alcohol dehydrogenase enzyme enhanced under various concentrations of active
chlorine [115]. As discussed above, seeds with parchments are used for sowing on
commercial purpose which hinders the normal germination process by providing the
tight barrier. But this parchment also proved to enhance the viability of stored seeds
as compared to hulled seeds irrespective the method of drying. Fifty percent hulled
seeds lost their viability in the first 3 months of storage and in 1 year all the hulled
seed lost their viability, whereas more than half seeds with parchment were still alive
[116–118]. But the dark side of this is that parchment and other seed germination
substrates may be the harbor of disease causing microbes and setting up these
seedlings in field, opening up the plant for additional microbial load from surroundings. The pruning activities, manual or mechanical harvesting of fruits, wet or dry
processing methods, etc., can vector these microbes not only from infected plants to
healthy plants but also will make the healthy seeds infected [119]. The detailed and
comprehensive reviews are available on the coffee microbiome, coffee microbial or
fungal diversity, diseases, and vectors [120, 121].
As the living genetic resource, the germplasm is used in the production of
improved coffee cultivars in terms of yield, yield stability, cup quality, and resistance
against insect pest and diseases so we would also like to discuss the cryopreservation
of coffee seeds. The work on the cryopreservation of germplasm of coffee is carried
out since 1990s to avoid the issues like genetic erosion due to poor adaptabilities to
new environments, labor cost, and large required space, to preserve the genetic
resources of coffee. Cryopreservation is also a suitable technique to preserve the
whole nonorthodox seed, and certain amount of work has also been carried out study
the intermediate whole seeds of coffee (e.g., C. arabica) which are partially desiccation tolerant. Seeds are normally predried to a certain level of moisture before the
cryopreservation. This may include shade or artificial drying. Abreu et al. [112]
found that shade-dried seeds with 20% moisture contents can maintain the quality
for 12 months. The precooling rate, drying rate, rewarming rate, initial seed lot
quality, seed moisture contents, and relative humidity for drying are critical research
factors addressed for the good viability and higher germination of desiccation
tolerant seeds [122–124]. The gradual precooling of seeds down to À50
C before
immersion into liquid nitrogen showed higher rate of seed viability and germination
than rapid cooling [122] while drying the seed with the 81% relative humidity which
was found to be optimum for cryopreservation [122] contrary to previous findings of
78% of the same author [123]. But the reason behind the advantageous gradual
precooling than rapid cooling is still a research topic to be resolved specifically in
coffee seeds. As coffee seeds also contained polyunsaturated fatty acids (PUFAs) in
fractional quantity, might be the cracking of lipid glasses, formed due to transition
phase of materials; in the membrane lead to the lower the viability in rapid cooling.
The simple and inexpensive procedure for the precooling was outlined by placing
seeds in the folding of ice in simple dry ice bath where the precooling rate is 10
C/
min which is also thought to be optimum. The other prejudicial factor is rewarming
or thawing rate which is no longer considered detrimental as coffee seeds are dried to
a moisture extent 17% or 20% that is equal to unfrozen water content in seeds before
the immersion in liquid nitrogen [123]. The aberrant findings of Vasquez et al. [124]
27 “Coffee Bean-Related” Agroecological Factors Affecting the Coffee
663
chlorine [115]. As discussed above, seeds with parchments are used for sowing on
commercial purpose which hinders the normal germination process by providing the
tight barrier. But this parchment also proved to enhance the viability of stored seeds
as compared to hulled seeds irrespective the method of drying. Fifty percent hulled
seeds lost their viability in the first 3 months of storage and in 1 year all the hulled
seed lost their viability, whereas more than half seeds with parchment were still alive
[116–118]. But the dark side of this is that parchment and other seed germination
substrates may be the harbor of disease causing microbes and setting up these
seedlings in field, opening up the plant for additional microbial load from surroundings. The pruning activities, manual or mechanical harvesting of fruits, wet or dry
processing methods, etc., can vector these microbes not only from infected plants to
healthy plants but also will make the healthy seeds infected [119]. The detailed and
comprehensive reviews are available on the coffee microbiome, coffee microbial or
fungal diversity, diseases, and vectors [120, 121].
As the living genetic resource, the germplasm is used in the production of
improved coffee cultivars in terms of yield, yield stability, cup quality, and resistance
against insect pest and diseases so we would also like to discuss the cryopreservation
of coffee seeds. The work on the cryopreservation of germplasm of coffee is carried
out since 1990s to avoid the issues like genetic erosion due to poor adaptabilities to
new environments, labor cost, and large required space, to preserve the genetic
resources of coffee. Cryopreservation is also a suitable technique to preserve the
whole nonorthodox seed, and certain amount of work has also been carried out study
the intermediate whole seeds of coffee (e.g., C. arabica) which are partially desiccation tolerant. Seeds are normally predried to a certain level of moisture before the
cryopreservation. This may include shade or artificial drying. Abreu et al. [112]
found that shade-dried seeds with 20% moisture contents can maintain the quality
for 12 months. The precooling rate, drying rate, rewarming rate, initial seed lot
quality, seed moisture contents, and relative humidity for drying are critical research
factors addressed for the good viability and higher germination of desiccation
tolerant seeds [122–124]. The gradual precooling of seeds down to À50
C before
immersion into liquid nitrogen showed higher rate of seed viability and germination
than rapid cooling [122] while drying the seed with the 81% relative humidity which
was found to be optimum for cryopreservation [122] contrary to previous findings of
78% of the same author [123]. But the reason behind the advantageous gradual
precooling than rapid cooling is still a research topic to be resolved specifically in
coffee seeds. As coffee seeds also contained polyunsaturated fatty acids (PUFAs) in
fractional quantity, might be the cracking of lipid glasses, formed due to transition
phase of materials; in the membrane lead to the lower the viability in rapid cooling.
The simple and inexpensive procedure for the precooling was outlined by placing
seeds in the folding of ice in simple dry ice bath where the precooling rate is 10
C/
min which is also thought to be optimum. The other prejudicial factor is rewarming
or thawing rate which is no longer considered detrimental as coffee seeds are dried to
a moisture extent 17% or 20% that is equal to unfrozen water content in seeds before
the immersion in liquid nitrogen [123]. The aberrant findings of Vasquez et al. [124]
27 “Coffee Bean-Related” Agroecological Factors Affecting the Coffee
663