Carbon and water economy of Australian NAD-ME and NADP-ME C4 grasses

2001 ◽  
Vol 28 (3) ◽  
pp. 213 ◽  
Author(s):  
Oula Ghannoum ◽  
Susanne von Caemmerer ◽  
Jann P. Conroy

C4 grasses are grouped into three biochemical subtypes,NAD malic enzyme (NAD–ME), NADP malic enzyme (NADP–ME)and phosphoenolpyruvate carboxykinase (PCK), possessingcharacteristic leaf anatomy, biochemistry and physiology. This studyinvestigates the physiological implications of these differences by comparing growth, water use efficiency (WUE, dry matter gain per unit water transpired) and gas exchange characteristics of NAD–MEand NADP–ME C4 grasses belonging to threetaxonomic groups (main Chloroid assemblage, Paniceae and Andropogoneae). Wegrew 28 C4 grasses from seeds for 6 weeks in aglasshouse under ample water and nutrients in winter and summer. Theinter-specific variation in plant dry mass (30-fold) was much greater thanthat in WUE (2-fold). There was no significantdifference in average WUE between NAD–ME andNADP–ME grasses. Average plant dry mass andWUE were highest in the Paniceae (mostlyNADP–ME), lowest in the Andropogoneae (NADP–ME) and intermediate in the Chloroid (NAD–ME). CO2assimilation rate (A), stomatal conductance(g) and the ratio of intercellular to ambient CO2 partial pressure (pi/p a )were measured under standard conditions at high light. AverageA and g were slightly higher inNADP–ME than NAD–ME grasses, but pi/p awas similar for the two subtypes. A did not differbetween winter and summer experiments in spite of a 3-fold difference inmaximal daily irradiance. Dry matter accumulation correlated positively withleaf area ratio (LAR; plant leaf area per unit plant drymass) and specific leaf area (SLA; leaf area per unitleaf dry mass) in NAD–ME, but not NADP–ME, grasses.Variation in A (expressed on a per area basis) did notcorrelate with biomass accumulation or SLA. Whenexpressed on a dry mass basis, A correlated withSLA in all C4 grasses. This studyshows that there is large inter-specific variation in growth among the C4 grasses, but average WUE andA/g are similar forNAD–ME and NADP–ME species under well-wateredconditions.

2002 ◽  
Vol 29 (11) ◽  
pp. 1337 ◽  
Author(s):  
Oula Ghannoum ◽  
Susanne von Caemmerer ◽  
Jann P. Conroy

We investigated the response to drought of nine NAD–malic enzyme (NAD–ME) and nine NADP–malic enzyme (NADP–ME) C4 grasses. Species were grown from seeds in potted soil in a glasshouse. Seedlings were either watered regularly or exposed to two successive drying cycles of 8–10 d each, after which plants were harvested. Under well-watered conditions, average water use efficiency (WUE; dry mass gain per unit water transpired) was similar for NAD–ME and NADP–ME C4 grasses, and ranged between 6.0 and 8.7 g dry mass kg–1 H2O. Drought enhanced WUE of most species, but to a significantly greater extent in NAD–ME (1.20-fold) than NADP–ME (1.11-fold) grasses. Inhibition of dry matter accumulation (average of 12%) and shoot elongation under drought was similar among the C4 grasses. Leaf dry matter carbon (δ13C) and oxygen (δ18O) isotope compositions were significantly different between the two C4 subtypes. Leaf δ13C averaged –13.3 and –12.2, and leaf δ18O averaged 26.0 and 26.9 in well-watered NAD–ME and NADP–ME grasses, respectively. Drought significantly reduced leaf δ13C in most C4 grasses by an average 0.5. Leaf δ18O was not significantly affected by drought, indicating that leaf δ18O does not reflect drought-induced changes in leaf transpiration of C4 grasses. In the experiment reported here, NAD–ME grasses increased their WUE under drought to a greater extent than their NADP–ME counterparts. Increased WUE of the C4 grasses under drought was primarily related to control of water loss relative to carbon gain at the leaf, rather than the plant, level.


1998 ◽  
Vol 123 (6) ◽  
pp. 973-979 ◽  
Author(s):  
Keith A. Funnell ◽  
Errol W. Hewett ◽  
Ian J. Warrington ◽  
Julie A. Plummer

Dry matter accumulation and partitioning in plants of Zantedeschia Spreng. `Best Gold' aff. Z. pentlandii (Wats.) Wittm. (syn. Richardia pentlandii Wats.) were quantified under a range of temperature and photosynthetic photon flux (PPF) regimes using plant growth analysis. The relative rate of dry matter accumulation [relative growth rate (RGRM), g·g-1·d-1] was highly correlated with the partitioning of the daily increment of dry matter into leaf tissue [leaf matter partitioning (LMP), g·d-1 per g·d-1]. In contrast, a poor correlation existed between RGRM and net assimilation rate (NAR, g·m-2·d-1). Maximum values of RGRM increased linearly with increasing temperature (from 13 to 28 °C), with a base temperature of 2.1 ± 2.7 °C. The optimum temperature for growth was PPF dependent with maximum total plant dry mass occurring under high PPF (694 μmol·m-2·s-1) at 25 °C. However, as the plant responded to PPF by altering LMP, final total plant dry mass was actually greater under the low PPF regime (348 μmol·m-2·s-1) at temperatures <22 °C. The optimum temperature for dry matter accumulation was close to the average daily air temperature during the growing season for the natural habitat of the parent species. Similarly, the greater dry matter accumulation under the combination of either low PPF and cooler temperatures or high PPF and warmer temperatures was paralleled by the diversity of PPF habitats in the natural open grassland and forest margin the parent species occupies. It is therefore suggested that Zantedeschia `Best Gold' is well adapted to optimize growth under these environmental conditions.


1998 ◽  
Vol 123 (1) ◽  
pp. 52-55 ◽  
Author(s):  
Takashi Nishizawa ◽  
Yoshihiro Shishido

June-bearing strawberry plants (Fragaria ×ananassa Duch. `Morioka 16') were forced in a greenhouse and either allowed to fruit or deflowered continuously. Plants were harvested at the start of the experiment (day 0), at full bloom (day 35), during rapid growth of green fruit (day 53), at first fruit coloring (day 63), at full coloring of the primary and some secondary fruit in the primary and secondary inflorescences (day 68), and at overripe of many primary and secondary fruit in the primary and secondary inflorescences (day 81). Dry matter accumulation in the vegetative organs in fruiting plants was less than that in deflowered plants as the fruit matured, but the total plant dry mass did not differ significantly between treatments throughout the forcing period. Reducing sugar and sucrose concentrations in roots, crown, and old leaves decreased continuously until day 68, particularly in roots. The concentrations did not differ between treatments. Starch concentrations in roots declined rapidly in both treatments between day 0 and day 35, and then the decline slowed. Starch level was significantly lower in the roots of fruiting plants from day 35 through fruit harvest. These results suggest that carbohydrate reserves in roots of forced June-bearing strawberry plants are used primarily to support the growth of inflorescences and developing leaves. They are less available for fruit growth and maturation since the levels are already relatively low by this stage.


Author(s):  
Muhammad Zeeshan Mehmood ◽  
Ghulam Qadir ◽  
Obaid Afzal ◽  
Atta Mohi Ud Din ◽  
Muhammad Ali Raza ◽  
...  

AbstractSeveral biotic and abiotic stresses significantly decrease the biomass accumulation and seed yield of sesame crops under rainfed areas. However, plant growth regulators (such as Paclobutrazol) can improve the total dry matter and seed production of the sesame crop. The effects of the paclobutrazol application on dry matter accumulation and seed yield had not been studied before in sesame under rainfed conditions. Therefore, a two-year field study during 2018 and 2019 was conducted with key objectives to assess the impacts of paclobutrazol on leaf greenness, leaf area, total dry matter production and partitioning, seed shattering, and seed yield of sesame. Two sesame cultivars (TS-5 and TS-3) were treated with four paclobutrazol concentrations (P0 = Control, P1 = 100 mg L−1, P2 = 200 mg L−1, P3 = 300 mg L−1). The experiment was executed in RCBD-factorial design with three replications. Compared with P0, treatment P3 improved the leaf greenness of sesame by 17%, 38%, and 60% at 45, 85, and 125 days after sowing, respectively. However, P3 treatment decreased the leaf area of sesame by 14% and 20% at 45 and 85 days after sowing than P0, respectively. Compared with P0, treatment P3 increased the leaf area by 46% at 125 days after sowing. On average, treatment P3 also improved the total biomass production by 21% and partitioning in roots, stems, leaves, capsules, and seeds by 23%, 19%, 23%, 22%, and 40%, respectively, in the whole growing seasons as compared to P0. Moreover, under P3 treatment, sesame attained the highest seed yield and lowest seed shattering by 27% and 30%, respectively, compared to P0. This study indicated that by applying the paclobutrazol concentration at the rate of 300 mg L−1 in sesame, the leaf greenness, leaf areas, biomass accumulation, partitioning, seed yield, and shatter resistance could be improved. Thus, the optimum paclobutrazol level could enhance the dry matter accumulation and seed production capacity of sesame by decreasing shattering losses under rainfed conditions.


2010 ◽  
Vol 39 (8) ◽  
pp. 1666-1675 ◽  
Author(s):  
Marcio Mahmoud Megda ◽  
Francisco Antonio Monteiro

The objective of this work was to study morphogenic characteristics, and dry matter production of roots and shoots of marandu palisadegrass (Brachiaria brizantha cv. Marandu) submitted to combinations of nitrogen and potassium, in a nutritive solution, employing silica as substrate. The experiment was carried out in a greenhouse during the summer. It was used a 5² fractionated factorial scheme with 13 combinations of nitrogen and potassium, which were distributed in a randomized block design, with four replications. The nitrogen × potassium interaction was significant for the number of tillers and leaves, for leaf area, for shoots and root section dry mass, for total length and surface and specific length and surface in the roots. Production of aerial part dry mass positively correlated with the number of tillers and leaves and grass leaf area. Nitrogen rates modulated the root system development, and the root specific length and surface decreased when high rates of nitrogen and potassium were supllied. Nitrogen and potassium influence Marandu palisadegrass morphogenic characteristics, which are determinant for grass dry matter production.


2004 ◽  
Vol 61 (5) ◽  
pp. 496-500 ◽  
Author(s):  
Anacleto Ranulfo dos Santos ◽  
Waldssimiler Teixeira de Mattos ◽  
Ana Aparecida da Silva Almeida ◽  
Francisco Antonio Monteiro ◽  
Beatriz Dias Corrêa ◽  
...  

Alfalfa cultivar Crioula (Medicago sativa cv. Crioula) is grown in South Brazil and only a few studies on the plants' boron requirement are available. A greenhouse experiment was carried out with alfalfa to measure boron acquisition, production and distribution in the plant; data on critical level and production potentials were recorded. Plants were grown in ground quartz added with 1 L of solution, with the following boron rates: 0, 0.0625, 0.125, 0.25, 0.50, 1.00, and 2.00 mg L-1. Plants were harvested at 46 days of growth. Forage dry mass was increased by boron supply and dry matter accumulation was considerably low in control. Boron concentration in the leaves was higher than in the stems or roots. Boron utilization from the external solution reached 90% at 0.0625 mg L-1 and sharply decreased with further increasing boron rates. Boron concentration and content in the leaves and in plant tops were at maximum when applied boron was between 1.5 and 1.6 mg L-1. Critical levels of boron in plant were 61 mg kg-1 in the leaves and 39 mg kg-1 in plant tops for this cultivar of alfalfa.


1999 ◽  
Vol 34 (6) ◽  
pp. 944-952 ◽  
Author(s):  
Moacyr Bernardino Dias-Filho

Ipomoea asarifolia (Desr.) Roem. & Schultz (Convolvulaceae) and Stachytarpheta cayennensis (Rich) Vahl. (Verbenaceae), two weeds found in pastures and crop areas in Brazilian Amazonia, were grown in controlled environment cabinets under high (800-1000 µmol m-² s-¹) and low (200-350 µmol m-² s-¹) light regimes during a 40-day period. For both species leaf dry mass and leaf area per total plant dry mass, and leaf area per leaf dry mass were higher for low-light plants, whereas root mass per total plant dry mass was higher for high-light plants. High-light S. cayennensis allocated significantly more biomass to reproductive tissue than low-light plants, suggesting a probably lower ability of this species to maintain itself under shaded conditions. Relative growth rate (RGR) in I. asarifolia was initially higher for high-light grown plants and after 20 days started decreasing, becoming similar to low-light plants at the last two harvests (at 30 and 40 days). In S. cayennensis, RGR was also higher for high-light plants; however, this trend was not significant at the first and last harvest dates (10 and 40 days). These results are discussed in relation to their ecological and weed management implications.


2011 ◽  
Vol 59 (1) ◽  
pp. 35-45
Author(s):  
E. Sugár ◽  
Z. Berzsenyi

The effect of nitrogen (N) fertilisation on the growth of winter wheat varieties was examined in three diverse years using the functional method of growth analysis. The main plot in the two-factorial, split-plot experiment was the N treatment and the subplot the variety. The wheat varieties Mv Toborzó (extra-early), Mv Palotás (early) and Mv Verbunkos (mid-early) were treated with N rates of 0, 80, 160 and 240 kg N ha−1 (N0, N80, N160, N240). The Hunt-Parsons (HP) program fitted a third-degree exponential function to the dry matter and leaf area data. In 2007 and 2008 dry matter accumulation continued up to the N240 rate and in 2009 to the N160 rate. In all three years the highest value was recorded for Mv Verbunkos (4.62 g plant−1 in 2007, 4.63 g in 2008 and 4.51 g in 2009). The highest value of maximum leaf area (237.5 cm2) was found for Mv Verbunkos in the N240 treatment. The maximum values of leaf area in each N treatment, averaged over years and varieties (cm2 plant−1), were as follows: N0: 86.2; N80: 141.0; N160: 164.0; N240: 173.1. The parameter AGRmean exhibited the highest value (8.04 g day−1 102) in the N160 treatment, while among the varieties Mv Verbunkos had the highest mean value (7.18 g day−1 102). The highest value of RGRmean was achieved by Mv Toborzó in the N160 treatment in 2009 (3.94 g g−1 day−1 102). The value of NARmean increased up to fertiliser rates of N160 and N240, with mean values (g m−1 day−1) of N0: 2.35, N80: 2.44, N160: 2.53 and N240: 2.47. The highest value of NAR (3.29 g m−1 day−1) was obtained for Mv Palotás in the N160 treatment in 2008. On average the greatest value of LARmax was recorded in the N160 treatment (172.8 cm2 g−1), while the highest absolute value (213.6 cm2 g−1) was achieved by Mv Toborzó in 2008. The unfavourable effect of the drought in 2007 was clearly reflected in the values of the growth parameters.


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