Genotypic Variation in Relative Growth Rate and Carbon Isotope Discrimination in Sunflower Is Related to Photosynthetic Capacity

1996 ◽  
Vol 23 (2) ◽  
pp. 227 ◽  
Author(s):  
JM Virgona ◽  
DG Farquhar
Keyword(s):  
Growth Rate ◽  
Carbon Isotope ◽  
Relative Growth Rate ◽  
Carbon Isotope Discrimination ◽  
Photosynthetic Capacity ◽  
Genotypic Variation ◽  
Wild Accession ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Isotope Discrimination

A previous study showed that carbon isotope discrimination (Δ) was negatively related to transpiration efficiency (W, the ratio of dry matter accumulation to transpiration) and biomass accumulation amongst sunflower (Helianthus annuus L.) genotypes. Three experiments which explore the physiological basis of relationships between Δ, relative growth rate (RGR) and leaf gas exchange characteristics are reported. Growth was analysed on seven genotypes during the early vegetative stage (up to 31 days after emergence). Carbon isotope discrimination, Δ, W, and photosynthetic CO2 assimilation rate per unit leaf area (A) at ambient concentration of CO2 were measured on plants that made up the final harvest. Six of the seven genotypes were also grown under a low nitrogen (N) regime and harvested at 30 days after emergence. Carbon isotope discrimination was negatively related to relative growth rate (RGR), net assimilation rate (NAR) and photosynthetic rate per unit area, which in turn, were all positively correlated with each other. Genotypic variation inA (51%) was greater than that in leaf conductance, g (32%) and there was no relationship between g and Δ. Under the low N regime, A and g declined by 33 and 12%, respectively, across all genotypes producing a significant rise in A of 1.10. In a second experiment, growth analysis on 13 cultivated forms of H. annuus, a wild accession and a H. argophyllus accession, also showed that there was a positive relationship between RGR and NAR, and that both growth indices were negatively related to Δ. In a further experiment, using 14 genotypes (including the wild accession) there was a highly significant negative correlation (r = -0.85, P < 0.001) between photosynthetic capacity, measured using an oxygen electrode, and Δ. These results indicate that variation in photosynthetic capacity can account for genotypic variation in both Δ and RGR during vegetative growth in sunflower. Hence, faster growing sunflower genotypes have higher rates of photosynthesis and use water more efficiently.

Variation in transpiration efficiency and carbon isotope discrimination in cowpea

1999 ◽  
Vol 26 (6) ◽  
pp. 503 ◽  
Author(s):  
Ashok ◽  
I. S. Aftab Hussain ◽  
T. G. Prasad ◽  
G. C. Wright ◽  
M. Udaya Kumar ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Negative Correlation ◽  
Field Experiments ◽  
Carbon Isotope Discrimination ◽  
Genotypic Variation ◽  
Net Assimilation Rate ◽  
Transpiration Efficiency ◽  
Assimilation Rate ◽  
Isotope Discrimination ◽  
Net Assimilation

Genotypic variation in transpiration efficiency (TE) was investigated in a set of cowpea (Vigna unguiculata (L.) Walp.) genotypes grown as isolated plants in pots and under canopy conditions in the field. In the field, plants were grown in mini-lysimeters embedded in the ground around which a crop was grown, to simulate crop canopy condition. Two moisture regimes (100 and 60% of field capacity) were imposed from 30 to 60 days after sowing in both pot and field experiments. TE was determined by measuring transpiration and dry matter (DM) produced by the genotypes during the treatment period. Genotypes differed significantly in DM although the variation in the amount of water transpired (T) was relatively small. The TE ranged from 2.2 to 3.7 g kg–1, representing a significant genotypic and environmental effect on the variation. There was a significant negative correlation (r = –0.77, P<0.01) between TE adjusted for prevailing vapour pressure deficit and carbon isotope discrimination ratio (Δ) across all the experiments and treatments. A significantly positive correlation of TE measured in pot and field experiments suggested a low G x E interaction. There was a negative correlation (r = –0.62, P < 0.01) between T and TE while the correlation of TE with net assimilation rate was non-significant, suggesting that the major cause for variation of TE in cowpea was in general associated with stomatal rather than mesophyll factors. Because of the positive relationship between T and DM, and negative relationship between TE and T, selection for high TE might therefore be associated with reduced T and hence lower DM. However, the present investigation showed a possibility of identifying specific genotypes with a combination of high TE and high net assimilation rate. The genotypes with high TE and high net assimilation rates were able to produce high DM under moisture deficit conditions.

scholarly journals Influence of Soil Amendment on the Relative Growth Rate and Net Assimilation Rate of Phaseolus vulgaris and Vigna aconitifolia

2020 ◽  
pp. 1-13
Author(s):  
E. A. Effa ◽  
A. A. J. Mofunanya ◽  
B. A. Ngele
Keyword(s):  
Growth Rate ◽  
Phaseolus Vulgaris ◽  
Relative Growth Rate ◽  
Soil Amendment ◽  
Dry Weight ◽  
Organic Manure ◽  
Assimilation Rate ◽  
Vigna Aconitifolia ◽  
Relative Growth ◽  
Net Assimilation

Background: Soil pH is one of the most important factors that contribute to crop growth and productivity. The present research was designed to assess the influence of soil amendment using organic manure and agricultural lime on the relative growth rate (RGR) and net assimilation rate (NAR) of Phaseolus vulgaris and Vigna aconitifolia grown on soils from different locations. Methodology: The three locations were: Akamkpa, Calabar Municipality and Odukpani. The pH for the three soil locations were 4.0, 7.0 and 9.0, respectively. The treatments were; control (0 g), OM1 (100 g organic manure), OM2 (200 g organic manure), AL1 (100 g agricultural lime), AL2 (200 g agricultural lime), OM1 + AL1 (50 g organic manure + 50 g agricultural lime) and OM2 +AL2 (100 g organic manure and 100 g agricultural lime). Results: Results obtained on the RGR of the leaf dry weight of P. vulgaris treated with OM2 was the highest (0.50 g/wk) followed by OM1 (0.41 g/wk). OM1 + AL1 had the highest RGR of the stem dry weight of P. vulgaris grown on soil from Calabar Municipality. In the RGR of the root dry weight, OM2 had the highest mean value in both plants grown on Akamkpa soil. Results obtained at 4 weeks after planting (WAP) revealed that there was significant (P<0.05) increase in NAR of plants grown on soil from Akamkpa. The highest NAR was obtained for V. aconitifolia treated with OM2 (0.0447 g/wk) followed by OM2 + AL2 (0.0057 g/wk) for both V. aconitifolia and P. vulgaris. P. vulgaris grown on Akamkpa and Odukpani soils treated with AL2 (0.0032 g/wk), OM1 + AL1 (0.0041 g/wk) and OM2+ AL2 (0.0062 g/wk) had the highest NAR at 8 WAP. Conclusion: The RGR and NAR of the two bean varieties were improved following treatments with organic manure and agricultural lime.

Genetic Variation in the Effects of Root Impedance on Growth and Transpiration Rates of Wheat and Barley

1992 ◽  
Vol 19 (2) ◽  
pp. 109 ◽  
Author(s):  
J Masle
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Time Course ◽  
Net Assimilation Rate ◽  
Root Penetration ◽  
Lower Sensitivity ◽  
Soil Resistance ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Net Assimilation

Genotypes of wheat and barley, including modern and landrace lines, were compared in their response to soil resistance to root penetration during the early vegetative phase (up to 5 leaf stage). All genotypes exhibited reduced growth and transpiration rates at high soil resistance, but there was large variation in the magnitude and time course of these effects and in the mechanisms underlying the growth reduction (changes in net assimilation rate, carbon partitioning within the plant, relative effects of leaf primordia development, versus growth of expanding leaves). Similar wide ranges of responses were observed among landrace and modern wheats. In both wheat and barley, the genotypes with lower sensitivity to soil resistance, in terms of relative growth rate, were those with the slowest net assimilation rate and root growth rate at low soil resistance, and those for which carbon allocation to the impeded roots, relative to the shoot, was significantly increased, to the extent that root relative growth rate even became greater (in terms of mass, not of length) than on loose soil. For a number of genotypes, growth was slowed down throughout the experiment whereas for others it was reduced only during the first few days following germination. In contrast, transpiration rate was at all stages lower at high than at low soil resistance. This indicates that the effects of soil resistance to root penetration on stomatal conductance involve different controls - or different sensitivities to a common signal - from those operating on cell division and expansion.

Determination of Effective Method of NPK Fertilization in Pea (Pisum sativum L.) Cultivars Grown in Pakistan

2020 ◽  
Author(s):  
Khalid Hussain ◽  
Muniza Sarfraz ◽  
Khalid Nawaz ◽  
Ghulam Yasin ◽  
Zhide Geng ◽  
...  
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Antioxidant Activities ◽  
Foliar Spray ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Soil Application ◽  
Net Assimilation ◽  
Growth Quality ◽  
Npk Fertilization

Background: Nitrogen, phosphorus and potassium (NPK) are amongst the fundamental macronutrients, which are crucial for the growth and development plants. There is lack of information for the most effective method for NPK fertilization in pea cultivars grown in Pakistan. In most of the cases, NPK is applied as soil application rather than foliar spray. Methods: Experiments were conducted to find out the most effective method of NPK fertilization i.e. soil application or foliar spray on three pea cultivars (Aleena, Climax and Meteor). Experiment was arranged in a completely randomized design with 4 replicates and data was recorded at different growth stages. Result: Soil and foliar spray of NPK showed significant results for the enhancement of root and shoot development, foliage growth, relative growth rate (RGR), net assimilation rate (NAR), photosynthetic pigments, total carbohydrate contents and soluble proteins. Antioxidant activities i.e. catalases (CAT), peroxidase (POD) and yield attributes increased significantly with NPK applications. NPK foliar application showed better result only for the higher relative growth rate (RGR) and net assimilation rate (NAR). It was noted that NPK soil applications were more effective for the improvement of growth, quality and yield of pea as compared to foliar spray. Climax and Aleena cultivars were better in relation to growth, quality and yield than Meteor with soil NPK application. Changes in antioxidant activities by NPK significantly increased the defense mechanism in plants resulted improved in plant metabolism that increased the growth, yield and quality of pea. It was concluded that soil application of NPK was more effective for higher productivity of pea than foliar use.

Genetic variation for leaf carbon isotope discrimination and its association with transpiration efficiency in canola (Brassica napus)

2020 ◽  
Vol 47 (4) ◽  
pp. 355
Author(s):  
Shek M. Hossain ◽  
Josette Masle ◽  
Andrew Easton ◽  
Malcolm N. Hunter ◽  
Ian D. Godwin ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Genotypic Variation ◽  
Dry Weight ◽  
Transpiration Efficiency ◽  
Isotope Discrimination ◽  
Leaf Chlorophyll ◽  
Total Dry Weight ◽  
Positive Correlations

Drought is a major constraint to canola production around the world. There is potential for improving crop performance in dry environments by selecting for transpiration efficiency (TE). In this work we investigated TE by studying its genetic association with carbon isotope discrimination (Δ) and other traits, e.g. specific leaf weight (SLW) and leaf chlorophyll content (SPAD). Among the 106 canola genotypes – including open-pollinated, hybrid, inbred types and cytoplasmic variants – tested in the field and glasshouse there was significant genotypic variation for TE, Δ, plant total dry weight, SLW and SPAD. Strong negative correlations were observed between TE and Δ (–0.52 to –0.76). Negative correlations between Δ and SLW or SPAD (–0.43 to –0.78) and smaller but significant positive correlations between TE and SLW or SPAD (0.23 to 0.30) suggested that photosynthetic capacity was, in part, underpinning the variation in TE. A cytoplasmic contribution to genetic variation in TE or Δ in canola was also observed with Triazine tolerant types having low TE and high Δ. This study showed that Δ has great potential for selecting canola germplasm with improved TE.

scholarly journals Growth of marandu palisadegrass subjected to strategies of intermittent stocking

2009 ◽  
Vol 66 (6) ◽  
pp. 733-741 ◽  
Author(s):  
Alessandra Aparecida Giacomini ◽  
Sila Carneiro da Silva ◽  
Daniel Oliveira de Lucena Sarmento ◽  
Cauê Varesqui Zeferino ◽  
Salim Jacaúna Souza Júnior ◽  
...  
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Relative Growth Rate ◽  
Weight Ratio ◽  
Crop Growth ◽  
Net Assimilation Rate ◽  
Assimilation Rate ◽  
Relative Growth ◽  
Crop Growth Rate ◽  
Net Assimilation

Grazing strategies alter sward leaf area patterns of growth, affecting herbage accumulation and utilisation. The objective of this experiment was to evaluate the growth of marandu palisadegrass (Brachiaria brizantha cv. Marandu) swards subjected to strategies of intermittent stocking. The experiment was carried out in Piracicaba, São Paulo, Brazil, from October/2004 to September/2005. Swards were grazed at 95 and 100% canopy light interception (LI) to post-grazing heights of 10 and 15 cm, following a 2 × 2 factorial arrangement with four replications in a randomised complete block design. The response variables evaluated were: crop growth rate, relative growth rate, net assimilation rate, leaf area ratio and leaf weight ratio. In early and late spring, the highest crop growth rate was recorded for treatment 95/15 (11.2 and 10.1 g m-2 day-1, respectively), along with high values of net assimilation rate (4.4 and 6.9 g m-2 day-1, respectively), leaf area ratio (0.0095 and 0.0103 m-2 g-1, respectively) and leaf weight ratio (0.56 and 0.56 g g-1, respectively). To compensate reductions in net assimilation rate plants made some morphological and physiological adjustments increasing leaf area and leaf weight ratio. Relative growth rate and net assimilation rate were 26 and 50% higher, respectively, on swards grazed at 95% than at 100% LI. In early spring treatments 100/10 and 95/15 resulted in the highest relative growth rate (0.086 and 0.059 g m-2 day-1, respectively). Treatment 95/15 resulted in the most favourable pattern of growth (crop growth rate, relative growth rate, net assimilation rate), particularly during the transition period between winter and spring.

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