Effect of different levels of Sigatoka disease severity on banana pulp colour and early ripening

Figures & data

Table 1. Initial plant classification level by Severity Index.

	Replicate 1		Replicate 2		Replicate 3
Level	SI^a	N^b	SI^a	N^b	SI^a	N^b
1	3.3	10	3.7	10	3.8	10
2	9.9	10	10.9	10	11.0	10
3	30.4	10	31.0	10	21.5	10
4	41.4	10	40.9	10	37.4	10

^aSI at flowering stage, with the method developed by Stover (1971) and modified by Gauhl et al. (1993).

^bNumber of plants.

Table 2. Percentage of ripe fruits in the field before harvest time and green life (GL).

Level	% of ripe fruits^a	GL^b
1	0.00 ± 0.00 (c)	47.91 ± 5.20 (a)
2	0.00 ± 0.00 (c)	31.96 ± 3.94 (b)
3	33.33 ± 0.58 (b)	16.69 ± 3.19 (c)
4	70.00 ± 1.00 (a)	9.68 ± 4.96 (c)
F	475.35	28.14
P	<0.0001	0.000

^aThe values represent the average ± standard deviation. They were calculated from the number of ripe fruits at harvest for each replicate.

^bNumber of days between harvest and the start of the natural ripening process, measured as described by Chillet et al. (2008) at 13 °C. To compare the percentage of ripe fruit by ANOVA, it was necessary to transform the data into arcsine (% Ripe Fruit). Fruits were harvested at 900 degree days of physiological age, as calculated by the mean temperature sum based on a 14 °C threshold. Disease level was established by SI.

Table 3. Pomological parameters (weight, diameter) of fruits harvested at 900 degrees days from plants differentially infested by Sigatoka disease.

Level	Weight (g)	Diameter (mm)
1	175.91 ± 7.57 (a)	34.80 ± 0.84 (ns)
2	161.78 ± 11.08 (b)	34.63 ± 0.56 (ns)
3	142.38 ± 11.57 (c)	33.15 ± 0.98 (ns)
4	138.98 ± 5.74 (c)	34.17 ± 0.29 (ns)
F	27.03	3.19
P	0.001	0.084

The values represent the average ± standard deviation; (a) and (b) are statistically different groups, (ns) means no significant difference. The disease level was established by SI.

Table 4. Pulp colour (L*, a*, b*) of fruits harvested at 900 degrees days from plants differentially infested by Sigatoka disease.

Level	L*	a*	b*
1	87.65 ± 1.11 (a)	−1.95 ± 0.39 (c)	31.26 ± 1.30 (c)
2	86.46 ± 0.73 (a)	−1.04 ± 0.48 (b)	34.64 ± 1.29 (b)
3	84.09 ± 1.80 (b)	0.50 ± 0.49 (a)	38.96 ± 0.71 (a)
4	83.98 ± 2.03 (b)	0.76 ± 0.50 (a)	39.13 ± 0.24 (a)
F	11.83	137.87	32.59
P	0.005	<0.0001	<0.0001

The values represent the average ± standard deviation; (a) and (b) are statistically different groups, (ns) means no significant difference. The disease level was established by SI intervals.

Fig. 1. Pulp colour (a*) depending on Severity Index (SI) value of fruits harvested at a constant physiological age (900 dd) according to the method described by Ganry and Chillet (2008). The SI is calculated from the method of Stover (1971).

Fig. 2. Green life (GL in days) depending on pulp colour (a*) of fruits harvested at a constant physiological age (900 dd) according to the method described by Ganry and Chillet (2008).

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