Sucrose accumulation in sugarcane is influenced by temperature and genotype through the carbon source - sink balance

2010 ◽  
Vol 61 (2) ◽  
pp. 111 ◽  
Author(s):  
N. G. Inman-Bamber ◽  
G. D. Bonnett ◽  
M. F. Spillman ◽  
M. H. Hewitt ◽  
D. Glassop
Keyword(s):  
Water Stress ◽  
Molecular Techniques ◽  
Clonal Variation ◽  
Sink Strength ◽  
Extension Rate ◽  
Cool Temperature ◽  
Sucrose Accumulation ◽  
Temperature Regimes ◽  
New Research ◽  
Source Sink

While substantial effort has been expended on molecular techniques in an attempt to break through the apparent ceiling for sucrose content (SC) in sugarcane stalks, molecular processes and genetics limiting sucrose accumulation remain unclear. Our own studies indicate that limiting expansive growth with water stress will enhance sucrose accumulation in both low- and high-sucrose clones. Sucrose accumulation was largely explained (72%) by an equation with terms for photosynthesis, plant extension rate (PER), and plant number. New research was conducted to determine if this simple model stands when using temperature rather than water stress to perturb the source–sink balance. We also applied a thinning treatment to test the proposal implicit in this equation that SC will increase if competition between plants for photo-assimilate is reduced. Four clones from a segregating population representing extremes in SC were planted in pots and subjected to warm and cool temperature regimes in a glasshouse facility. A thinning treatment was imposed on half the pots by removing all but 6 shoots per pot. Temperature as a means of reducing sink strength seemed initially to be more successful than water regime because PER was 43% lower in the cool than in the hot regime while photosynthesis was only 14% less. PER was a good indicator of dry matter allocation to expansive growth, limited by water stress but not by temperature, because stalks tended to thicken in low temperature. Thinning had little effect on any of the attributes measured. Nevertheless the clonal variation in plant numbers and the response of PER to temperature helped to explain at least 69% of the variation in sucrose accumulation observed in this experiment. Thus the earlier model for sucrose accumulation appeared to be valid for the effect on sucrose accumulation of both temperature and water stress on the source–sink balance. The next step is to include internodes in models of assimilate partitioning to help understand the limiting steps in sucrose accumulation from the basics of source–sink dynamics.

Increasing sucrose accumulation in sugarcane by manipulating leaf extension and photosynthesis with irrigation

2008 ◽  
Vol 59 (1) ◽  
pp. 13 ◽  
Author(s):  
N. G. Inman-Bamber ◽  
G. D. Bonnett ◽  
M. F. Spillman ◽  
M. L. Hewitt ◽  
J. Jackson
Keyword(s):  
Water Stress ◽  
Genotypic Variation ◽  
Biomass Accumulation ◽  
Mass Gain ◽  
Extension Rate ◽  
Total Biomass ◽  
Potted Plants ◽  
Tall Plant ◽  
Sucrose Storage ◽  
Source Sink

High sucrose content (SC) in sugarcane stalks is a priority for all sugarcane industries world wide. Partitioning to sucrose in the cane stalk is related to the supply of photo-assimilate and the demand for assimilate by other organs. If photosynthesis could be maintained, but leaf and stalk growth constrained, by genetics or management during the stalk elongation phase, it may be possible to reduce stalk height and to increase both SC and sucrose yield. This paper reports an experiment designed to test this hypothesis and to develop a methodology to assess variation in response to source–sink manipulation in sugarcane clones. The research was conducted on a ‘low’ (Q138) and a ‘high’ (Q183) SC cultivar in two temperature controlled and airtight glasshouses (chambers) at CSIRO’s Davies Laboratory in Townsville, Australia. Potted plants of each cultivar were placed in two chambers of the Tall Plant Facility (TPF). In one chamber, plants were irrigated to minimise water stress while plants in the other chamber were irrigated to reduce plant extension rate (PER) considerably more than photosynthesis. Water stress reduced gain in total biomass by 19% and gain in top mass by 37%, and increased sucrose mass gain by 27%. During the experiment, SC of dry matter increased 37% in the dry treatment and only 8% in the wet treatment and this effect was greater in Q183 than in Q138. Water stress reduced whole plant photosynthesis by 18%, thus largely accounting for the 19% reduction in biomass accumulation and it reduced PER by 41%, corresponding to the 37% reduction in mass of tops. Reduced PER resulted in reduced demand for photo-assimilate by fibre and tops thus allowing excess assimilate to accumulate in the form of sucrose. The techniques developed here to control PER and measure the resulting changes in carbon partitioning now allow further examination of both the control of the balance between growth and sucrose storage and the extent of genotypic variation to the response of reduced PER.

Sink strength of citrus rootstocks under water deficit

2021 ◽  
Author(s):  
Simone F da Silva ◽  
Marcela T Miranda ◽  
Vladimir E Costa ◽  
Eduardo C Machado ◽  
Rafael V Ribeiro
Keyword(s):  
Plant Growth ◽  
Root Growth ◽  
Water Deficit ◽  
Carbon Allocation ◽  
Sink Strength ◽  
Rangpur Lime ◽  
Carbon Supply ◽  
Valencia Orange ◽  
Source Sink ◽  
Orange Trees

Abstract Carbon allocation between source and sink organs determines plant growth and is influenced by environmental conditions. Under water deficit, plant growth is inhibited before photosynthesis and shoot growth tends to be more sensitive than root growth. However, the modulation of source-sink relationship by rootstocks remain unsolved in citrus trees under water deficit. Citrus plants grafted on Rangpur lime are drought tolerant, which may be related to a fine coordination of the source-sink relationship for maintaining root growth. Here, we followed 13C allocation and evaluated physiological responses and growth of Valencia orange trees grafted on three citrus rootstocks (Rangpur lime, Swingle citrumelo and Sunki mandarin) under water deficit. As compared to plants on Swingle and Sunki rootstocks, ones grafted on Rangpur lime showed higher stomatal sensitivity to the initial variation of water availability and less accumulation of non-structural carbohydrates in roots under water deficit. High 13C allocation found in Rangpur lime roots indicates this rootstock has high sink demand associated with high root growth under water deficit. Our data suggest that Rangpur lime rootstock used photoassimilates as sources of energy and carbon skeletons for growing under drought, which is likely related to increases in root respiration. Taken together, our data revealed that carbon supply by leaves and delivery to roots are critical for maintaining root growth and improving drought tolerance, with citrus rootstocks showing differential sink strength under water deficit.

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

Postanthesis green area duration in a semidwarf and a standard-height wheat cultivar as affected by sink strength

1994 ◽  
Vol 45 (7) ◽  
pp. 1337 ◽  
Author(s):  
GA Slafer ◽  
R Savin
Keyword(s):  
Grain Growth ◽  
Seedling Emergence ◽  
Grain Filling ◽  
Grain Weight ◽  
Soluble Carbohydrates ◽  
Sink Strength ◽  
Green Area ◽  
Ca 50 ◽  
Source Sink ◽  
The University

Postanthesis green area duration (GAD) has been associated frequently with yield. The senescence pattern of green organs is a major component of GAD. It has been proposed that delayed or accelerated senescence is strongly controlled by environmental conditions and the level of source or sink limitation on grain growth. In particular, it has been generally reported that the removal of reproductive structures delays the senescence process. However, results reporting this effect in wheat are not conclusive. A field experiment was conducted at the experimental station of The University of Melbourne comprising a factorial combination of a semidwarf and a standard-height wheat, and two levels of sink strength. At anthesis, 20 main shoots were tagged and detillered. Ten days after anthesis all the spikelets from one side of 10 tagged ears were removed by hand. The experiment was performed under natural, and 3 h-extended photoperiods from seedling emergence to heading. The photoperiod treatments induced differing grain filling environments and differing plant characteristics at onset of grain filling. Green area senescence was similar for both sink size treatments at any combination of cultivar and grain filling condition, indicating that the dynamics of plant senescence was insensitive to a severe reduction in number of grains per spike. Therefore, GAD was not significantly affected by the reduction in sink strength. The number of grains per spike were reduced to ca. 50% due to trimming. Therefore, source-sink ratio was doubled, but no significant changes in individual grain weight were found. There was no relationship between GAD and individual grain weight, confirming that grain growth in field-grown wheat is not limited by the strength of the source. Alternatively, our results confirmed that field-grown wheat is sink-limited during grain filling and that the likely accumulation of soluble carbohydrates in leaves does not affect the onset or rate of senescence.

scholarly journals A review of the biology and genetics of sea lice

2006 ◽  
Vol 63 (7) ◽  
pp. 1304-1316 ◽  
Author(s):  
Karin Boxaspen
Keyword(s):  
Population Structure ◽  
North Atlantic ◽  
Developmental Stages ◽  
Management Strategies ◽  
Molecular Techniques ◽  
Sea Lice ◽  
Lepeophtheirus Salmonis ◽  
New Research ◽  
And Control

Abstract Studies of the biology of sea lice have been conducted from various perspectives for two decades. For Lepeophtheirus spp., most of the published literature has centred on the economically important Lepeophtheirus salmonis, while for Caligus spp., research has focused on a wider range of species. The most numerous species of Caligus in North Atlantic waters, however, is Caligus elongatus, which is also economically important to salmon farming. Since the last review by Pike, A. W., and Wadsworth, S. L. (1999. Sea lice on salmonids: their biology and control. Advances in Parasitology, 44: 234–337.), research on sea lice has developed considerably, including the application of genetic methods. This new research has focused on life history biology, studying developmental stages under different environmental conditions (e.g. temperature and salinity), behaviour, distribution and the dispersal of free-living stages, monitoring practices, population structure, and modelling. The results of this research have informed risk analyses and allowed the refinement of management strategies to reduce sea lice infestations in wild and farmed populations of anadromous salmonids. Molecular techniques have been used to describe population structure and identify differences in genetic characterization of geographically separate populations and population markers. Research has been initiated to understand the parasite–host relationship at a molecular level and to develop a vaccine against sea lice.

The effect of high temperature regimes or short periods of water stress on development of small fruiting saltana vines

1965 ◽  
Vol 16 (5) ◽  
pp. 817 ◽  
Author(s):  
D McEAlexander
Keyword(s):  
High Temperature ◽  
Water Stress ◽  
Shoot Growth ◽  
Fruit Set ◽  
Shoot Elongation ◽  
Night Temperature ◽  
Applied Water ◽  
Temperature Regimes ◽  
Controlled Environments ◽  
Maximum Temperatures

Poor fruit set of sultanas in the Murray Valley is sometimes attributed to excessively high temperatures around flowering time. Experiments with small fruiting sultana vines in pots suggest that water stress is the more important factor. Fruit set was significantly less when a 3-day period of water stress was imposed at flowering or 1, 2, or 4 weeks after flowering, but not when it was imposed 6 weeks after flowering. Three days with maximum temperatures above 45°C at or 1 week after flowering did not reduce fruit set when ample water was supplied. When controlled environments combining day temperatures between 21 and 30°C with night temperatures between 19 and 25° were used, no significant differences in fruit set were found, although shoot growth increased with increasing night temperature. Shoot elongation slowed down during periods of applied water stress but recovered, when the stress was ended, to a rate greater than that of plants which had not been stressed.

scholarly journals DROUGHT-TOLERANT MAIZE GENOTYPES INVEST IN ROOT SYSTEM AND MAINTAIN HIGH HARVEST INDEX DURING WATER STRESS

2017 ◽  
Vol 15 (3) ◽  
pp. 450
Author(s):  
RONIEL GERALDO AVILA ◽  
PAULO CESÁR MAGALHÃES ◽  
AMAURI ALVES DE ALVARENGA ◽  
ALYNE DE OLIVEIRA LAVINSKY ◽  
CLEIDE NASCIMENTO CAMPOS ◽  
...  
Keyword(s):  
Water Stress ◽  
Root System ◽  
Dry Weight ◽  
Carbon Partitioning ◽  
Gas Exchanges ◽  
Drought Tolerant ◽  
Shoot Ratio ◽  
Root Shoot Ratio ◽  
Maize Genotypes ◽  
Source Sink

ABSTRACT – Drought is considered the primary limitation to agriculture and, can reduce grain yield by up to 60%when occurs at pre-flowering in maize. In this context this research, aimed to understand the maize genotypes behaviorto drought management and carbon partitioning between grain production and structures to maintain hydration whensubmitted to drought. Maize genotypes tolerant (DKB390 and P30F35) and sensitive (BRS1010 and 2B710) to droughtwere grown in a greenhouse using two water conditions: irrigated and stressed. Water deficit was imposed atpre-flowering and maintained for twelve days. Leaf water potential, gaseous exchange and male and female floweringinterval were evaluated. At the end of the cycle, production components and root/shoot ratio dry weight were evaluated.Drought-tolerant genotypes used root system as a mechanism of tolerance to drought, which ensure greater efficiencyin absorption and loss of water and, consequently, greater stomatal conductance during the drought, compared to thesensitive-genotypes. In addition, drought-tolerant genotypes showed greater stability in the source-sink relationship,exhibiting higher photosynthetic rate and harvest index.Keywords: water stress, carbon partitioning; root/shoot ratio dry weight, gas exchanges, Zea mays.GENÓTIPOS DE MILHO TOLERANTES À SECA INVESTEM EM SISTEMA RADICULARE MANTEM ALTO ÍNDICE DE COLHEITA DURANTE O ESTRESSE HÍDRICORESUMO- A seca é considerada restrição primária à agricultura, e no milho, quando ocorre no pré-florescimento,pode reduzir o rendimento de grãos em até 60%. Neste contexto, objetivou-se entender como genótipos de milhocontrastantes para tolerância à seca, gerenciam o particionamento de carbono entre produção de grãos e estruturasde manutenção da hidratação durante a seca. Para isso, em casa de vegetação cultivaram-se genótipos de milhotolerantes (DKB390 e P30F35) e sensíveis (BRS1010 e 2B710) à seca, em duas condições hídricas: irrigadonormal e déficit hídrico. No pré-florecimento foi imposto o déficit hídrico, que foi mantido por doze dias.Posteriormente avaliou-se o potencial hídrico foliar, trocas gasosas e intervalo de florescimento masculino e feminino.No final do ciclo, avaliaram-se os componentes de produção e a razão raiz/parte aérea. Constatou-se que, genótipostolerantes utilizaram preferencialmente sistema radicular como um mecanismo de tolerância à seca, o que garantiu aesses genótipos, maior eficiência entre a absorção e perda de água e, consequentemente, maior condutância estomáticadurante a seca, em relação aos genótipos sensíveis. Além disso, os genótipos tolerantes apresentaram maior equilíbrioem suas relações fonte e dreno, exibindo maiores taxa fotossintética e índice de colheita.Palavras-chave: estresse hídrico, particionamento de carbono, razão raiz/parte aérea, trocas gasosas, Zea mays.                                                     

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