A Review of Evidence on the Control of Shoot: Root Ratio, in Relation to Models

Wilson, J. Bastow

doi:10.1093/oxfordjournals.aob.a087575

Cited by 584 publications

(394 citation statements)

References 159 publications

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“…Most studies, however, were conducted on alpine grasslands with a variable degree of degradation; the value found in this study is comparable to the mean of non-degraded Kobresia grasslands (R/S: 20.3, Li and others 2008). The high R/S ratios in alpine Kobresia grasslands were reported to be mainly driven by environmental conditions such as a low annual mean temperature, low N-availability, and grazing pressure (Davidson 1969;Wilson 1988;Gao and others 2007;Li and others 2008). We suggest that K. pygmaea optimizes C-allocation to minimize resource limitation, which presumably explains the high R/S ratios of 20.0.…”

Section: Implications For a Vulnerable Grassland Ecosystemmentioning

confidence: 99%

Nitrogen Uptake in an Alpine Kobresia Pasture on the Tibetan Plateau: Localization by 15N Labeling and Implications for a Vulnerable Ecosystem

et al. 2015

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Grasslands are very important regionally and globally because they store large amounts of carbon (C) and nitrogen (N) and provide food for grazing animals. Intensive degradation of alpine grasslands in recent decades has mainly impacted the upper root-mat/soil horizon, with severe consequences for nutrient uptake in these nutrient-limited ecosystems. We used 15 N labeling to identify the role of individual soil layers for N-uptake by Kobresia pygmaea-the dominating plant in the degraded Tibetan pasture ecosystems. We hypothesized a very efficient N-uptake corresponding mainly to the vertical distribution of living roots (topsoil > subsoil). We assume that K. pygmaea develops a very dense root-mat, which has to be maintained by small aboveground biomass, to enable this efficient N-uptake. Consequently, a higher N-investment into roots compared to shoots was hypothesized. The 15 N recovery in whole plants ($70%) indicated very efficient N-uptake from the upper injection depths (0-5 cm). The highest 15 N amounts were recovered in root biomass, whereby 15 N recovery in roots strongly decreased with depth. In contrast, 15 N recovery in shoots was generally low ($18%) and independent of the 15 N injection depth. This clearly shows that the low N demand of Kobresia shoots can be easily covered by N-uptake from any depth. Less living root biomass in lower versus upper soil was compensated by a higher specific activity of roots for N-uptake. The 15 N allocation into roots was on average 1.7 times higher than that into shoots, which agreed well with the very high R/S ratio. Increasing root biomass is an efficient strategy of K. pygmaea to compete for belowground resources at depths and periods with available resources. This implies high C-costs to maintain root biomass ($6.0 kg DM m -2 ), which must be covered by a very low amount of photosynthetically active shoots (0.3 kg DM m -2 ). It also suggests that Kobresia grasslands react extremely

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Section: Implications For a Vulnerable Grassland Ecosystemmentioning

confidence: 99%

Nitrogen Uptake in an Alpine Kobresia Pasture on the Tibetan Plateau: Localization by 15N Labeling and Implications for a Vulnerable Ecosystem

et al. 2015

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“…Modifying influences of drought stress on the DM partitioning were shown for many plant species (Cruz et al 1986, Huck et al 1986, Schulze 1986, Li et al 1994. Drought stress thereby mostly reduces leaf growth and increased at least relative dry matter allocation into the root, leading to shoot/root decrease ratio (Brouwer 1983, Wilson 1988, Setter 1990.…”

Section: Introductionmentioning

confidence: 99%

Effects of varied water regimes on root length, dry matter partitioning and endogenous plant growth regulators in sunflower (Helianthus annuusL.)

Rauf

Sadaqat

2007

Journal of Plant Interactions

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A field experiment was conducted to quantify the effect of varied water regimes on root length, partitioning of dry matter and plant growth regulators by using sunflower genotypes differing in maturity and drought tolerance. Significant depressing effect of drought stress was evident on traits (i.e., reproductive dry matter, leaf area index and cytokinin concentrations in leaves). However, root/shoot, reproductive/vegetative ratios and Abscisic acid (ABA) concentration were found to increase under drought stress. Drought stress also changed the dry matter accumulation pattern of genotypes. In most cases it reduced the days to reach the maximum peak showing early senescence. ABA was identified as a multi-functional plant growth regulator under drought stress, causing early senescence of plants and translocation of assimilates to the roots and reproductive part while root growth under drought stress was explained by the indole-acetic acid (IAA) concentrations. Maintaining higher cytokinin contents were involved in accumulation of higher reproductive dry matter under drought stress. Although ABA and IAA were both involved in the development of defense responses during the adaptation and survival to drought stress but higher productivity under drought stress was only realized through maintaining higher cytokinin contents.

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“…This could be seen in the root/top ratio where the values decreased with the increasing strength of the nutrient solution. Normally the root/top ratio is high when a nutrient is missing (Wilson 1988), but a few tree species like Pinus sp. and Acer rubrum were indifferent to increasing the level of nutrients on the substratum, when six nitrogen levels were tested: 10, 25, 50, 100, 200 and 400 ppm (Vaitkus et al 1993).…”

Section: Discussionmentioning

confidence: 99%

“…It is well-known that in nutrient deficient soils there is higher allocation of matter to the roots than to the tops (Mooney 1972, Chapin 1980 leading to a high root/top ratio (Wilson 1988). Increased nutrient level causes the root/top ratio to decrease but the growth patterns are different from species to species (Vaitkus et al 1993).…”

Section: Introductionmentioning

confidence: 99%

Response of Dalbergia miscolobium Benth. seedlings, a cerrado tree species, to mineral nutrient supply

Sassaki¹,

Felippe²

1998

Rev. bras. Bot.

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-(Response of Dalbergia miscolobium Benth. seedlings, a cerrado tree species, to a mineral nutrient supply). The soil under the Brazilian cerrado vegetation is very poor in nutrients. The aim of this study was to investigate the effect of the addition of a nutrient solution in the early growth of D. miscolobium, a typical cerrado tree species, cultivated in cerrado soil. Seeds were germinated in Petri dishes and seven-day old seedlings were transfered to pots containing cerrado soil. These were supplied once a week with a normal, 1/2 or 1/10 strength nutrient solution. Four growth analysis were done over a period of 145 days from seed imbibition, in terms of dry mass, leaf area and carbohydrate and nitrogen contents. Other derived parameters were also analysed. The addition of a nutrient solution promoted early growth with a preferential separation of dry matter towards the tops; in the control seedlings (no nutrient addition) more dry matter accumulated in the root system. This suggests a preferential investment in root growth in poor soils such as the cerrado ones. Reliable evidence of this is given by the level of carbohydrate and protein which was higher in the roots than in the tops of plants growing in cerrado soil without the addition of nutrients.RESUMO -(Resposta das plântulas de Dalbergia miscolobium Benth., uma espécie arbórea de cerrado, à adição de nutrientes minerais). O solo sob vegetação do cerrado brasileiro é muito pobre em nutrientes. O objetivo deste trabalho foi o estudo do efeito da adição de solução nutritiva sobre o crescimento inicial de D. miscolobium, uma espécie arbórea nativa do cerrado, cultivada em solo de cerrado. As sementes foram germinadas em placas de Petri e plântulas com sete dias foram transferidas para recipientes contendo solo de cerrado. Estas foram supridas, uma vez por semana, com solução nutritiva normal, diluída duas vezes ou diluída 10 vezes. Quatro análises de crescimento foram feitas por um período de 145 dias desde o início da embebição das sementes, em termos de massa de matéria seca, área foliar e conteúdo de carboidratos e de nitrogênio. Outros parâmetros derivados também foram avaliados. A adição da solução nutritiva promoveu o crescimento inicial com partição preferencial de matéria seca para a parte aérea; nas plântulas controle (sem adição de nutrientes) mais matéria seca foi acumulada no sistema radicular. Isto sugere um investimento preferencial no crescimento da raiz em solos mais pobres como os de cerrado.Uma boa evidência sobre isso é dada pelo nível de carboidratos e proteínas, o qual foi maior nas raízes do que nas partes aéreas em plantas crescendo em solo de cerrado sem solução nutritiva.

show abstract

A Review of Evidence on the Control of Shoot: Root Ratio, in Relation to Models

Cited by 584 publications

References 159 publications

Nitrogen Uptake in an Alpine Kobresia Pasture on the Tibetan Plateau: Localization by 15N Labeling and Implications for a Vulnerable Ecosystem

Nitrogen Uptake in an Alpine Kobresia Pasture on the Tibetan Plateau: Localization by 15N Labeling and Implications for a Vulnerable Ecosystem

Effects of varied water regimes on root length, dry matter partitioning and endogenous plant growth regulators in sunflower (Helianthus annuusL.)

Response of Dalbergia miscolobium Benth. seedlings, a cerrado tree species, to mineral nutrient supply

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