Genetic variability in sunflower cultivars under drought. II. Growth and water relations

1986 ◽  
Vol 37 (6) ◽  
pp. 583 ◽  
Author(s):  
C Gimenez ◽  
E Fereres
Keyword(s):  
Leaf Area ◽  
Carbon Balance ◽  
Genotypic Variation ◽  
Biomass Accumulation ◽  
Reproductive Period ◽  
Water Extraction ◽  
Genotypic Differences ◽  
Leaf Area Duration ◽  
Root Water Extraction ◽  
Yield Responses

Experiments were conducted between 1981 and 1983 at Cordoba, Spain, to determine the morphophysiological basis for the differences in yield responses to drought of eight sunflower genotypes. There was genotypic variation in most characters examined, particularly in maximum leaf area and in leaf area duration, biomass accumulation and distribution, and in root water extraction. Long-season genotypes had greater leaf area and produced more biomass under drought conditions, exploring the subsoil down to 270 cm. Short-season genotypes restricted water extraction to the top 180 cm of the soil profile and had about half of the leaf area duration of a long-season cultivar. Evidence is presented of small differences in osmotic adjustment among genotypes. The relations between leaf area and grain yield as well as calculations of a carbon balance for the reproductive period suggest genotypic differences in photosynthetic efficiency under drought.

scholarly journals Measurement and Modeling of Carbon Balance of Apple Trees

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 551B-551
Author(s):  
Alan N. Lakso
Keyword(s):  
Leaf Area ◽  
Carbon Balance ◽  
Dry Matter ◽  
Early Spring ◽  
Carbon Production ◽  
Large Size ◽  
Optimal Balance ◽  
Leaf Area Duration ◽  
High Record ◽  
Very High

Apples have very high record yields (about 140 tons/ha sustained) that demand large amounts of carbon to be produced and partitioned into both fruit and vegetative structures. Even though large quantities of dry matter can be produced, profitability depends on the management of the carbon production and partitioning to produce the optimal balance of yield and fruit quality. The productivity is mostly related to moderate photosynthesis rates per leaf area, long leaf area duration, high seasonal radiation interception, relatively low respiration, and very high harvest index. Due to the perennial nature and large size, few good estimates of seasonal carbon balance are available. Models have been developed, but are not wellvalidated yet, but general seasonal trends are apparent. Daily net CO2 exchange begins negative with early spring growth, reaches zero near bloom, peaks about 6 to 10 weeks after bloom, then gradually declines until leaf fall. The demand of the fruit appears to increase exponentially during cell division, then levels off to a relatively constant demand until harvest. Experiments and modeling suggests that if fruit development is limited by carbon availability, the probability increases in heavily cropping trees, and will occur at about 2 to 4 weeks after bloom and before harvest. Best carbon balance appears to occur in relatively cool temperatures and in very long seasons.

Growth, ion content, gas exchange, and water relations of wheat genotypes differing in salt tolerances

2005 ◽  
Vol 56 (2) ◽  
pp. 123 ◽  
Author(s):  
Salah E. El-Hendawy ◽  
Yuncai Hu ◽  
Urs Schmidhalter
Keyword(s):  
Salt Tolerance ◽  
Leaf Area ◽  
Water Relations ◽  
Genotypic Variation ◽  
Turgor Pressure ◽  
Mineral Nutrient ◽  
Genotypic Differences ◽  
Wheat Genotypes ◽  
Spad Value ◽  
Osmotic Potentials

Although the mechanisms of salt tolerance in plants have received much attention for many years, genotypic differences influencing salt tolerance still remain uncertain. To investigate the key physiological factors associated with genotypic differences in salt tolerance of wheat and their relationship to salt stress, 13 wheat genotypes from Egypt, Australia, India, and Germany, that differ in their salt tolerances, were grown in a greenhouse in soils of 4 different salinity levels (control, 50, 100, and 150 mm NaCl). Relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), photosynthesis, chlorophyll content (SPAD value), and leaf water relations were measured at Days 45 and 60 after sowing. Mineral nutrient content in leaves and stems was determined at Day 45 and final harvest. Salinity reduced RGR, NAR, photosynthetic rate, stomatal conductance, water and osmotic potentials, and K+ and Ca2+ content in stems and leaves at all times, whereas it increased leaf respiration, and Na+ and Cl– content in leaves and stems. LAR was not affected by salinity and the effect of salinity on SPAD value was genotype-dependent. Growth of salt-tolerant genotypes (Sakha 8, Sakha 93, and Kharchia) was affected by salinity primarily due to a decline in photosynthetic capacity rather than a reduction in leaf area, whereas NAR was the more important factor in determining RGR of moderately tolerant and salt-sensitive genotypes. We conclude that Na+ and Cl– exclusion did not always reflect the salt tolerance, whereas K+ in the leaves and Ca2+ in the leaves and stems were closely associated with genotypic differences in salt tolerance among the 13 genotypes even at Day 45. Calcium content showed a greater difference in salt tolerance among the genotypes than did K+ content. The genotypic variation in salt tolerance was also observed for the parameters involved in photosynthesis, and water and osmotic potentials, but not for turgor pressure.

Drought resistance and soil water extraction of a perennial C4 grass: contributions of root and rhizome traits

2014 ◽  
Vol 41 (5) ◽  
pp. 505 ◽  
Author(s):  
Yi Zhou ◽  
Christopher J. Lambrides ◽  
Shu Fukai
Keyword(s):  
Soil Water ◽  
Drought Resistance ◽  
Root Length Density ◽  
Genotypic Variation ◽  
Canopy Temperature ◽  
Root Diameter ◽  
Water Extraction ◽  
Soil Drought ◽  
Genotypic Differences ◽  
Soil Water Extraction

Previously, we showed that genotypic differences in soil water extraction were associated with drought response, but we did not study underground root and rhizome characteristics. In this study, we demonstrate a similar relationship between drought resistance and soil water extraction but investigate the role of underground organs. Eighteen bermudagrass genotypes (Cynodon spp.) from four climatic zones were assessed under continuous drought at two locations with contrasting soils and climates. The criterion for drought resistance was the duration required to reach 50% green cover (GC50) after water was withheld. GC50, physiological traits, rhizome dry matter (RhDM), root length density (RLD) and average root diameter (ARD) were determined in both locations; water extraction was measured in one location. Large genotypic variation for drought resistance was observed in both locations, with GC50 being 187–277 days in a clay soil and 15–27 days in a sandy soil. Drought-resistant genotypes had greater soil water extraction and a higher water uptake rate. GC50 was correlated with relative water content (r = 0.76), canopy temperature differential (r = –0.94) and photosynthetic rate (r = 0.87) measured during drought; RhDM (r = 0.78 to ~0.93) before and after drought; and ARD after drought (r = 0.82 to ~0.94); GC50 was not correlated with RLD. Ecotypes collected from the Australian Mediterranean zone had superior drought resistance and were characterised by a large rhizome network. This is the first comprehensive study with perennial C4 grasses describing the association between water extraction, root distribution, rhizomes and drought resistance.

Can early vigour occur in combination with drought tolerance and efficient water use in rice genotypes?

2013 ◽  
Vol 40 (6) ◽  
pp. 582 ◽  
Author(s):  
Maria Camila Rebolledo ◽  
Delphine Luquet ◽  
Brigitte Courtois ◽  
Amelia Henry ◽  
Jean-Christophe Soulié ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Leaf Area ◽  
Water Use ◽  
Crop Improvement ◽  
Leaf Size ◽  
Biomass Accumulation ◽  
Tiller Number ◽  
Genotypic Differences ◽  
Early Vigour ◽  
Rice Genotypes

Selection for early vigour can improve rice (Oryza sativa L.) seedlings’ access to resources, weed competitiveness and yield. Little is known about the relationships between early vigour and drought tolerance. This study explored a panel of 176 rice genotypes in a controlled environment regarding a diversity of traits and trait combinations related to early vigour and water use under drought. The design excluded genotypic differences for root depth. We hypothesised that early vigour (as determined by biomass accumulation under well-watered conditions) was not independent from drought tolerance (determined by biomass accumulation maintenance under drought). Leaf size, developmental rate (DR) and tiller number contributed positively to shoot DW and leaf area, and thus vigour. Early vigour was negatively correlated with growth maintenance and water use efficiency under drought, suggesting tradeoffs. Three clusters of genotypes were identified based on the constitutive traits DR, specific leaf area, tiller number and leaf size. The less drought-tolerant cluster, mainly with lowland O. sativa indica rices, showed a sensitive transpiration response to the fraction of transpirable soil water; however, under well-watered conditions these genotypes were vigorous, with small leaves, high DR and high tillering. This experiment showed that the tradeoff between early vigour and drought tolerance was physiological and not a matter of access to water. The results are discussed with a view to identify drought adaptation strategies for crop improvement. Further improvement of multitrait phenotyping approaches is proposed.

Inheritance of coleoptile tiller appearance and size in wheat

2008 ◽  
Vol 59 (9) ◽  
pp. 863 ◽  
Author(s):  
G. J. Rebetzke ◽  
C. López-Castañeda ◽  
T. L. Botwright Acuña ◽  
A. G. Condon ◽  
R. A. Richards
Keyword(s):  
Leaf Area ◽  
Genetic Control ◽  
Genotypic Variation ◽  
Growth Stages ◽  
Genotypic Differences ◽  
Progeny Testing ◽  
Plant Leaf ◽  
Generation Means ◽  
Selection For ◽  
Seedling Leaf

Selection for rapid leaf area growth has the potential to increase wheat biomass, and both water-use efficiency and weed competitiveness early in the season. Several morphological components contribute to increased seedling leaf area, including rapid seedling emergence and production of longer, wider leaves. Early emergence of a large coleoptile tiller has also been demonstrated to increase plant leaf area and biomass in wheat and other grass seedlings. Yet little is known of the extent and nature of genotypic variation for coleoptile tiller growth in wheat. A random set of 35 wheat, barley, and triticale genotypes was evaluated in glasshouse and outdoor studies for seedling characteristics, including coleoptile tiller growth and total plant leaf area. Coleoptile tillers were produced more reliably for seedlings grown outdoors and when supplied with additional soil nitrogen. Genotypic differences in coleoptile tiller frequency and leaf area were large, ranging from 0 to 78% and from 0.0 to 1.4 cm2, respectively at very early growth stages. Australian commercial wheats tended to produce fewer coleoptile tillers of smaller size than overseas germplasm where the coleoptile tiller accounted for up to 12% of total seedling leaf area. This compared favourably with mainstem tiller leaf area, which ranged from 0 to 3.5 cm2 and accounted for up to 16% of plant leaf area. Broad-sense heritabilities were high for coleoptile tiller presence and size in favourable conditions (c. 75%) but low (c. 40%) for seedlings evaluated across nitrogen content-varying soils. Generation means analysis was used to investigate genetic control for coleoptile tiller growth across multiple populations. Significant (P < 0.05) differences were observed among generations for coleoptile tiller frequency and growth (numbers of leaves, leaf area, and biomass). These differences reflected strong additive genetic control with little evidence for any gene action × year interaction. Increases in coleoptile tiller frequency and mass were correlated with larger embryo size and wider seedling leaves to increase seedling leaf area (rg = 0.89). Comparisons between reciprocal F1 and F2 generation means indicated strong maternal effects for coleoptile tiller growth in some but not all crosses. Screening in favourable environments will increase heritability and aid in selection for progenies producing large coleoptile tillers. Evidence for additive genetic control should permit early generation selection but not without some progeny-testing for coleoptile tiller growth together with other early vigour components associated with increased plant leaf area.

scholarly journals Paclobutrazol Improves Sesame Yield by Increasing Dry Matter Accumulation and Reducing Seed Shattering Under Rainfed Conditions

2021 ◽  
Author(s):  
Muhammad Zeeshan Mehmood ◽  
Ghulam Qadir ◽  
Obaid Afzal ◽  
Atta Mohi Ud Din ◽  
Muhammad Ali Raza ◽  
...  
Keyword(s):  
Leaf Area ◽  
Seed Production ◽  
Seed Yield ◽  
Dry Matter ◽  
Biomass Accumulation ◽  
Total Biomass ◽  
Dry Matter Accumulation ◽  
Seed Shattering ◽  
Rainfed Conditions ◽  
Leaf Greenness

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.

Genotypic Variation in C and N Isotope Discrimination Suggests Local Adaptation of Heart-Leaved Willow

2021 ◽  
Author(s):  
Yi Hu ◽  
Robert D Guy ◽  
Raju Y Soolanayakanahally
Keyword(s):  
Isotopic Composition ◽  
Local Adaptation ◽  
N Uptake ◽  
Genotypic Variation ◽  
Carbon Isotopic Composition ◽  
Genotypic Differences ◽  
Clinal Variation ◽  
Trade Off ◽  
Uptake Efficiency ◽  
N Uptake Efficiency

Abstract Plants acquire multiple resources from the environment and may need to adjust and/or balance their respective resource-use efficiencies to maximize grow and survival, in a locally adaptive manner. In this study, tissue and whole-plant carbon isotopic composition (δ13C) and C/N ratios provided long-term measures of use efficiencies for water (WUE) and nitrogen (NUE), and a nitrogen isotopic composition (δ15N) based mass balance model was used to estimate traits related to N uptake and assimilation in heart-leaved willow (Salix eriocephala Michx.). In an initial common garden experiment consisting of 34 populations, we found population level variation in δ13C, C/N and δ15N, indicating different patterns in WUE, NUE and N uptake and assimilation. Although there was no relationship between foliar δ13C and C/N ratios among populations, there was a significant negative correlation between these measures across all individuals, implying a genetic and/or plastic trade-off between WUE and NUE not associated with local adaptation. To eliminate any environmental effect, we grew a subset of 21 genotypes hydroponically with nitrate as the sole N-source, and detected significant variation in δ13C, δ15N and C/N ratios. Variation in δ15N was mainly due to genotypic differences in the nitrate efflux/influx ratio (E/I) at the root. Both experiments suggested clinal variation in δ15N (and thus N uptake efficiency) with latitude of origin, which may relate to water availability and could contribute to global patterns in ecosystem δ15N. There was a tendency for genotypes with higher WUE to come from more water replete sites with shorter and cooler growing seasons. We found that δ13C, C/N, and E/I were not inter-correlated, suggesting that selection of growth, WUE, NUE and N uptake efficiency can occur without trade-off.

The net carbon balance in relation to growth and biomass accumulation of grapevines (Vitis vinifera cv. Semillon) grown in a controlled environment

2009 ◽  
Vol 36 (7) ◽  
pp. 645 ◽  
Author(s):  
Dennis H. Greer ◽  
Sylvie M. Sicard
Keyword(s):  
Vitis Vinifera ◽  
Carbon Balance ◽  
Dry Matter ◽  
Biomass Accumulation ◽  
Net Photosynthesis ◽  
Vitis Vinifera L ◽  
Controlled Environment ◽  
Allometric Relationships ◽  
High Demand ◽  
Carbon Economy

Assessing the impacts of environmental stresses on plant growth and productivity requires an understanding of the growth processes and the carbon economy that underpins this growth. Potted grapevines of the Vitis vinifera L. cv. Semillon were grown in a controlled environment and canopy growth; leaf, bunch and stem extension and net photosynthesis were routinely measured from budbreak to harvest. Allometric relationships enabled dry matter to be determined and, with net photosynthesis, used to determine the shoot carbon economy. Stems, leaves and bunches all followed a sigmoid growth pattern with leaves and stems allocated similar amounts of biomass and carbon while bunches had twice as much. Rates of carbon sequestered as biomass exceeded rates of carbon acquisition through net photosynthesis for over 25 days after budbreak. Despite the high demand for biomass in bunch growth, rates of carbon sequestration actually declined and overall, the vines maintained a positive carbon balance throughout the period of bunch growth. The Semillon shoots relied on carbon reserves to commence growth then produced a 53% carbon surplus after leaf (9%), stem (10%) and bunch (28%) growth demands were satisfied. This suggests these vines also allocated carbon to reserves to sustain the next season’s growth.

Effects of Plant Density and Thinning on High-Yielding Dry Beans (Phaseolus vulgaris) in Mexíco

1977 ◽  
Vol 13 (4) ◽  
pp. 325-335 ◽  
Author(s):  
Aguilar M. Immer ◽  
R. A. Fischer ◽  
Joshue Kohashi S.
Keyword(s):  
Phaseolus Vulgaris ◽  
Leaf Area ◽  
Seed Weight ◽  
Plant Density ◽  
Plant Competition ◽  
Growth And Yield ◽  
Positive Relation ◽  
Dry Beans ◽  
Leaf Area Duration ◽  
Pod Number

SUMMARYThe influence of leaf area and inter-plant competition on the growth and yield of a crop of high-yielding dry beans (Phaseolus vulgaris L.) in central Mexico was studied, using density and thinning treatments. The highest seed yield (4210 kg/ha at 14% moisture) was obtained with the highest density (28·8 plants/m2). Thinning showed that pods/plant was sensitive to inter-plant competition between 36 and 78 days after seeding (first flower at 50 days), but seeds/pod, and especially seed weight, were not sensitive. It is suggested that the close positive relation between yield and leaf area duration derives from the influence of photosynthate supply upon pod number.

scholarly journals Heritability of peach tree resistance to bacterial leaf spot

2017 ◽  
Vol 52 (5) ◽  
pp. 366-369 ◽  
Author(s):  
André Luiz Varago ◽  
Idemir Citadin ◽  
Marcos Robson Sachet ◽  
Gener Augusto Penso ◽  
Maria do Carmo Bassols Raseira
Keyword(s):  
Leaf Area ◽  
Disease Severity ◽  
Leaf Spot ◽  
Field Conditions ◽  
Broad Sense Heritability ◽  
Peach Tree ◽  
Bacterial Leaf Spot ◽  
Tree Resistance ◽  
Leaf Area Duration ◽  
Xanthomonas Arboricola

Abstract: The objective of this work was to evaluate the broad-sense heritability reaction to bacterial leaf spot (Xanthomonas arboricola pv. pruni), in peach tree populations obtained from directed crosses. Disease severity and defoliation of the genotypes were evaluated in field conditions, with posterior measurement of the healthy leaf area duration (HAD). The observed average heritability (0.51) indicates that the use of the evaluated genitors can be effective for the development of cultivars with higher resistance to the disease.

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