Growth and Development of Purple Nutsedge Based on Days or Thermal Units

Planta Daninha

R.s.o. Lima¹  E.c.r. Machado¹  A.p.p. Silva¹  B.s. Marques¹  M.f. Gonçalves¹  S.j.p. Carvalho¹ 

关键词: Cyperus rotundus;    growing degree days;    phenology;    base temperature;    modeling;    Cyperus rotundus;    graus-dia;    fenologia;    temperatura basal;    modelagem;   

DOI  :  10.1590/0100-83582015000200001

来源: SciELO

【 摘 要 】

This work was carried out with the objective of elaborating mathematical models to predict growth and development of purple nutsedge (Cyperus rotundus) based on days or accumulated thermal units (growing degree days). Thus, two independent trials were developed, the first with a decreasing photoperiod (March to July) and the second with an increasing photoperiod (August to November). In each trial, ten assessments of plant growth and development were performed, quantifying total dry matter and the species phenology. After that, phenology was fit to first degree equations, considering individual trials or their grouping. In the same way, the total dry matter was fit to logistic-type models. In all regressions four temporal scales possibilities were assessed for the x axis: accumulated days or growing degree days (GDD) with base temperatures (Tb) of 10, 12 and 15 oC. For both photoperiod conditions, growth and development of purple nutsedge were adequately fit to prediction mathematical models based on accumulated thermal units, highlighting Tb = 12 oC. Considering GDD calculated with Tb = 12 oC, purple nutsedge phenology may be predicted by y = 0.113x, while species growth may be predicted by y = 37.678/(1+(x/509.353)-7.047).

【 授权许可】

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