SEED HEALTH OF COMMON BEAN STORED AT CONSTANT MOISTURE AND TEMPERATURE

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SEED HEALTH OF COMMON BEAN STORED AT

CONSTANT MOISTURE AND TEMPERATURE

Fabiana Gonçalves Francisco1_;_{Roberto Usberti}2_*

1

UNICAMP/FEAGRI - Programa de Pós-Graduação em Engenharia Agrícola - C.P. 6011, 13083-875, Campinas, SP - Brasil.

2

Coordenadoria de Defesa Agropecuária, SAA/SP. C. P. 960, 13073-001- Campinas, SP - Brasil. *Corresponding author <usberti@cati.sp.gov.br>

ABSTRACT: Fungal incidence in stored common bean (Phaseolus vulgaris L.) is the main concern in

order to preserve seed health and viability. The main aim of this study was to analyse these quality parameters in hermetically stored seeds at 10.2, 13.1, 16.2, 18.5% moisture content (MC) and 25, 30, 35, 40°C, through seed germination and health tests. Water activity recorded at 10.2 and 18.5% MC were 0.448 and 0.700, respectively. Low seed moisture content reduced Alternaria spp. incidence at

25-30°C. Highest incidence of Fusarium spp. (7.5%) occurred at 16.2% MC and 35-40°C. Highest incidences

of Rhizoctonia spp. (8-10%) were recorded at 16.2-18.5% MC and 30-40°C. Penicillium spp. and

Aspergillus spp. were predominant throughout the experiment and the highest incidences (80-100%;

20-30%, respectively) were scored at 18.5% MC and 30-35°C and 13.1-18.5% MC at 35°C, respectively. The higher the seed MC the higher the fungi incidence while lower seed MC decreased the incidences by 25%. Storage conditions below 30°C and 13.0% MC appear suitable to preserve common bean seed in relation to viability and health, up to a 8-month period.

Key words: seed healthiness, hermetic storage, fungal incidences

SANIDADE DE SEMENTES DE FEIJÃO ARMAZENADAS A

UMIDADE E TEMPERATURA CONSTANTES

RESUMO: A incidência de fungos em sementes de feijão (Phaseolus vulgaris L.) é a preocupação

principal de cientistas e tecnologistas de sementes visando preservar a sua sanidade e viabilidade. O objetivo deste estudo foi analisar esses parâmetros de qualidade em sementes hermeticamente armazenadas com graus de umidade de 10,2, 13,1, 16,2 e 18,5% a 25, 30, 35, 40°C, através de testes de germinação e de sanidade. Os valores de atividade de água obtidos para graus de umidade de 10,2 e 18,5% foram de 0,448 e 0,700. Baixos graus de umidade reduziram a incidência de Alternaria spp. a 25-30°C. A maior incidência

de Fusarium spp. (7,5%) ocorreu com grau de umidade de 16,2% a 35-40°C. As maiores incidências de

Rhizoctonia spp. (8-10%) foram registradas para graus de umidade de 16,2 e 18,5% a 30-40°C. Os fungos

Penicillium spp. e Aspergillus spp. foram predominantes durante todo o experimento, sendo que as

maiores incidências (80-100%; 20-30%) foram registradas para 18,5% de umidade a 30-35°C e 13,1-18,5% de umidade a 35°C, respectivamente. Quanto maior o grau de umidade da semente maior foi a incidência de fungos, enquanto que os valores mais baixos de umidade reduziram essas incidências a 25%. Temperaturas de armazenamento abaixo de 30°C e graus de umidades inferiores a 13,0% parecem ser as condições adequadas para preservar a viabilidade e a sanidade de sementes de feijão por até 8 meses. Palavras-chave: patologia de sementes, armazenamento hermético, incidência de fungos

INTRODUCTION

Brazil is one of the largest common bean pro-ducers in the world, therefore requiring high technol-ogy for the maintenance of seed quality parameters as to physical purity, germination and health percentages. Several factors may affect common bean seed servation, mainly including seed health, moisture con-tent (MC), temperature (T), relative humidity (RH) and the action of fungi and insects. High T and MC ac-celerate degenerative processes in biological systems,

causing gradual, irreversible and accumulative losses in vigour and viability (Delouche & Baskin, 1973). Seeds present a lower respiration rate during storage than external and internal fungi (Lazzari, 1993).

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Sci. Agric. (Piracicaba, Braz.), v.65, n.6, p.613-619, November/December 2008

emphasised seed health in open-stored common bean, not taking into account controlled environments.

Field fungi activity is delayed during storage

at low seed MC since they require ≥ 90% air RH for

growth (Lazzari, 1993). Fast development and high ag-gressiveness of these pathogens could kill the seed af-ter sowing due to the action of powerful enzymes and toxins. On the other hand, storage fungi usually de-velop in seeds in equilibrium at 65-90% air RH (around 12-13% MC) (Loewer et al., 1994). A decrease in field fungi and an increase in storage fungi populations oc-cur after harvest, in an ecological succession. The main objective of this research was to analyse seed germi-nation and fungi incidences in common bean under controlled storage conditions to define an optimum MC, storage period and T required to maintain high seed health and viability.

MATERIAL AND METHODS

Seven kg of common bean seeds cv. IAC-Ca-rioca ETE, were harvested in the 1998-99 season, in Campinas, São Paulo State, Brazil. Seed MC was ad-justed at 25°C to 10.2, 13.1, 16.2 and 18.5% MC, from an initial value of 15.1%, either by rehydration over water in a closed plastic box or by dehydration over silica gel, aiming to avoid possible damage to the seeds caused by fast dehydration / rehydration. Seeds were sealed in laminated aluminium-foil packets (polyester structure / aluminium / low-density polyethylene, with a total thickness of 120 mm) and stored in incubators maintained at 25, 30, 35 and 40°C (± 0.5°C).

Seed MC (fresh weight basis) was determined in three 5 g ground seed samples at 130-133°C for 2

h (ISTA, 2004). Water activity (A_w) was determined

using three seed samples for each MC in a hygrom-eter using the dew point technique, at 25°C ± 0.3 (±

0.01A_w). Germination tests were performed at 25°C

using 4 × 50 seed replicates for each MC /

tempera-ture / sampling date combination, placed in rolled pa-per towels moistened with deionised water, with ini-tial and final seedling counts recorded at the 5th and 9th days, respectively (ISTA, 2004).

Fungi incidences were determined by the

blot-ter test (Neergaard, 1977), using 200 seeds (20 × 10

replicates) for each MC / temperature / sampling date combination, incubated at 20°C during seven days un-der 12-h alternating cycles of NUV-light (320-400 nm) and darkness, followed by evaluation under a stereo-scopic microscope. Seeds were placed in plastic Petri dishes (9 cm diameter), with three filter papers moist-ened with sterilised water and previously decontami-nated in a 1% sodium hypochlorite solution for 5 min-utes (Berjark, 1984; Usberti & Amaral, 1999). Seed fungi incidences were estimated through observations of their structures (Barnett & Hunter, 1972).

Sampling intervals for seed health tests were quite variable due to the different levels of deteriora-tion in reladeteriora-tion to MC and storage T (Table 1). Pre-liminary results revealed no significant differences among initial and sampling time MCs. Fungi incidences for each combination among storage period, T and MC

were compared using Fisher’s LSD test (p < 0.05).

Prior to statistical analyses, germination percentages and fungi incidences were transformed into arcsine

√%/100 and √(x+1), respectively.

RESULTS AND DISCUSSION

Water activity

A_w is the quotient of seed vapour pressure over

pure water vapour pressure at the same temperature and is an important parameter in storage studies since it is closely related to rate and intensity of common

bean seed deterioration (Sartori, 1996). The A_wvalues

recorded on each seed MC (45-70% RH) were 0.448,

C M % 2 . 0

1 13.1%MC 16.2% MC 18.5%MC

C ° 5

2 30°C 35°C 40°C 25°C 30°C 35°C 40°C 25°C 30°C 35°C 40°C 25°C 30°C 35°C 40°C

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

9 8

1 189 118 118 150 150 189 109 130 15 4 3 24 15 4 2

2 4

2 242 200 200 242 200 214 116 200 24 7 7 104 23 7 4

7 0

2 205 242 123 214 60 11 11 109 49 11 7

0 1

2 210 130 259 100 23 18 116 60 21 10

4 1

2 214 132 109 56 22 123 63 29 18

0 3

2 216 137 130 60 25 130 70 39 22

0 4

1 63 29 140 43 29

2 3

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0.571, 0.674 and 0.700 for 10.2, 13.1, 16.2 and 18.5% MC, respectively.

Statistical analyses

Statistical analyses of fungi incidences on mon bean seeds are presented in Table 2, for each

com-bination of storage period, T and MC. No statistical interaction were recorded among fungi incidences,

storage T and seed MC. Penicillium spp. and

Aspergil-lus spp. revealed the highest incidences among fungi

throughout the experiment (Figures 1 and 2). Regres-sion lines of fungi incidences were observed in shorter

Figure 1 - Regression lines of storage fungi (Aspergillus spp. and Penicillium spp.) incidences (√(x+1)) in common bean seeds stored at 25, 30, 35, 40ºC and 10.2, 13.1, 16.2, 18.5% moisture content (MC).

Aspergillus

spp.

Penicillium

spp.

y = 0.003x + 1 R2_{= 1}

y = 0.0073x + 0.8931R2_{= 0.73}

y = 0.0032x + 1.2376 R2_{= 0.33}

y = 0.0179x + 1.2316 R2_{= 0.41}

0.0 1.0 2.0 3.0 4.0 5.0 6.0

0 50 100 150 200 250 300

Fungu

s i

nc

idence

(

√

(x+1))

10.2% MC 13.1% MC 16.2% MC 18.5% MC

18.5% MC

16.2% MC

13.1% MC

10.2% MC

30ºC

y = 0.002x + 1.0567 R2_{= 0.79}

y = 0.0065x + 1.0172 R2

= 0.47

y = 0.0519x + 1.0102 R2_{= 0.85}

y = -0.0122x + 1.8805 R2

= 0.02

0.0 1.0 2.0 3.0 4.0 5.0 6.0

0 50 100 150 200 250 300

Storage period (days)

Fun

gus in

ciden

ce

(

√

(x+

1)) 10.2% MC

13.1% MC 16.2% MC 18.5% MC

18.5% MC 16.2% MC

13.1% MC

10.2%

40ºC y = 0.0042x + 2.2183 R2_{= 0.08}

y = 0.0093x + 1.9107 R2_{= 0.16}

y = -0.0569x + 4.0805 R2_{= 0.11}

y = -0.1465x + 6.6408 R2_{= 0.11}

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

0 50 100 150 200 250 300

10.2% MC 13.1% MC 16.2% MC 18.5% MC

10.2% MC 13.1% MC

16.2% MC 18.5% MC

40ºC

y = 0.0018x + 1.4588 R2_{= 0.60}

y = -0.0014x + 1.702 R2_{= 0.86}

y = 0.0131x + 1.4257 R2_{= 0.80}

y = -0.0175x + 7.1749 R2_{= 0.20}

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

0 50 100 150 200 250 300

10.2% MC 13.1% MC 16.2% MC 18.5% MC

25ºC

y = 0.0077x + 1 R2_{= 1}

y = 0.0122x + 0.8828 R2_{= 0.66}

y = 0.0332x + 1.3079 R2_{= 0.63}

y = 0.0879x + 1.03 R2_{= 0.71}

0.0 1.0 2.0 3.0 4.0 5.0 6.0

0 50 100 150 200 250 300

F

undus i

nci

dence (

√

(x+1)

) 10.2% MC

13.1% MC 16.2% MC 18.5% MC 18.5% MC

16.2% MC 13.1% MC

10.2% MC

35ºC

y = 0.0009x + 1 R2_{= 1}

y = 0.0011x + 1.0684 R2_{= 0.43}

y = 0.0033x + 1.3859 R2_{= 0.23}

y = 0.0107x + 1.1021 R2_{= 0.43}

0.0 1.0 2.0 3.0 4.0 5.0 6.0

0 50 100 150 200 250 300

Fungu

s i

nc

idenc

e

(√

(x+

1)) 10.2% MC_{13.1% MC} 16.2% MC

18.5% MC 16.2% MC

18.5% MC _{13.1% MC}

10.2% MC

25ºC

y = 0.001x + 1.3814 R2_{= 0.45}

y = 0.007x + 1.5234 R2_{= 0.69}

y = 0.0115x + 2.4361 R2_{= 0.10}

y = 0.0255x + 5.1268 R2_{= 0.12}

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

0 50 100 150 200 250 300

10.2% MC 13.1% MC 16.2% MC 18.5% MC

30ºC

10.2% MC 13.1% MC 16.2% MC

18.5% MC

y = 0.001x + 1.3814 R2

= 0.45

y = 0.007x + 1.5234 R2_{= 0.69}

y = 0.0115x + 2.4361 R2_{= 0.10}

y = 0.0255x + 5.1268 R2_{= 0.12}

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

0 50 100 150 200 250 300

10.2% MC 13.1% MC 16.2% MC 18.5% MC

35ºC

10.2% MC 13.1% MC 16.2% MC

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616

storage periods according to increases on seed MC and storage T.

The determination coefficients estimated for storage fungi incidences (Figure 1), ranging from 0.08 to 1, revealed a decreasing tendency, according to in-creases on MC and storage T. However, the values re-corded for field fungi incidences (Figure 2) were quite variable, ranging from zero to 1, without showing a specific tendency.

Storage fungi incidences

Penicillium spp. and Aspergillus spp. are the

main storage fungi in common bean and usually in-vade the seeds during and after maturation, causing damage as soon as they find appropriate conditions.

The primary coloniser is Aspergillus spp., which

sub-sequently allows the developmentof Penicillium spp.

(Faiad et al., 1996). Penicillium spp. and Aspergillus

spp. incidences scored in common bean seeds stored at 25, 30, 35, 40°C and 10.2, 13.1, 16.2, 18.5% MC are presented in Figure 1.

Aspergillus spp. - Fungal incidences higher

than 20% were recorded at different MC / tempera-ture combinations, mainly in early storage periods and 16.2-18.5% MC, except at 10.2-13.1% MC / 35-40°C, when these values were scored until 200-230-day stor-age periods. Regardless of T, 10.2-13.1% seed MC reduced fungal invasion until the 214-day storage when values around 6-8% were registered at 35°C; however

Figure 2 - Regression lines of field fungi (Alternaria spp., Fusarium spp. and Rhizoctonia spp.) incidences (√(X+1)) in common bean seeds stored at 25, 30, 35, 40ºC and 10.2, 13.1, 16.2, 18.5% moisture content (MC).

y = 2.4495 R2 = #N/D y = 0.0009x + 1.7919 R2

= 0.50 y = -0.0055x + 2.3407 R2

= 0.22 y = -0.0089x + 2.3724 R2

= 0.02 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0 50 100 150 200 250

Fungus incidence ( Ö (x+1)) 10.2% MC 13.1% MC 16.2% MC 18.5% MC 10.2% MC 13.1% MC 16.2% MC 18.5% MC

25ºC y = 1 R

2_{= #N/D} y = -0.0005x + 1.4068 R2

= 0.01 y = -0.0042x + 1.3977 R2

= 0.22 y = -0.0236x + 1.4258 R2

= 0.57 0.0 0.5 1.0 1.5 2.0 2.5 3.0

0 50 100 150 200 250

10.2% MC 13.1% MC 16.2% MC 18.5% MC 10.2% MC 13.1% MC 16.2% MC 18.5% MC 25ºC

y = -0.0072x + 1.8209 R2 = 0.93 y = -0.0019x + 1.2247 R2

= 1 y = 0.0056x + 0.8989 R2

= 0.92 y = -0.0226x + 1.4722 R2

= 0.06 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0 50 100 150 200 250

10.2% MC 13.1% MC 16.2% MC 18.5% MC 25ºC 10.2% MC 13.1% MC 16.2% MC 18.5% MC

y = -0.0011x + 2.4233 R2 = 0.07 y = -0.0055x + 1.8708 R2

= 1 y = -0.0243x + 2.847 R2

= 0.55 y = 0.008x + 2.2275 R2

= 0.16 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0 50 100 150 200 250

Fungus incidence ( Ö (x+a)) 10.2% MC 13.1% MC 16.2% MC 18.5% MC 13.1% MC 16.2% MC 18.5% MC 30ºC 10.2% MC

y = 1 R2 = #N/D y = -0.0016x + 1.5749 R2

= 0.13 y = -0.008x + 1.7587 R2

= 0.42 y = 0.0003x + 1.3443 R2

= 0.0001 0.0 0.5 1.0 1.5 2.0 2.5 3.0

0 50 100 150 200 250

y = -0.0011x + 1.716 R2 = 0.18 y = -0.0018x + 1.2233 R2

= 0.99 y = -0.005x + 1.7623 R2

= 0.06 y = -0.0054x + 1.7753 R2

= 0.18 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0 50 100 150 200 250

10.2% MC 13.1% MC 16.2% MC 18.5% MC 10.2% MC 13.1% MC 16.2% MC 18.5% MC 30ºC

y = -0.0065x + 2.4495 R2 = 1 y = -0.0012x + 1.9024 R2

= 0.15 y = -0.0201x + 2.5446 R2

= 0.51 y = -0.0242x + 2.6951 R2_{= 0.34}

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0 50 100 150 200 250

Fungus incidence ( Ö (x+1)) 10.2% MC 13.1% MC 16.2% MC 18.5% MC 35ºC 18.5% 16.2% MC 13.1% MC 10.2% MC

y = 1 R2 = #N/D y = -0.0062x + 1.7321 R2

= 1 y = -0.0068x + 1.9393 R2

= 0.16 y = -0.0194x + 1.5819 R2

= 0.39 0.0 0.5 1.0 1.5 2.0 2.5 3.0

0 50 100 150 200 250

10.2% MC 13.1% MC 16.2% MC 18.5% MC

35ºC

10.2% MC 13.1% MC 16.2% MC 18.5% MC

y = -0.007x + 1.7321 R2 = 1 y = -0.0019x + 1.2231 R2

= 0.99 y = -0.0264x + 2.2989 R2

= 0.11 y = -0.021x + 1.813 R2

= 0.13 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0 50 100 150 200 250

y = -0.0061x + 2.4495 R2 = 1 y = -0.003x + 1.8707 R2

= 1 y = -0.0154x + 2.7415 R2

= 0.16 y = 0.007x + 2.158 R2

= 0.10 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0 50 100 150 200 250

Fungus incidence ( Ö (x+1)) 10.2% MC 13.1% MC 16.2% MC 18.5% MC 40ºC 18.5% MC 16.2% MC 13.1% MC 10.2% MC

y = 0.0015x + 0.95 R2 = 0.18 y = -0.0065x + 1.7306 R2

= 1 y = -0.0157x + 2.0561 R2

= 0.12 y = -0.0216x + 1.764 R2

= 0.12 0.0 0.5 1.0 1.5 2.0 2.5 3.0

0 50 100 150 200 250

y = -0.0037x + 1.6464 R2 = 0.84 y = -0.0019x + 1.2231 R2

= 0.99 y = -0.0114x + 2.2161 R2

= 0.03 y = -0.0122x + 1.9405 R2

= 0.02 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0 50 100 150 200 250

10.2% MC 13.1% MC 16.2% MC 18.5% MC 40ºC 10.2% MC 13.1% MC 16.2% MC

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they increased by about 20% at 40°C. Highest and ear-liest values were recorded at 16.2-18.5% MC / 35-40°C, respectively.

The presence of Aspergillus spp. in bean

seeds was reported by Christensen (1972); Faiad et al. (1996) and Sinha et al. (1999); however, its oc-currence was always associated with the presence of

Penicillium spp. (Bolkan et al., 1976; Dhingra &

Sinclair, 1978). A high incidence of Aspergillus spp.

(77%) was detected in bean seeds during 24-month open storage conditions at 85-95% RH (Hernandez et al., 1994).

Penicillium spp. - Penicillium spp. had the

highest incidences in common bean seeds, mainly at 18.5% MC and 30-40°C (80-100%) while still higher values (around 60%) were recorded at 25°C and 16.2-18.5% MC. The higher the storage T, the higher the fungus invasion during early storage periods. Lowest seed MC (10.2-13.1%) reduced fungus incidences; however, at 30-35°C, the values reached 10%, while at 40°C some values were higher than 20%. The best T range for fungus invasion was 30-35°C and MC higher than 16%.

Highest incidences of Penicillium spp. were

observed at 18.5% MC at all T, while Aspergillus spp.

contamination was only pronounced at 35°C; so, the

higher the seed MC, the higher the fungal incidences at early storage periods. Additional high T effects on

fungi incidences could also be noted. Penicillium spp.

and Aspergillus spp. presented the highest incidences

in common bean seeds during hermetic storage. These

results agree with Terveit (1945); Wilcox et al.(1974);

Bolkan et al. (1976); Dhingra & Sinclair (1978) and

Hernandez et al. (1994).

Field fungi incidences - The most common

field fungi detected in fresh bean seeds were

Alterna-ria spp. and Fusarium spp. (Figure 2), which require

seed MC in equilibrium to 90% RH for growing and cause great impacts in crop yields (Abawi et al., 1977; Pieczarka & Abawi, 1978; Sinha et al., 1999). Field fungi incidences remained below 12% throughout the experi-ment and lowest MC / T combinations (10.2-13.1% and 25-30°C) reduced the values below 6% (Figure 2).

High-est incidences of Alternaria spp. (8-12%) were observed

at 16.2-18.5% MC, however low MC were effective in restraining them. The higher T, the greater the

fun-gus incidence. On the other hand, Fusarium spp.

oc-curred mainly at 16.2% MC and 35-40°C and remained

below than 3.5% at 25-30°C. Rhizoctonia spp.highest

incidence (8-10%) was detected at 18.5% MC and 30-40°C, however at 25°C the fungus occurrence was re-duced. Field and storage fungi incidences were clearly reduced for the lowest MC (10.2%, 13.1%) at

25-30°C, with values remaining below 5 and 10%, respec-tively (Figures 1 and 2).

Seed germination

Increases in MC reduced seed viability and this effect was more pronounced for highest seed MC (16.2, 18.5%), unrelated to storage T (Figure 3). The

Figure 3 - Regression lines of standard germination (arcsine

√(%/100)) of common bean seeds stored at 25, 30, 35, 40ºC and 10.2, 13.1, 16.2, 18.5% moisture content.

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0 50 100 150 200 250 300

G

ermin

at

io

n (a

rc

se

n √

(%

/100)

)

25ºC 30ºC

35ºC 40ºC

18.5% MC

25ºC 30ºC 35ºC 40ºC

y = -0.006x + 1.977 R² = 0.68

y = -0.0329x + 1.0999 R² = 0.67 y = -0.0092x + 1.0007 R² = 0.58 y = -0.0197x + 1.0944 R² = 0.78

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0 50 100 150 200 250 300

Ge

rm

ination (

ar

cs

en

√

(%

/1

00

))

25ºC

30ºC 35ºC

40ºC

16.2% MC

25ºC 30ºC 35ºC 40ºC

y = -0.003x + 1.1127 R² = 0.68

y = -0.0295x + 1.1883 R² = 0.73 y = -0.0057x + 1.0402 R² = 0.7 y = -0.01x + 1.0467 R² = 0.50

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0 50 100 150 200 250 300

Ge

rmina

tion

(

ar

cs

en

√

(%

/100

) 10.2% MC

25ºC

30ºC 35ºC

40ºC

25ºC 30ºC 35ºC 40ºC

y = -0.0011x + 1.0634 R² = 0.57

y = -0.0038x + 1.2 R² = 0.75 y = -0.0025x + 0.9919 R² = 0.75 y = -0.0027x + 1.0761 R² = 0.49

Storage period

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

0 50 100 150 200 250 300

Ge

rm

ination (

ar

cs

en

√

(%

/1

00

)

25ºC 30ºC 35ºC 40ºC

13.1% MC

25ºC 30ºC 35ºC 40ºC

y = -0.0024x + 1.0429 R² = 0.74

y = -0.0055x + 1.1637 R² = 0.73 y = -0.0027x + 1.0837 R² = 0.94 y = -0.0036x + 1.2775 R² = 0.71

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determination coefficients calculated for germination percentages were quite high, ranging from 0.49 to 0.94, without showing a specific tendency according to MC and storage T.

Some germination percentage reductions ob-served throughout the storage period might be

influ-enced by previous high incidences of Penicillium spp.

(60.5% at 130-day; 36.5% at 132-day) (Figure 1).

Moreover, some early high incidences of Aspergillus

spp. at 40 to 60-day storage could play an additional role in the deterioration process.

Similar results were reported by Chisholm & Coates (1997), evaluating germination percentages and fungi incidences in three leguminous seeds during stor-age with subsequent germination reduction and increase in fungi incidences mainly at 28°C. Stored beans (10.3-14.2% MC at 30°C) with high initial seed germination percentage and MC around 11.5% might maintain vi-ability for eight months (Aguirre & Peske, 1991). Sanhewe & Ellis (1996) have also reported that bean seed quality was higher at cold temperatures during development and maturation.

CONCLUSIONS

Storage conditions with moisture content and temperature lower than 13.1% and 30°C, respectively, appear to be adequate for maintenance of seed viabil-ity and healthiness up to 8-months storage. Such stor-age conditions, which might be easily reached by seed sun drying and open storage, suggest a closing remark as to potential benefits and offer seed producers with a strategy for maintaining seed viability.

ACKNOWLEDGEMENTS

To CNPq for the grant of Fabiana Gonçalves Francisco as well as to the Packaging Technology Cen-ter, Institute of Food Technology, Campinas, Brazil for providing the facilities for packaging the seeds and de-tecting equilibrium relative humidities.

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