SCIENTIFIC WORKS OF THE LITHUANIAN INSTITUTE OF
HORTICULTURE AND LITHUANIAN UNIVERSITY OF AGRICULTURE.
SODININKYSTË IR DARÞININKYSTË. 2006. 25(3). 283–291.
BIOMASS PRODUCTION, DRY WEIGHT PARTITIONING
AND LEAF AREA OF APPLE ROOTSTOCKS UNDER
DROUGHT STRESS
Jurga SAKALAUSKAITË, Darius KVIKLYS,
Juozas LANAUSKAS, Pavelas DUCHOVSKIS
Lithuanian Institute of Horticulture, Kauno str. 30, LT-54333 Babtai,
Kaunas distr., Lithuania. E-mail: [email protected]
The influence of water deficiency on apple (Malus domestica Borkh.) rootstocks
was investigated at the Lithuanian Institute of Horticulture in 2005. Trial was conducted
with 10 rootstocks: Antonowka seedling, MM.106, M.26, B.118, M.9, P 60, P 59, P 2, B.396,
and P 22 under three soil moisture regimes. After an initial period of growth under wellwatered conditions the amount of irrigation was gradually reduced in order to simulate
natural drying in the soil. Biometric indices – assimilation area, fresh and dry weight of
leaves, shoots and roots were measured after 5 weeks of the experiment. Moderate drought
stress suppressed the accumulation of fresh and dry weight in all investigated rootstocks,
except seedling rootstock, where accumulation of fresh and dry weight was induced.
Moderate drought also induced the growth of leaves of seedling rootstock, MM 106, and
P 59. Severe drought negatively affected the accumulation of fresh and dry weight of all
apple rootstocks. Reduction to 50% was determined in comparison to control plants.
Severe drought induced premature leaves senescence and shedding. Water stress altered
partitioning of dry mass, especially under severe drought stress. Higher allocation of total
plant dry weight into shoots and roots instead of leaves was observed under severe
drought stress. According to fresh and dry weight accumulation, P 22, B.118, P 60 and
seedling rootstocks were the most drought resistant. M.26, M.9, P 2 and B.396 rootstocks
were the most sensitive to water deficiency. According to leaf area changes, M.26, P 2 and
B.396 rootstocks were the most drought sensitive. Moderate drought stress did not affect
leaf area of seedling, MM.106, B.118, M.9, P 59, and P 22 rootstocks.
Key words: Malus x domestica, fresh and dry weight, rootstock, water stress.
Introduction. Different rootstock genotypes have different adaptability to various
climatic and soil conditions. More dwarfing rootstocks have shallower root system
and usually in commercial growing they are used to be irrigated. Nevertheless,
rootstock performance under water deficiency is different. Though, there is only
limited information on the drought tolerance of apple rootstocks (Wertheim, 1998),
some researches established that P 22 rootstock seems to be more suitable to soils
with a low content of water than P 16 (Klamkowski, Treder, 2002). There are reports
that M.111 and M.26 rootstocks show good drought tolerance (Atkinson et al., 2000;
283
Ferree, Carlson, 1987). Drought tolerance of M.9 rootstock is also highly evaluated
(Fernandez et al., 1997; Klamkowski, Treder, 2002). There was established that
P 60 rootstock under Lithuanian climatic conditions does not need irrigation
(Duchovskis et al., 2000; Kviklys, Petronis, 2000).
Periods of soil water deficit of varying length and severity commonly occur
during the growing season. Drought is one of the most severe environmental stresses
and affects almost all the plant functions (Kazuko Yamaguchi-Shinozaki et al., 2002).
Since water stress can reduce plant growth, soil water availability may thus be an
important production determinant (Schulze, 1986). Water deficit can affect plants in
different ways. In the frame of “physiological window” mild drought induces in
plants regulation of water loss and uptake, allowing maintenance of their leaf relative
water content within the limits where photosynthetic capacity and quantum yield
show little or no change. The most severe form of water deficit is desiccation –
when most of the protoplasmic water is lost and only a very small amount of tightly
bound water remains in the cell (Yordanov, 2003).
Productivity of crops under drought stress condition is strongly related to the
processes of dry matter partitioning in the plant and the spatial and temporal root
distribution (Kage et al., 2004). Water stress, however, can affect the growth of
each plant organ differently, and the pattern of dry mass accumulation within the
plant may thus be altered (Atkinson et al., 1998). The development of crop leaf area
is controlled by the amount of assimilates allocated to the leaves and determines
radiation interception and therefore transpiration and assimilate production (Jones,
1992; Campbell, Norman, 1998). An optimal partitioning of dry matter between root
and shoot, and the further separation of aboveground dry matter between the vegetative
and generative organs has crucial importance for crop yield under drought stress
conditions. Drought stress mostly reduces leaf growth and increased dry matter
allocation into the root fraction, leading to a declining shoot/root-ratio (Wilson, 1988).
The yield effect of this adaptation process, however, depends strongly upon time
and extends of drought stress (Campbell, Turner, 1990).
The aim of the present study was to investigate biometric changes of apple
rootstocks induced by drought stress grown under natural weather condition, but
with controlled water regime.
Materials and methods. 1-year-old apple rootstocks (‘Antonowka’ seedling,
MM.106, M.26, B.118, M.9, P60, P59, P 2, B.396, P 22) were planted in early
vegetative growth phase in plastic pots. 10 different rootstocks were potted in each
pot. Potted trees were grown outdoors under natural weather conditions and watered
equally until midsummer. Potted rootstocks were transferred to plastic greenhouse
when drought stress treatment was initiated. Three soil moisture regimes were created:
20–30 kPa (control), 40–50 kPa and >70 kPa. Rootstocks were grown under such
conditions for 5 weeks. Moisture content in the soil was measured by tensiometer.
Biometric measurements were done at the end of experiment. Whole plants of
each rootstock were harvested, and then the individual plant samples were divided
into stems, leaves and roots. Roots were washed and cleaned from organic debris.
Plant tissues were oven-dried at 105°C for 24 h to determine dry weight. Leaf area
meter WinDias (U.K) was used for assimilation area measurements. Experiment was
carried out in four replications.
284
Statistical analysis was performed using one-way and two-way ANOVA. Means
were separated by Fisher’s Least Significant Difference (P≤0.05 and P≤0.01) and
Duncan’s Multiple Range t-test procedure (P≤0.05).
Results. Drought stress significantly decreased the accumulation of total fresh
and dry weight on the average of all rootstocks (Table 1). Significant differences
were recorded for all watering regimes.
T a b l e 1. The total fresh and dry weight of apple rootstocks under
different drought treatment, g (the average of ten
rootstocks)
1
l e n t e l ë.
Bendra poskiepiø þalia ir sausa masë, esant skirtingiems drëgmës
reþimams, g (deðimties poskiepiø vidurkis)
Fresh weight / Žalia masë
Dry weight / Sausa masë
20–30 (control / kontrolë)
40–50
>70
90.97
64.54
51.56
41.92
30.43
25.43
LSD05/R05
LSD01/R01
5.56
7.37
2.67
3.53
Drought treatment /Sausros režimas, kPa
According to accumulation of fresh and dry weight apple rootstocks responded
differently to drought stress (Table 2, 3). The accumulation of fresh weight was
inhibited in all rootstocks exposed to moderate water stress, except seedlings that
accumulated about 30% more of fresh weight as compared to control plants
(20–30 kPa). At the same regime fresh weight accumulation in rootstocks M.26,
M.9 and P 2 was suppressed by 50%.
T a b l e 2. Total fresh weight of apple rootstocks exposed to different
water stress, g
2
l e n t e l ë.
Obelø poskiepiø bendra þalia masë, esant skirtingiems drëgmës
reþimams, g
Rootstock / Poskiepiai
Seedling / Sëklinis
MM.106
M.26
B.118
M.9
P 60
P 59
P2
B.396
P 22
Drought treatment / Sausros režimas, kPa
20–30 (control / kontrolë)
40–50
>70
62.51 a
93.32 a
74.05 a
87.08 a
130.57 a
98.32 a
97.50 a
95.12 a
92.11 a
79.17 a
79.54 a
67.81 ab
42.75 b
71.94 ab
70.34 b
73.43 a
88.08 a
45.11 b
55.51 b
50.90 a
52.64 a
49.28 b
41.50 b
40.46 b
56.18 b
62.20 a
55.06 b
44.44 b
56.18 b
57.75 a
Means in the line marked with the same letter do not differ significantly at P≤0.05
Ta paèia raide paþymëtos reikðmës eilutëje ið esmës nesiskiria (P≤0,05).
285
Under severe drought (>70 kPa), total fresh weight accumulation of rootstocks
MM.106, M.26, M.9, P 59, P 2 and B.396 significantly decreased as compared to
control plants. There were no significant differences between all watering regimes
in total fresh weight of P 22, seedling, and P 60 rootstocks.
Similar tendencies of dry weight variation were determined too. At the end of
experiment, the dry weight accumulation of stressed apple rootstocks tended to
decrease with the intensity of drought stress (Table 3). Under the severe stress at the
end of the experiment, total dry weight accumulation in rootstocks dropped to 50%.
At the end of the experiment, total dry weight of M.9, P 2, M.26 and B.396
rootstocks under moderate and severe drought significantly decreased. The total dry
weight of P 59 and MM.106 rootstock significantly decreased only in severe drought.
There were no significant differences between all watering regimes in the total dry
weight of P 22, seedling, B.118 and P 60 rootstocks.
T a b l e 3. Total dry weight of apple rootstocks exposed to different
water stress, g
3
l e n t e l ë.
Rootstock / Poskiepiai
Seedling / Sëklinis
MM.106
M.26
B.118
M.9
P 60
P 59
P2
B.396
P 22
Obelø poskiepiø bendra sausa masë, esant skirtingiems drëgmës
reþimams, g
Drought treatment / Sausros režimas, kPa
20–30 (control / kontrolë)
40–50
>70
29.08a
43.50a
34.59a
40.70a
61.16a
45.55a
41.29a
44.24a
42.32a
36.79a
37.92a
30.59a
20.61a
34.09a
35.06b
33.63a
38.30a
21.32b
27.87b
24.94a
26.74a
24.53a
21.23a
21.12a
29.54b
29.02a
24.46b
21.62b
25.94b
30.08a
Means in the line marked with the same letter do not differ significantly at P≤0.05
Ta paèia raide paþymëtos reikðmës eilutëje ið esmës nesiskiria (P≤0,05).
Water stress altered the partitioning of rootstock dry mass (Fig. 1). Partitioning
of total plant dry weight to leaves of seedling, MM.106 and M.9 rootstocks were
greater under moderate water stress. The accumulation of total dry weight to shoots
was more induced in rootstocks P 59 and P 2. Partitioning of total plant dry weight
to roots of B.396 and P 60 rootstocks was greater under moderate water stress.
While partitioning of total dry mass of rootstocks M.26 and B.118 was not altered
under moderate water stress. Higher allocation of total plant dry weight to shoots
and roots instead to leaves was considerably expressed in all rootstocks under severe
drought stress.
286
F i g. 1. Dry weight partitioning into various organs of apple rootstocks exposed to
different water stress, %
1
p a v. Sausos masës pasiskirstymas ávairiose obels poskiepiø dalyse, %
287
The moderate drought stress stimulated growth of leaves of seedling, MM.106,
M.9, P 59 and P 22 rootstocks as compared to control plants (Fig. 2). Other rootstocks
B.118, P 60, M.26, B.396 and P 2 shed accordingly 10%, 20%, 40%, 45% and 50%
of the leaves under moderate water stress. The severe drought induced premature
leaves senescence and shedding of all rootstocks. It was determined 30-80% leave
loss of various rootstocks exposed to severe drought. According to leave area changes
the most sensitive rootstocks to drought stress were M.26, B.396 and P 2.
F i g. 2. Changes in leaf area of apple rootstocks under moderate (40-50 kPa) and
severe (>70 kPa) drought stress. The values are expressed as a percentage variation
of total leave area in (20-30 kPa) control treatment, %
2 p a v. Poskiepiø lapø ploto pokytis, esant skirtingiems drëgmës reþimams.
Vertës iðreikðtos kaip procentinis pokytis poskiepiø, augusiø normaliomis drëgmës
sàlygomis, %
Discussion. The drought treatment resulted in large decrease in total fresh
weight of all apple rootstocks. Rootstock fresh weight declined with increasing soil
drying for the majority of rootstocks tested. Even moderate drought stress inhibited
the accumulation of fresh weight, except seedling rootstock. The total fresh weight
decreased significantly for semi-dwarf M.26 and dwarf M.9, P 2 and B.396 rootstocks,
though in some experiments higher drought resistance of M.26 was recorded (Atkinson
et al., 1998). Consequently, drought-induced decreases of rootstocks fresh weight
were accompanied by reduction in total dry weight. Total dry weight of all rootstocks
declined with increasing soil drying. Tested rootstocks can be grouped into two
separate groups according to decreased total dry weight at the end of experiment:
rootstocks MM.106, M.26, B.118, M.9, P 60, P 59, P 2 and B.396, which dry weight
declined by 40-50%, and another group – seedling rootstock and P 22, which dry
weight declined by 10-20 %, compared to control plants. Higher drought resistance
of P 22 rootstock was noted in Polish trials, though it was less resistant as M.9
(Klamkowski, Treder, 2002). Our study results showed opposite tendency – super
dwarfing P 22 was more resistant to water deficiency as dwarfing and semi dwarfing
rootstocks.
Soil moisture changes not only affect the plant biomass dry weight, but also the
distribution of assimilates to roots and shoots (Amdt et al., 2001; Ranney et al.,
1990). Under the influence of hormones synthesized in the leaves and roots in response
to drought, changes occur in the allocation of assimilates, the ratio of shoot to root
288
growth is altered (Larcher, 1995). In our investigation drought also affected dry
matter partitioning, resulting in more dry matter partitioning to root or shoot systems.
Even moderate water stress induces intensive dry weight accumulation in shoots or
roots of rootstocks P 59, P 2 and B.396. Usually above ground plant growth decreased
by changes in biomass partitioning that favoured root system development. Thus
plants can exploit the limiting water resource in a more efficient way by increasing
the proportion of water absorbing root biomass relatively to the water-loosing leaf
biomass (Duan et al., 2005; Li, 1999; Yanbao Lei et al., 2006; Zhang et al., 2004).
Such tendencies were noted in our trial too.
Under severe drought stress apple rootstocks had lower values of leaf area than
the well-watered controls, indicating that drought induced premature leave senescence
and shedding. Under moderate water stress differences in the growth of leaves were
recorded between various rootstocks: seedling rootstock increased its leaf area by
50%, MM.106 – 10%, M.9 – 5%, P 59 – 25%, P 22 – 6%, while other rootstocks
M.26, B.118, P 60, P 2, B.396 shed leaves to some extent. Dwarf rootstocks P 2 and
B.396 decreased their leaf area to a great extent under moderate water stress. Among
the 10 used apple rootstocks, leaf area of super dwarfing P 22 and dwarfing P 60
were least affected by drought stress. Good performance of the latter rootstock in
not irrigated orchards was noted in our previous trials (Duchovskis et al,. 2000;
Kviklys, Petronis, 2000). This could be ascribed to their low stomatal conductance,
which enabled the plants to control water status restrictively when water uptake by
the root was curtailed as the soil dried. According Atkinson (2002) for the range of
rootstocks examined, stomatal conductance was generally greater for the more growth
invigorating rootstocks than for the restricting.
There was no relationship between rootstock drought hardiness and ability of
the rootstock to control scion vigour. Semi dwarf M.26, dwarf M.9, P 2 and B.396
rootstocks were more sensitive to water deficiency as super dwarf P 22 and P 59
rootstocks. Such findings are confirmed by other trials too (Atkinson, 2000).
Our results confirm the existence of genetic differences in the fresh and dry
matter accumulation, dry matter allocation and leave area as affected by water stress.
These variations in drought responses may be used as criteria for rootstock selection
and tree improvement.
Conclusions. Rootstock fresh and dry weight declined with increasing soil
drying. According to fresh and dry weight accumulation, M.26, M.9, P 2 and B.396
rootstocks are the most drought sensitive. MM.106 and P 59 rootstocks reacted
negatively only in severe drought conditions. P 22, B.118, P 60 and seedling rootstock
were most resistance to water deficiency.
According to leaf area changes, M.26, P 2 and B.396 rootstocks were the most
drought sensitive. Moderate drought stress did not affect leaf area of seedling,
MM.106, B.118, M.9, P 59, and P 22 rootstocks. Thought severe drought conditions
decreased leaf area of all rootstocks, P 22 and P 60 rootstocks were less affected.
Higher allocation of total plant dry weight into shoots and roots instead of leaves
was observed under severe drought stress.
Acknowledgement. This work was supported by Lithuanian State Science
and Studies Foundation under project FIBISTRESS.
289
Gauta
2006 07 11
Parengta spausdinti
2006 08 02
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SODININKYSTË IR DARÞININKYSTË. MOKSLO DARBAI. 2006. 25(3).
283–291.
SAUSROS SUKELTO STRESO ÁTAKA OBELØ POSKIEPIØ BIOMASEI,
SAUSOS MASËS PASISKIRSTYMUI IR LAPØ PLOTUI
J. Sakalauskaitë, D. Kviklys, J. Lanauskas, P. Duchovskis
Santrauka
Tyrimø tikslas – nustatyti vandens trûkumo átakà ávairiems obelø poskiepiams.
Bandymai atlikti Lietuvos sodininkystës ir darþininkystës instituto Augalø fiziologijos
laboratorijos vegetacinëje aikðtelëje. Tirti sëkliniai, MM.106, M.26, B.118, M.9, P 60, P 59,
P 2, B.396 ir P 22 poskiepiai. Tyrimo metu palaikyti skirtingi dirvos drëgmës reþimai:
20–30 kPa (kontrolë), 40–50 kPa ir >70 kPa. Tyrimo pabaigoje nustatyta, kiek sukaupta
þalios ir sausos masës, ir iðmatuotas lapø plotas. Vidutinis sausros sukeltas stresas
(40–50 kPa) slopino þalios ir sausos masës kaupimàsi visuose poskiepiuose, iðskyrus
sëkliná; jame þalios ir sausos masës kaupimasis buvo skatinamas (sukaupë iki 30% daugiau
nei kontroliniai augalai). Vidutinis sausros sukeltas stresas taip pat paskatino sëklinio
poskiepio, MM.106, M.9, P 59 ir P 22 poskiepiø lapø augimà, o kiti poskiepiai pradëjo mesti
lapus. Stiprus sausros sukeltas stresas neigiamai paveikë ir þalios, ir sausos masës kaupimàsi
visuose poskiepiuose. Nustatyta, kad palyginti su kontroliniais poskiepiais, þalios ir
sausos masës sumaþëjo iki 50%. Sausrai sukëlus didelá stresà, visø poskiepiø lapai vyto ir
krito per anksti. Sausros sukeltas stresas pakeitë ir sausøjø medþiagø pasiskirstymà ávairiose
poskiepiø dalyse. Intensyvus sausros sukeltas stresas skatino daugiau sausøjø medþiagø
kauptis ðaknyse ar ûgliuose nei lapuose. Pagal þalios ir sausos masës kaupimàsi nustatyta,
kad jautriausi sausrai yra M.26, M.9, P 2 ir B.396 poskiepiai, atspariausi – P 22, B.118, P 60
ir sëklinis poskiepiai. Pagal lapø ploto pokytá jautriausi sausrai yra M.26, P 2 ir B.396
poskiepiai. Vidutinis sausros sukeltas stresas neturëjo átakos sëklinio, MM.106, B.118,
M.9, P 59 ir P 22 poskiepiø lapø dydþiui.
Reikðminiai þodþiai: Malus x domestica, poskiepis, sausa ir þalia masë, sausros
sukeltas stresas.
291