5 research outputs found
Inhibitors of Non-for Profit Organisationsâ activities and survival in a crisis context
Purpose Tunisia has been living a decade of democratic transition since 2011. In this new context, the civil society has been fervently expressing claims for democracy and social justice through creating thousands of NPOs (23456 NPOs in 2020 against 9000 established in 30 years up to 2010). However, this shift seems to be misleading, as only 3000 NPOs are actually active, indicating that NPOs are struggling to sustain their activities and ensure their survival. The purpose of this study is to uncover the factors hindering NPOs activities and survival. Design/methodology/approach Semi-structured interviews were carried out using a purposive sample of 32 NPOs members in two main economic and touristic cities -Tunis and Sousse- selected using snow ball method. A considerable amount of qualitative data was produced (400 pages of text). This seems representative of Tunisian citizensâ inclination to protest in the new prevailing political and social context. The data collection benefited from the freedom of speech gained after the 2011 civilian uprising as interviewees were enthusiastic in voicing their opinions. Findings Two main categories of inhibitors were identified. First, endogenous inhibitors including (i) inhibitors under the control of the NPO (i.e. use of illegal and foreign sources of funding, limited financial resources, unavailability of NPOsâ members, short term planning, conflicts between managers, autocratic leadership, organisational support, activities diversification and organisational justice, leadership and communication skills, âNPO cultureâ, membersâ opportunistic behaviour and, generation gap) (ii) inhibitors related to NPOs inter-relationships: stiff competition, unfair and dishonest competition, lack of collaboration, trust and communication between NPOs. Second, exogenous inhibitors, i.e. perceived unethical practices and image transfer, economic crisis, foreign funding sources and the media. Research limitations/implications This study has some limitations mainly due to the sample size and characteristics of the selected interviewees. In addition, data was collected in only two regions (Tunis and Sousse). Therefore, the results lack generalisability. â Practical implications The findings highlight the critical impact of the inhibitors under the control of NPOs compared to those out of their control. NPOs in crisis context, could overcome these inhibitors by ensuring congruence between the NPOsâ mission, objectives and activities and designing suitable marketing strategies. Originality/value This study contributes to elucidate this complex circular system of exchange and its inhibitors in challenging and understudied context. It offers support to Bagozziâs (1974; 1975; 1994; 2011) calls for uncovering the factors constraining or facilitating exchanges that have an impact going beyond the relationship between three or more partners and the conditions that govern these exchanges. Moreover, and to the best of our knowledge, this is the first empirical attempt to support Bagozziâs (1994) conceptualisation. It also brings an update to NPOs' data and marketing strategy in a region near the crossroads of Middle Eastern, North African and Western influences. Keywords: Not For Profit Organisations (NPOs), endogenous and exogenous inhibitors, NPOsâ inter-relationship, circular exchange system
Effect of Thiourea on Yield and Quality of Potato (Solanum tuberosum L.)
A field experiment was carried out to study the effect of five concentrations (0, 250, 500, 750 and 1000 mM) of thiourea application on mother tubers on yield and quality attributes of harvested potato, variety Spunta in the region of Chott-Mariem in Tunisia. Treated tubers (Đš = 50 mm) were planted in field after breaking dormancy at a spacing of 80 cm x 30 cm according to completely randomized design (CRD) in three replications. Quality attributes of potato tubers especially fresh matter and dry matter of plant, total reducing sugars in leaves, tuber yield, number and diameter of tubers per plant and number of sprouts per tuber was measured. Soluble proteins and starch content in potato tubers were also quantified.In general we noted that application of thiourea showed significant influence on yield and on quality of tubers comparing to control. Maximum tuber yield per plant, maximum number of tubers per plant and maximum starch content was recorded with 250 mM of thiourea. Moreover, highest dry matter of potato plant was found also at this concentration. While increasing dose of thiourea thereafter it showed slight significant improvement and do not affect significantly the diameter of tubers comparing to control
PHYSIOLOGICAL MECHANISMS FOR POTATO DORMANCY RELEASE AND SPROUTING: A REVIEW
Potato ( Solanum tuberosum \ua0L.) tubers undergo a period of
dormancy, during which visible bud growth is inhibited. The length of
the dormancy is determined by environmental, physiological and hormonal
control mechanisms. Dormancy is the final stage of tuber life, which
serves to preserve tubers as organs of vegetative reproduction under
unfavourable growth conditions. Since the duration of potato tuber
dormancy and sprouting time bear significant economic importance, this
review considers the regulation of dormancy and sprouting of potato by
phytohormones and reactive oxygen species. Two phytohormones, ABA and
ethylene suppress tuber sprouting; however, the exact role of ethylene
remains to be elucidated. Cytokinins and gibberellins are required for
bud breaking and sprout growth, respectively. The auxin seems to play a
role in vascular development. Thus, tuber dormancy and sprouting can be
controlled in potato by manipulation of Reactive Oxygen Species (ROS),
especially H2O2\ua0metabolism via the inhibition of catalase (CAT)
activity.The possible mechanisms by which CAT inhibitors or
H2O2\ua0overcome dormancy and promote sprouting in the potato tuber
are discussed.La pomme de terre ( Solanum tuberosum \ua0L.) conna\ueet une
p\ue9riode de dormance durant laquelle la germination des bourgeons
visibles est inhib\ue9e. La dur\ue9e de dormance est
d\ue9termin\ue9e par des m\ue9canismes de contr\uf4le
environnemental, physiologique and hormonal. La dormance est le stade
final de la vie des tubercules servant \ue0 pr\ue9server les
tubercules comme organes de reproduction v\ue9g\ue9tative sous
condition de germination d\ue9favorables. Etant donn\ue9 que la
dur\ue9e de la dormance des tubercules de la pomme de terre et le
temps de rejet rev\ueatent une importance \ue9conomique
significative, cette revue consid\ue8re la r\ue9gulation de la
dormance et le rejet de la pomme de terre par des hormones et
d\u2019esp\ue8ces r\ue9actives d\u2019oxyg\ue8ne (ROS). Deux
phytohormones\ua0; ABA et \ue9thyl\ue8ne emp\ueachent le rejet
des tubercules\ua0; par ailleurs, le r\uf4le extractif de
l\u2019\ue9thyl\ue8ne reste \ue0 \ue9lucider. Les cytokinines
and les gibb\ue9rellines sont n\ue9cessaires dans
l\u2019\ue9limination des bourgeons et la croissance des rejets,
respectivement. L\u2019auxine semble jouer un r\uf4le dans le
d\ue9veloppement vasculaire. Ainsi, la dormance et les rejets des
tubercules peuvent \ueatre contr\uf4l\ue9s par manipulation
d\u2019esp\ue8ces r\ue9actives d\u2019oxyg\ue8ne (ROS),
sp\ue9cialement le m\ue9tabolisme du H2O2\ua0\ue0 travers
l\u2019inhibition de l\u2019activit\ue9 de la catalase (CAT). Les
m\ue9canismes possibles par lesquels les inhibiteurs du CAT ou
H2O2\ua0 surmontent la dormance et facilitent le rejet de la pomme de
terre sont discut\ue9s
EFFECT OF HYDROGEN PEROXIDE AND THIOUREA ON DORMANCY BREAKING OF MICROTUBERS AND FIELD-GROWN TUBERS OF POTATO
Potato ( Solanum tuberosum L.) microtubers or field-grown tubers have
a dormant apical bud (also called tuber dormancy). They do not readily
sprout even if environmental conditions are favorable, including
optimum temperature and humidity. The objective of this study was to
evaluate the involvement of hydrogen peroxide (by direct or indirect
application of thiourea, a catalase inhibitor) in dormancy release and
sprouting of potato microtubers and tubers was evaluated using two
complementary experiments. First, the kinetics of the sprouting
(percentage of sprouted microtubers with time) was examined on
microtubers planted in peat and cultivated in a glasshouse after
exogenous application of different concentrations of hydrogen peroxide
(20, 40 and 60 mM) and thiourea (250, 50 0 and 750 mM). Second, the
sprouting kinetics was examined on field-grown tubers during storage,
after application of hydrogen peroxide (20, 40, 60 and 80 mM) and
thiourea (250, 500, 750 and 1000 mM). Their sprouting capacity was also
evaluated. Then, kinetics of field emergence of treated and sprouted
tubers was examined after planting them in a field. Direct application
of hydrogen peroxide or application of catalase inhibition through
thiourea application on the release of dormancy promote sprouting on
potato microtubers and field-grown tubers. Results showed that hydrogen
peroxide (20 mM) caused rapid and synchronous sprouting of microtubers;
while higher concentrations (40 and 60 mM), caused asynchronous
sprouting. Thiourea at a concentration of 250 mM was the most effective
in reducing the dormancy period and increasing the number of sprouted
microtubers. In field experiment, sprouting was optimal when tubers
were treated with 60 mM of hydrogen peroxide; whereas at a lower
concentration, sprouting was less stimulated. In addition, tubers
treated with 250 mM thiourea had maximum sprouting and better sprouting
capacity. It is clear that both substances affect hormonal regulation
and antioxidant enzymes, leading to dormancy release in both:
microtubers and tubers.Les microtubercules de la pomme de terre ( Solanum tuberosum L.) ou
bien les tubercules cultivées en champs sont dotées
dâune dormance des tubercules. Elle ne poussent pas facilement,
mĂȘme si les conditions environnementales sont favorable, incluant
tempĂ©rature optimal et lâ humiditĂ©. Lâobjectif de
cette thiourea, une catalase inhibitrice) dans la libération de la
dormance et la germination des microtubercules de pomme de terre
était évalué utilisant deux essais complémentaires.
Dâabord, la cinĂ©tique de germination (pourcentage de
microtubercules germées avec le temps) était examinee sur des
microtubercules plantées sur susbtract tourbeux et cultivées
dans une serre aprÚs application exogÚne de différentes
concentrations du peroxide dâhydrogĂšne (20, 40 et 60 mM) et
thiourea (250, 50 0 et 750 mM). DeuxiÚmement, la cinétique de
germination était examinée pendant le stockage sur des
tubercules cultivées en champ aprÚs application du peroxide
dâhydrogĂšne (20, 40, 60 et 80 mM) et thiourea (250, 500, 750
et 1000 mM). Leur capacité de germination était
Ă©valuĂ©e. En suite, la cinĂ©tique dâĂ©mergence
au champs des tubercules traitées et germées était
examinée aprÚs les avoir plantées au champs.
Lâapplication directe du peroxide dâhydrogĂšne ou
application de la catalase inhibitrice Ă travers lâ
application du thiourea sur la liberation de la dormance promeut la
germination des microtbercules ainsi que les tubercules produites en
champs. Les résultats ont montré que le peroxide
dâhydrogĂšne (20 mM) ont cause un rapide et une germination
synchronisée des microtubercules; alors que les concentration plus
élevées (40 et 60 mM), ont cause une germination non
synchronisées. Thiourea avec une concentration de 250 mM
était le plus efficace en terme de réduction de la
pĂ©riode de dormance et lâaugmentation du nombre des
microtubercules germĂ©es. Dans lâessai en champs, la
germination Ă©tait optimal lorsque les tubercules Ă©taient
traitĂ©es avec 60 mM du peroxide dâ hydrogen; pendant
quâ Ă une basse concentration, la germination Ă©tait
moins stimulées. En plus, les tubercules treatées avec 250 mM
de thiourea avaient un maximum de germination et une meilleur
capacité de germination. Il est claire que toutes les deux
substances affectent la regulation hormonale et les enzymes
antioxidants, conduisant ainsi à la libétation de la dormance
dans les microtbercules et les tubercules
Effect of hydrogen peroxide and thiourea on fluorescence and tuberization of potato (Solanum tuberosum L.)
The aim of this study is to determine the effect of hydrogen peroxide and thiourea on potato crop (quantum yield (Fv/ Fm), chlorophyll content, tuber diameter, tuber number and total tuber yield). The concentrations of these two chemicals are hydrogen peroxide: 0, 20, 40, 60 and 80 mM, and thiourea : 0, 250, 500, 750 and 1000 mM. The experiment was conducted in the farm of Chott-Mariem Institute during three months using variety 'Spunta' and arranged in a completely randomized block with three replications. Results show that there is no significant difference in tuber diameter between treatments and among the same treatment. However, tuber yield is significantly increased by 20 % by thiourea (250 mM). Maximum total yield was obtained at this concentration (810 g/plant). In addition, application of thiourea (500 and 750 mM) results in a significantly higher number of tubers number (5.7 and 5.2 respectively). In contrast, treatment with hydrogen peroxide brings about similar tuber yields. Although, application of hydrogen peroxide at low concentration (20 mM), decreases chlorophyll content and stresses plants, application of thiourea increases chlorophyll content, and improve quantum yield especially when it is applied at 250 mM