Factors affecting Cyperus difformis seed germination and seedling emergence

Derakhshan, Abolfazl; Gherekhloo, Javid

doi:10.1590/s0100-83582013000400008

Cited by 15 publications

(26 citation statements)

References 24 publications

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“…Estimated T b values averaged 16.96 C, similar to those obtained by Pedroso et al (2019). However, this value is 2.15 C larger than that reported by Derakhshan and Gherekhloo (2013), which could be related to the model presented in this work being developed using a wider range of test temperatures (Bradford 2002). Variations within a species due to genetic diversity of ecotypes from separate geographic regions can also be expected (Baskin and Baskin 1998).…”

Section: Characterizing Germination Responses To Temperaturesupporting

confidence: 60%

ALS inhibitor–resistant smallflower umbrella sedge (Cyperus difformis) seed germination requires fewer growing degree days and lower soil moisture

et al. 2019

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The repetitive use of ALS inhibitors for smallflower umbrella sedge (Cyperus difformis L.) control has selected for herbicide-resistant (R) populations that threaten the sustainability of rice (Oryza sativa L.) production and demand alternative control measures be developed. A better understanding of seedling recruitment patterns at the field level is required to optimize the timing and efficacy of control measures. Therefore, a population-based threshold model was developed for optimizing germination prediction in multiple acetolactate synthase (ALS)-R and ALS-susceptible (ALS-S) C. difformis biotypes and applied to field-level emergence predictions. Estimated base temperatures (Tb) ranged from 16.5 to 17.6 C with no clear pattern between biotypes; such values are higher than Tb values of other important rice weeds, as well as for rice. Germination rates increased linearly from 16 to 33.7 C. ALS-R seeds germinate faster due to smaller median thermal times to germination (θT(50)) while also displaying lower germination synchronicity across water potentials. Interestingly, ALS-R biotypes were capable of germinating under lower moisture availability, as indicated by their lower (more negative) base water potential values (Ψb(50)) for seed germination; Ψb(50) values ranged from −0.24 to −1.13 MPa. In-field soil germination measurements found thermal times to emergence varied across three water regimes (daily water, flooded, or saturated). Seedling emergence under the daily water treatment was fastest; however, total seedling density was lower than for the other water regimes. In order to optimize springtime C. difformis seedling emergence, soil moisture should be kept around field capacity, as germination is hindered at lower moisture contents. By predicting when most of the seed population germinates, the thermal-time model can address issues regarding the optimal timing for herbicide applications, thereby allowing for improved C. difformis management in rice fields.

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Section: Characterizing Germination Responses To Temperaturesupporting

confidence: 60%

ALS inhibitor–resistant smallflower umbrella sedge (Cyperus difformis) seed germination requires fewer growing degree days and lower soil moisture

et al. 2019

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“…Another possible reason for reduced emergence with increasing depth could be hypoxia and low rates of gaseous diffusion at deeper depths (Benvenuti ). The decreased seedling emergence from increased burial depth has been reported in several weed species, including smallflower umbrella sedge ( Cyperus difformis ) (Derakhshan & Gherekhloo ), synedrella ( Synedrella nodiflora ) (Chauhan & Johnson ) and giant sensitive plant ( Mimosa invisa ) (Chauhan & Johnson ). Our findings suggest that, under field conditions, spreading of C. viscosa would be higher in fields in which zero or minimum‐tillage practices are performed.…”

Section: Resultsmentioning

confidence: 90%

Asian spiderflower (Cleome viscosa) germination ecology in southern Iran

Elahifard¹,

Derakhshan²

2018

Weed Biology and Management

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Cleome viscosa is one of the most important weeds of warm-season crops in southern Iran. Laboratory experiments were conducted to assess the impact of environmental factors on seed germination of C. viscosa. Freshly harvested seeds exhibited dormancy that was relieved (>90%) after immersion for 20 min in concentrated sulfuric acid. Regardless of the temperature regime, the final percentage of germination in light/dark (69.3%) was significantly higher than in complete darkness (58.3%). The optimum temperature for germination was 35/25 C in both light and dark. No germination was observed at constant temperatures of either 15 or 45 C. The thermal thresholds for seed germination, the base (T b ) and the mean ceiling germination temperatures (T c(50) ) were estimated to be 18.8 and 39.9 C, respectively. A base water potential (Ψ b(50) ) of −0.96 MPa was identified for C. viscosa seeds. The response threshold of C. viscosa to reduce 50% of maximum germination for salinity was estimated to be 255 mM. Seeds that were placed on the soil surface had the highest percentage of seedling emergence (77.3%), and no seedlings emerged from seeds placed at a depth of 6 cm. The findings of this study could help to improve the integrated weed management strategies for this species.

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“…Sigmoidal curves, also known as growth models, have wide application in agricultural research (MENDES et al, 2008;TERRA et al, 2010;DERAKHSHAN & GHEREKHLOO, 2013) and can be evaluated by means of nonlinear models, I Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Universidade de São Paulo (USP), Piracicaba, SP, Brasil. II Universidade Federal de Lavras (UFLA), Lavras, MG, Brasil.…”

Section: Introductionmentioning

confidence: 99%