The cost of stress: Dry matter partitioning changes with seasonal supply of water and nitrogen to dryland wheat

Hamblin, Ann; Tennant, D.; Perry, M. W.

doi:10.1007/bf02851909

Cited by 97 publications

(48 citation statements)

References 16 publications

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“…Although a higher recovery of 13 C was allocated in roots in the fenced plots than in the grazed plots, and higher spatial variability obscured the differences of 13 C allocation in roots between the two sites. Plants increased the recovery of 13 C in roots as a response to the shortage of nitrogen (Hamblin et al, 1990). We suggest that lower 13 C turnover in soil with lower nitrogen acquisition stimulated root growth for nitrogen absorption.…”

Section: Effect Of Exclosure On 13 C Dynamic and Allocationmentioning

confidence: 69%

Field 13CO2 pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a Kobresia meadow

Zou

Zhao

et al. 2014

Biogeosciences

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Abstract. Livestock exclosure has been widely used as an approach for grassland restoration. However, the effects of exclosures on grasslands are controversial and can depend on many factors, such as the grassland ecosystem types, evolutionary history and so on. In this study, we conduct field experiments to investigate the variations of the ecosystem function in response to livestock exclosure in a Kobresia humilis meadow with 6 years of grazing exclosure on the QinghaiTibetan Plateau. We focused on two ecosystem functions: plant community structure and ecosystem carbon cycling. The plant aboveground productivity, plant diversity and the composition of plant functional groups of the meadow were addressed as the indicators of the plant community structure. The 13 C isotope pulse labeling technique was applied to evaluate the alterations of ecosystem carbon cycling during a short term. The results showed that the plant community structure was changed after being fenced in for 6 years, with significantly decreased aboveground productivity, species loss and varied composition of the four plant functional groups (grasses, sedges, legumes and forbs). Using the pulse labeling technique, we found a lower cycling rate of 13 C in the plant-soil system of the fenced plots compared with the grazed sites during the first 24 h after labeling. A higher proportion of recovered 13 C in the plant-soil system migrated into the soil as root exudates immediately after labeling at both fenced and control grazed sites, with a significantly lower proportion in the fenced site, coinciding with the lower proportion of 13 C lost from soil respiration. Thirtytwo days after labeling, 37 % of the recovered 13 C remained in the soil of the fenced plots, with significant differences compared to in the grazed plots (47 %). In addition, less 13 C (5 vs. 7 %) was lost by soil respiration in the fenced plots during the chase period of 32 days. Overall, our study suggests that livestock exclosures have negative effects on the plant community structure and partitioning patterns of the photoassimilated carbon in the Kobresia meadow, and the effects on photoassimilated carbon cycling are likely to result from the variations of community structures in the ecosystem.

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Section: Effect Of Exclosure On 13 C Dynamic and Allocationmentioning

confidence: 69%

Field 13CO2 pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a Kobresia meadow

Zou

Zhao

et al. 2014

Biogeosciences

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“…Our values are also similar to values sampled to depths of 30 cm (11.8 in) and reported by Bolinder et al (1997) from sites in Ontario and Québec, Canada, of 0.14 and 0.2 for WW at two sites and where 70% of the root mass was found to a depth of 15 cm (5.9 in). In Saskatchewan, Canada, where sampling was done to depths of 60 cm (23.6 in), Campbell et al (1977) moderate temperatures and as high as 0.5 where nitrogen (N) and soil water were limiting factors, with a midrange value in the mid-0.2s (Bolinder et al 1997;Hamblin et al 1990). Still lower ratios of biomass have been reported for WW grown in Sweden (Kätterer et al 1993), with ratios at harvest of 0.04 to a depth of 50 cm (19.7 in) under rainfed conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Wheat root:shoot ratios as low as 0.1 in the surface 10 cm (3.9 in) have been reported under conditions of adequate soil water and Table 5 Phenologic development of root and crown mass for cereal grains and belowground stem and root mass for the 0 to 10 cm soil depth for all crops in 1993 and 1994 near Pendleton, Oregon. moderate temperatures and as high as 0.5 where nitrogen (N) and soil water were limiting factors, with a midrange value in the mid-0.2s (Bolinder et al 1997;Hamblin et al 1990). Still lower ratios of biomass have been reported for WW grown in Sweden (Kätterer et al 1993), with ratios at harvest of 0.04 to a depth of 50 cm (19.7 in) under rainfed conditions.…”

Section: Experiments Namementioning

confidence: 99%

Root:shoot ratios and belowground biomass distribution for Pacific Northwest dryland crops

Williams¹,

McCool²,

Reardon³

et al. 2013

Journal of Soil and Water Conservation

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Roots, cereal crowns, and stems growing beneath the soil surface provide important resistance to soil erosion. Understanding the amount and distribution of this material in the soil profile could provide insight into resistance to soil erosion by water and improve the performance of soil erosion models, such as the revised universal soil loss equation (RUSLE) and the water erosion prediction project (WEPP). Erosion models use built-in or external crop growth models to populate crop yield and live aboveground and associated belowground biomass databases. We examined two data sets from the dryland small grain production region in the Pacific Northwest of the United States to determine root:shoot ratios, the vertical distribution of root and attached belowground biomass, and incorporated residue from previously grown crops. Data were collected in 1993Data were collected in , 1994Data were collected in , 1995, and 2000 from short-term no-till and conventional tillage experiments conducted near Pendleton, Oregon, and Pullman, Washington, and in 1999 and 2000 from long-term experiments representative of farming practices near Pendleton, Oregon. The crops sampled in the short-term data set included soft white winter and spring wheat (Triticum aestivum L.; WW and SW, respectively), spring peas (Pisum sativum L.; SP), and winter canola (Brassica napus L.; WC). Crops sampled in the long-term study included WW, SW, and SP. Data were collected at harvest in both data sets and during three phenologic stages in each of the crops in the short-term data set. Soil samples were collected to a depth of 60 cm (23.6 in) in the short-term and 30 cm (11.9 in) in the long-term experiments. In both sets of measurements, we found greater than 70% of root mass is in the top 10 cm (3.9 in) of the soil profile with the exception of SP, which had 70% of root mass in the top 15 cm (5.9 in) of the soil profile. WC produced significantly more biomass near the soil surface than WW, SW, or SP. Root-to-shoot biomass ratios in mature wheat ranged from 0.13 to 0.17 in the top 30 cm (11.9 in) of the soil profile, substantially lower than values suggested for use in WEPP (0.25). In the long-term experiments, soil of the conventionally tilled continuous winter wheat (CWW) plots contained significantly greater biomass than soil of conventionally tilled winter wheat/fallow (CR) and no-till winter wheat/fallow (NT) treatments. There was no significant difference between CWW and conventionally tilled winter wheat/spring pea (WP); however, CWW returned more residue to the soil than WP because SP produced less residue and these residues were incorporated with a field cultivator rather than a moldboard plow. More accurate representation of root development, particularly in winter crops, could improve RUSLE and WEPP performance in the Pacific Northwest where winter conditions have proven difficult to model. Key words: canola-incorporated residue-peas-root mass-root-shoot ratio-wheatA Mediterranean climate of wet, cool winters and dry, hot summers h...

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“…Por exemplo, uma alta proporção de biomassa total em raízes pode não ser desejável, uma vez que as raízes são importantes órgãos consumidores de assimilados (Boogaard et al, 1996). Em trigo, cerca de 10% a 45% da biomassa total pode ser encontrada abaixo da superfície do solo, e, dependendo das condições do solo, 20 a 50% dos assimilados podem ser usados para o crescimento das raízes (Hamblin et al, 1991). Essa interpretação parece ser válida no presente caso, uma vez que a interação entre a inoculação e as doses e épocas de aplicação de N no acúmulo de massa seca determinada na antese (Tabela 2) não mais foi observada na maturação fisiológica (Tabela 3).…”

Section: Resultsunclassified

Realocação de nitrogênio e de biomassa para os grãos, em trigo submetido a inoculação de Azospirillum

Didonet

Lima²,

Candaten³

et al. 2000

Pesq. agropec. bras.

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The cost of stress: Dry matter partitioning changes with seasonal supply of water and nitrogen to dryland wheat

Cited by 97 publications

References 16 publications

Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow

Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow

Root:shoot ratios and belowground biomass distribution for Pacific Northwest dryland crops

Realocação de nitrogênio e de biomassa para os grãos, em trigo submetido a inoculação de Azospirillum

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The cost of stress: Dry matter partitioning changes with seasonal supply of water and nitrogen to dryland wheat

Cited by 97 publications

References 16 publications

Field &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a &lt;i&gt;Kobresia&lt;/i&gt; meadow

Field &lt;sup&gt;13&lt;/sup&gt;CO&lt;sub&gt;2&lt;/sub&gt; pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a &lt;i&gt;Kobresia&lt;/i&gt; meadow

Root:shoot ratios and belowground biomass distribution for Pacific Northwest dryland crops

Realocação de nitrogênio e de biomassa para os grãos, em trigo submetido a inoculação de Azospirillum

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Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow

Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow