Phenological Growth stages of saffron Plant (Crocus sativus L.) according to the BBCH Scale

Abstract

Phenological studies are important for understanding the influence of climate dynamics on vegetative growth, flowering and fruiting on plants and can be used in many scientific subjects, such as Agronomy, Botany and Plant Biology, but also Climatology as a result of the current global interest in climate change monitoring. The purpose of the detailed specific culture descriptions of the principal growth stages in plants is to provide an instrument for standardization of data recording. To date, there was no coding method to describe developmental stages on saffron plant (Crocus sativus L.). Because of the increasing world-wide interest on this crop, a novel growth development code based on the BBCH extended scale is proposed in this paper. Six principal growth stages were set up, starting from sprouting, cataphylls and flowers appearance, plant appearance and development, replacement corms development, plant senescence and corm dormancy. Each principal growth stage is subdivided into secondary growth stages. Descriptive keys with illustrations are included to make effective use of the system.

Full text

Spanish Journal of Agricultural Research
13(3), e09SC01, 7 pages (2015)
eISSN: 2171-9292
http://dx.doi.org/10.5424/sjar/2015133-7340
Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)
Phenological growth stages of saffron plant (Crocus sativus L.)
according to the BBCH Scale
Horacio Lopez-Corcoles1, Antonio Brasa-Ramos2, Francisco Montero-García2, Miguel Romero-Valverde2
and Francisco Montero-Riquelme2
1 Instituto Técnico Agronómico Provincial de Albacete (ITAP), Pol. Campollano. Avda. 2ª, 42-B. 02007 Albacete, Spain.
2 Universidad de Castilla-La Mancha, ETSIAM, Campus Universitario. 02071 Albacete, Spain.
Abstract
Phenological studies are important for understanding the influence of climate dynamics on vegetative growth, flowering and
fruiting on plants and can be used in many scientific subjects, such as Agronomy, Botany and Plant Biology, but also Climatology
as a result of the current global interest in climate change monitoring. The purpose of the detailed specific culture descriptions of
the principal growth stages in plants is to provide an instrument for standardization of data recording. To date, there was no coding
method to describe developmental stages on saffron plant (Crocus sativus L.). Because of the increasing world-wide interest on this
crop, a novel growth development code based on the BBCH extended scale is proposed in this paper. Six principal growth stages
were set up, starting from sprouting, cataphylls and flowers appearance, plant appearance and development, replacement corms
development, plant senescence and corm dormancy. Each principal growth stage is subdivided into secondary growth stages.
Descriptive keys with illustrations are included to make effective use of the system.
Additional key words: developmental phases; replacement corm; nomophylls; cataphylls.
Citation: Lopez-Corcoles, H.; Brasa-Ramos, A.; Montero-García, F.; Romero-Valverde, M.; Montero-Riquelme, F. (2015). Short
communication. Phenological growth stages of saffron plant (Crocus sativus L.) according to the BBCH Scale. Spanish Journal of
Agricultural Research, Volume 13, Issue 3, e09SC01, 7 pages. http://dx.doi.org/10.5424/sjar/2015133-7340.
Received: 14 Jan 2015. Accepted: 21 Jul 2015
Copyright © 2015 INIA. This is an open access article distributed under the Creative Commons Attribution License (CC by
3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Funding: The authors received no specific funding for this work.
Competing interests: The authors have declared that no competing interests exist.
Correspondence should be addressed to Horacio Lopez-Corcoles: hlc.itap@dipualba.es
Saffron spice is obtained from dried stigmas of Cro-
cus sativus L. plant and it is appreciated because of its
colouring, flavouring and aroma capacity (Carmona et
al., 2006). It is the most expensive world-wide spice
and thus it has been called “the red gold” (Poggi, 2009).
Saffron-growing in Spain has been world-wide refer-
enced both in yield and quality; in fact, the best qual-
ity saffron spice is globally recognized to be produced
in the Region of Castilla-La Mancha, Spain (Carmona
et al., 2006). Seasonal weather changes are significant
in these Mediterranean climate areas, and saffron plants
have been able to develop survival mechanisms coping
with adverse conditions derived from higher or lower
temperatures as well as extreme drought events (Ware-
ing & Phillips, 1981; Pérez Bueno, 1988).
In cultivated plants, phenological studies have tra-
ditionally been carried out with the aim of agricultural
application to determine the optimal time to apply
fertilizers, crop protection products (herbicides, fungi-
cides and insecticides) and plant growth regulators,
pruning, pollination techniques, obtaining propagation
material and decision making for the best harvest time.
Until the early 1990s, there was not a homogeneous
code to describe the growth stages in most plants and
crops. Zadoks et al. (1974) published the first decimal
code aiming at standardizing the phenological develop-
ment stages description for similar cereal crops by
using the same codes. Further development derived in
the BBCH (Biologische Bundesanstalt, Bun-
dessortenamt und Chemische Industrie) scale proposed
by Bleiholder et al. (1989) and in the extended BBCH-
scale proposed by Hack et al. (1992). Since then, the
extended BBCH-scale has become a world-wide coding
system commonly used to integrate phenology in ag-
ricultural, horticultural, environmental and meteorol-
ogy and climatic studies (Meier et al., 2009). It has
been broadly accepted for its use in many crops like
cereals (Lancashire et al., 1991), sugar beet (Meier et
SHORT COMMUNICATION OPEN ACCESS

H. Lopez-Corcoles, A. Brasa-Ramos, F. Montero-García, M. Romero-Valverde and F. Montero-Riquelme
Spanish Journal of Agricultural Research September 2015 • Volume 13 • Issue 3 • e09SC01
2
al., 1993) or Citrus spp. (Agustí et al., 1997). The
extended BBCH-scale is a system for a uniform coding
of phenologically similar growth stages of all mono-
and dicotyledonous plant species carried out by a work
team referenced by Enz & Dachler (1997). The entire
developmental cycle of the plants is subdivided into
ten clearly recognizable and distinguishable longer-
lasting developmental phases. These ten principal
growth stages alone are not sufficient to define ex-
actly application or evaluation dates, since they always
describe time spans in the course of the development
of a plant. Secondary stages are used if points of time
or steps in the plant development must be indicated
precisely. In contrast to the principal growth stages they
are defined as short developmental steps characteristic
of the respective plant species, which are passed suc-
cessively during the respective principal growth stage.
They are also coded by using a second digit with fig-
ures from 0 to 9.
The characterization of the phenological stages is
essential for saffron crop production since cultural
practices such as application of crop protection prod-
ucts and herbicides, transplanting and tillage rely to a
large extent on correctly checking certain stages (Vela
et al., 2013). Several authors have deeply described the
morphology and annual cycle of saffron plant (Chrun-
goo et al., 1983; Botella et al., 2002; Carmona et al.,
2006; Poggi, 2009) whilst Molina et al. (2005) codified
the phenological stages of saffron inflorescence buds.
Nevertheless, there are currently no universally used
keys to describe the entire development cycle of this
plant.
ITAP (Agronomy Technical Institute of Albacete)
and the University of Castilla-La Mancha have been
working on agronomy research of saffron crop since
1994, particularly on plant breeding, pathology, me-
chanic cultivation practices, corm processing and
flower forcing methods, as related to its influence on
saffron spice quality (ITAP, 2013). Basing on this back-
ground, the objective of this paper was to describe the
phenological growth and developmental stages of saf-
fron plant according to the extended BBCH-scale to
effectively supplement other studies on saffron cultiva-
tion.
The study of saffron plant phenology described in
this paper is based on twenty years field observation
records (from 1993 to 2013) which were collected from
many farming crops and many field experiments, with
plant material of different ages and cultivated at dif-
ferent sites across the Albacete province, Spain (lat. of
38.7 ± 0.75ºN; elevation range: 610–870 m asl), by the
ITAP Department of Agricultural Technology Extension
and Transfer (ITAP, 2013). A field experiment was car-
ried out in the campaign 2012-13 to better describe in
detail the phenological stages of the saffron plant. The
sample plot was located in a traditional farming area
of Balazote, Spain (lat. 38º55’N, long. 02º06’W, 740
masl), under continental mediterranean climate condi-
tions, with winters of type avena/oats warm and sum-
mers of type maize; the temperature regime is temper-
ate to warm and the humidity regime is dry
mediterranean (Papadakis, 1961). The soil is classified
as Haplic-calcisol in the FAO system and Typic-Cal-
cixerept according to USDA.
The sampling plot was representatively selected from
traditional farms growing saffron crop for commercial
use. It was planted in September 2011 on a 6,000 m2
plot, according to proper tillage commonly used in the
area (de Juan & Lozano, 1991). Corms were planted at
15 cm depth in rows 50 cm apart and planting density
of 40 plants/m2. Planting material derived from local
ecotypes of saffron corms. Although the farm has sprin-
kler irrigation infrastructure, it was never used during
this trial because the rainfall (248.5 mm) from Novem-
ber to April was sufficient to cope with the crop water
requirements. Phenology observation was carried out
daily over the whole plot. The phenological stage was
assigned as that of most of the plants, in any case, at
least more than 50%, which had reached that stage
(López, 2004) and the most representative plants were
photographed to describe the most significant pheno-
logical stages. Furthermore, destructive data collection
was recorded every fortnight, that is 13 sampling dates,
with three replicates, from October 1, 2012 to May 9,
2013, covering the period from sprouting up to senes-
cence of the above-ground plant part. Each sampling
consisted on pulling out all the entire plants, with the
exception of roots, in 0.5 × 0.4 m2 plots (10-12 sampled
plants) randomly delimited.
With a view to unifying the criteria existing to de-
scribe the saffron plant cycle, the terms mother corm,
replacement corm or daughter corm and cataphyll are
utilized in this paper basing on Mathew (2003) and
Negbi (2003).
According to field observations and following the
basic principles of the extended BBCH-scale, a phe-
nological scale describing the entire developmental
cycle of saffron (Crocus sativus L.) is proposed.
The study of the biological cycle of saffron plant
starts with the corm in dormancy stage, apparently
showing neither morphological change, nor external
growth, although there do exist internal physiological
and morphogenetic changes (Le Nard & De Hertogh,
1993). Once the corm leaves the dormancy, fibrous
caulogenic roots form a root plate at the base, one or
more shoots subsequently emerge with the leaves and
flowers wrapped by the cataphylls. This currently hap-
pen under the case study environmental conditions from

Spanish Journal of Agricultural Research September 2015 • Volume 13 • Issue 3 • e09SC01
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Short communication: Phenological stages of saffron plant according to the BBCH Scale
Table 1. Growth stages of saffron plant following the extended BBCH-scale
Stage Principal
growth stage Sub-stage Secondary growth stage
0 Sprouting
00 Dormant mother corm. Apical and lateral sprouts are not developed yet.
01 Beginning of bud swelling.
03 Bud swelling complete
05 Roots appearing from the corm.
07 Beginning of bud sprouting.
08 Shoots visible under the soil surface.
09 Emergence: Shoots (cataphylls) breaking through soil surface.
1 Leaf development (assessed at plant level)
10 Leaves (nomophylls) sprouting and unfolding from cataphylls.
11 Leaves (nomophylls) growth at 10% of nal length.
12 Leaves (nomophylls) growth at 20% of nal length.
1X Leaves (nomophylls) growth at X0% of nal length, continues with the same
scheme until sub-stage 18
19 Leaves (nomophylls) growth at 90% of nal length.
4 Development of replacement corms
41 Growth of replacement corms at 10% of nal size.
42 Growth of replacement corms at 20% of nal size.
4X Growth of replacement corms at X0% of nal size, continues with the same
scheme until sub-stage 48.
49 Growth of replacement corms at 90% of nal size.
5Appearance of ower cataphylls
50 Beginning of ower cataphylls. Stigmata are visible at the basal part of the
stem.
55 Flower cataphylls emerging.
57 Flower cataphylls visible above ground, enveloped by its bracts.
59 Flower cataphylls still closed.
6 Flowering
60 First ower tepals visible.
61 10% of maximum ower mass reached.
63 30% of maximum ower mass reached.
65 50% of maximum ower mass reached.
67 70% of maximum ower mass reached.
69 End of owering.
9 Plant senescence
91 Leaves (nomophylls) development completed, foliage still green.
93 Leaves (nomophylls) apices beginning to discolour.
95 50% of leaves yellowish.
96 Roots have dried out and can fall easily.
97 Leaves senescence. Leaves fully discoloured and beginning plant resting.
Mother corm fully dry.
98 Leaves fall off the corm.
99 Replacement corms fully formed.

H. Lopez-Corcoles, A. Brasa-Ramos, F. Montero-García, M. Romero-Valverde and F. Montero-Riquelme
Spanish Journal of Agricultural Research September 2015 • Volume 13 • Issue 3 • e09SC01
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00 05 07 09
10 55 60 61
Figure 1. Selected principal and secondary phenological growth stages of annual cycle of saffron (Crocus sativus L.) corresponding
to sprouting (0: 00, 05, 07, 09), leaf development (1: 10), appearance of ower cataphylls (5: 55), owering (6: 60, 61, 65, 69) and
senescence (9: 97), according to the extended BBCH-scale.
65 69 97
the second fortnight of October on. The above-ground
plant growth derived from sprouting is due to available
reserves in the corm. Flowering occurs from the second
fortnight of October to the first fortnight of November
(ITAP, 2013), and previously to leaf appearance or
simultaneously, since saffron is a hysteranthous plant
(Plessner et al., 1989) whose flowers open before its
leaves depending on the environmental conditions
(Mathew, 1982). Later on, leaves and roots keep on
growing along the period of vegetative activity (Oromí,

Spanish Journal of Agricultural Research September 2015 • Volume 13 • Issue 3 • e09SC01
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Short communication: Phenological stages of saffron plant according to the BBCH Scale
Figure 2. Scheme of the annual cycle and the principal growth stages of saffron (Crocus sativus L.) on a monthly basis, according
to the extended BBCH-scale in Albacete, Spain, based on ITAP (2013). The dash line shows the trend of leaf mass (%) and the dot
line, the trend of corm mass (%).
1. Leaf development
4. Development of replacement corms
6. Flowering 5.
9. Beginning of dormancy
0. Sprouting
45
Mass of leaves
November-March April-May
June June September October
Mass of replacement corms
60%
40%
100%
20%
0%
100%
60%
40%
20%
0%
01 05 09 10 11 13 15 17 19 91 93 95 97 99
47 494341
61 62 64 66 68 69
1992). The base of shoots begins to swell forming the
daughter corms while the mother corm depletes its
reserves. In spring, as diurnal temperatures increase
and soil moisture decrease, the mother corm roots die
and break away, photoassimilates move from the leaves
to the corms and the leaves start to senescence from
the apex to the base; the daughter corms are fully de-
veloped and ready for latency.
For the saffron plant, growth begins with bud swell-
ing and sprouting. The vegetative period is represented
by three principal growth stages corresponding to leaf
development, development of replacement corms and
plant senescence. The reproductive period covers ap-
pearance of flower cataphylls and flowering.
Some stages of the extended BBCH scale do not
apply to saffron plant and must be omitted, like BBCH
stage 2 which is related to the formation of side shoots
or tillering, BBCH stage 3, which relates to stem elon-
gation or rosette growth or shoot development (main
shoot) and finally BBCH stages 7 and 8 which are
related to the development and ripening of the fruit/
seeds respectively, since Crocus sativus L. is a sterile
triploid form making its flowers unable to produce vi-
able seeds for independent sexual reproduction.
Secondary growth stages are referred to by a second
digit in the code (numbered from 0 to 9) and corre-
spond to ordinal or percentage values of plant develop-
ment. For example, for corms development (stage 4),
the scale represented the growth share (%) related to
the final size.
Hence, the extended BBCH-scale proposed for saf-
fron plant only considers 6 out of the 10 principal
growth stages, starting with Sprouting (Stage 0) and
ending with Beginning of dormancy (Stage 9). Four
principal growth stages are involved in vegetative de-
velopment: Sprouting (Stage 0), Leaf development
(Stage 1), Development of replacement corms (Stage 4)
and Plant senescence (Stage 9). The remaining two
principal stages are related to flowering: Appearance
of flower cataphylls (Stage 5) and Flowering (Stage 6).
The entire phenological cycle identified for saffron
plant is characterized in Table 1. It is highly recom-
mended to follow this key with Figures 1 and 2, show-
ing the annual cycle of saffron plant following the
extended BBCH-scale as proposed. Figure 2 shows that
some stages overlap or run concurrently in the saffron
plant cycle (for instance, leaf appearance and flower-
ing, among others); thus, it is recommended that both
stages should be noted separating their codes by a
forward slash.
Álvarez-Ortí et al. (2003) already described the
phenological cycle into six stages according to the

H. Lopez-Corcoles, A. Brasa-Ramos, F. Montero-García, M. Romero-Valverde and F. Montero-Riquelme
Spanish Journal of Agricultural Research September 2015 • Volume 13 • Issue 3 • e09SC01
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Alonso GL, Arghittu A, Astraka K, Betza T, Camba E, Caña-
das W, Carmona M, Cillocco MT, Corona J, Curreli M et
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Le Nard M, De Hertogh AA, 1993. Bulb growth and devel-
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López H, 2004. Modelización de la respuesta agronómica
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morphological and physiological characteristics
observed, although this classification suits the plant
cycle, it is not scaled nor coded for agricultural ap-
plications. The BBCH scale proposed in this paper
for saffron plant will help farmers and technicians
to efficiently cultivate and manage saffron crop.
Furthermore, it will facilitate the exchange of infor-
mation, knowledge and experiences among the sci-
entific community by unifying criteria to describe
the growth and development stages regardless the
area where it might be cultivated. Negbi (2003) re-
ferred that the timing of the transition from vegeta-
tive to reproductive shoot apex differs in Azerbaijan
and Russia, Kashmir or Israel. In Spain it happens
in April-May and flower organs are formed in June-
July (ITAP, 2013). Crop practices scheduling might
be compared and adapted to local situations accord-
ing to regular phenological codes. It must be outlined
that there is variability in dating and duration of the
presented growth stages in the study area, but these
are mainly due to different agronomy and climate
conditions and not to local ecotypes of saffron which
are not present in Spain so far (Alonso et al., 2007).
The extended BBCH-scale for saffron plant is intro-
duced in this paper for the first time. It can be broadly
applicable because it describes the total of six principal
phenological stages for sprouting (stage 0), leaf ap-
pearance (stage 1), replacement corm development
(stage 4), flower cataphylls appearance (stage 5), flow-
ering (stage 6) and beginning of dormancy (stage 9).
These data should facilitate more effective management
of saffron orchards, defining the optimal time to carry
out the different agricultural tasks and particularly ir-
rigation practices, because the crop coefficients are
directly related to the phenological stages.
Acknowledgements
This paper is the result of the work carried out under
different research projects led by Prof. Dr. José Arturo
de Juan Valero† (in memoriam), with resources and
facilities provided by the University of Castilla-La
Mancha and the ITAP (Agronomy Technical Institute
of Albacete, Spain).We are also grateful for the com-
ments and suggestions of reviewers.
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