evaluated. In Almería (Spain), one pepper crop and two tomato crops—with and without grafting—were grown between Oct. 2013 and June 2014 in a soilless system with a coir substrate. The effects on root growth, plant growth, production, and quality were measured. The following parameters for the fertigation of the nutrient solution and drainage were recorded: % drainage volume, electrical conductivity (EC) of the nutrient solution, pH, and concentration of nitrates and potassium. The absorption of potassium and nitrate, and the nitrate emissions of the drainage were estimated. The results showed an increase in the root volume and an improved distribution in the cultivation unit for the treatment application in the pepper crop. Slowing the applied fertigation improved the absorption of water and nitrates, and the production in the ungrafted tomato and pepper crops, while the grafted tomato crop was unaffected. Nitrate emissions were lower in the evaluated treatment of the pepper and ungrafted tomato crops. The fruit quality parameters were unaffected.

Open access

Dariusz Swietlik

Abstract

Studies were conducted to compare responses of pressure- and transpiration-induced water fluxes (Jv) through root systems of sour orange (Citrus aurantium L.) (SO) seedlings and to quantify the apoplastic component of fluxes in the both systems. Roots excised from water-cultured SO seedlings were sealed in a nutrient solution-filled pressure chamber and pressurized at 0.5 MPa with air, N2, or CO2. Changing the pressurizing gas from air to N2 or CO2 reduced Jv, but the response to CO2 was more pronounced than to N2. The fluxes recovered when N2 and CO2 were in turn replaced by air. Transpiration of water-culture-grown intact SO seedlings responded similarly to changes in gasses bubbled through the nutrient solution. The Jv in excised root systems was decreased at elevated salt concentration in the root medium, a phenomenon commonly observed in intact plants. Root conductance taken from the slopes of the linear portion of pressure/flux curves was lower at low than high salt levels. The apoplastic water fluxes through pressurized roots and intact SO seedlings was quantified using trisodium 3-hydroxy-5,8,10-pyrenetrisulfonate. The increased proportion of the apoplastic component in pressure-, compared to transpiration-induced, fluxes indicates that root pressurization opens one or more new avenues for water transport that are not operative in a transpiring seedling. Steady-state flow rates through the roots pressurized at 0.5 MPa were attained within ≈3 hr.