Page 92 - Ecuador's Banana Sector under Climate Change

ecuador’s banana sector under climate change: an economic and biophysical assessment to promote a sustainable and climate-compatible strategy
weather station (Figure 19). These daily patterns were then used in two calculations for BS - velocity of evolution and state of evolution. In the first case, the calculation is based on the relation on the speed of growth of the germination tube of conidia and ascospores linked to temperature. In the second case, disease development rate is calculated, based on the link with rainfall and humidity two weeks after.
The velocity of evolution (SDR) of BS is linked to temperature. The minimum temperature for the germination of BS, or Mycosphaerella fijiensis, is 12oC,
the optimal is 27oC and the maximum is 36oC (Porras and Pérez, 1997;
Pérez et al., 2006). In general, the germination of conidia is optimal between 25 and 30oC, following a quadratic response with an estimation of 26.5oC
as an optimal temperature for germination. Furthermore, almost 100 percent germination is presented after 24 hours (Jacome, Schuh and Stevenson, 1991; Jacome and Schuh, 1992). For ascospore germination, an optimal temperature of 25oC was estimated (Jacome, Schuh and Stevenson, 1991; Jacome and Schuh, 1992). In relation to relative humidity, ascospore and conidia respond differently. Ascospores germinate only with a higher relative humidity than
98 percent, while conidia germinates with a wider range of humidity (88-100 percent) (Jacome, Schuh and Stevenson, 1991). The impact of the changes in temperature due to climate change on BS was estimated by the weekly cumulative sum development rates of evolution, based on the development of the germination tube (Porras and Pérez, 1997). The daily sum of development rates of evolution of BS was calculated with a simple regression, based on maximum and minimum daily temperature, developed by Porras and Pérez (1997), with the following equation:
Figure 19
600 500 400 300 200 100
SDR= 7.18 * Tmax + 79.16 * Tmin
Valid for a range of temperatures between 10oC and 35oC.
Projected distributions compared with daily distribution from Pichilingue’s weather station*
Precipitation
Temp. Max
Temp. Min
Temp. Mean
35 600
30 500
25 400
35 30 25 20 15 10 5
20 15
300
10 200
5 100
0 0 AB
Jan Feb MarAprMayJun Jul AugSepOctNovDec 0 *: A: MarkSimTM produced distribution, B: Pichilinge weather station
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0 Jan FebMarAprMayJun Jul AugSepOctNovDec