some physiological studies on salinity tolerance for some citrus rootstocks rasha arafa anwar ...

24 Pages·2017·0.23 MB·English

by  Dalia Ali

SOME PHYSIOLOGICAL STUDIES
ON SALINITY TOLERANCE FOR SOME
CITRUS ROOTSTOCKS

By

RASHA ARAFA ANWAR MOHAMED
B.Sc. Agric. Sci. (Cultural Project Management), Higher Institute for
Agricultural cooperation, 2003

THESIS
Submitted in partial fulfillment of the
Requirements for the Degree of

MASTER OF SCIENCE
In
Agricultural Sciences
(Plant Physiology)

Department of Agricultural Botany
Faculty of Agriculture
Cairo University
EGYPT

2016
ABSTRACT

The present study was conducted in the nursery of Horticulture
Research Institute, Giza, Egypt under greenhouse conditions on Volkamer
lemon (Citrus volkameriana Ten. And pasq.) "VOL" and Cleopatra
mandarine (C. reticulata Blanco) "CM” rootstocks seedlings at transplanting
stage during 2014 and 2015 seasons.
This study aimed to assess the response of seedlings to saline water
under some bio-stimulants treatments and it's impact on the growth of the
seedlings as well as physiological performance and leaves elements content.
The obtained results indicated: i) Both VOL and CM stocks seedlings
vegetative growth , physiological performance as well as leaf N, P, K, Mg,
Fe, Zn, and Mn concentrations were significantly improved, whereas Na and
Cl contents were reduced, when treated with proline, salycilic acid, glycine
betaine or humic acid, and irrigated with well water (cont. treat.) or saline
water 1500 ppm. ii) Moreover, CM rootstock was more tolerant to high
levels of saline water as compared to VOL stock.
iii) It can be used of CM stock in citrus seedlings production at low levels of
saline water without bio-stimulants applications, and with it's at the high of
salinity level up to 1500ppm. On the contrary, VOL can be used in this
respect with bio-stimulants substances under saline water conc. 1500 or
2000ppm as well.

Keywords: Citrus rootstocks, Volkamer lemon, Cleopatra mandarine,
proline, humic acid, Glycine Betaine and Salycilic acid.
INTRODUCTION
Citrus is the largest horticultural crop in Egypt. It is the major
fruit crop industry, during the last few years, and harvested area
increased rapidly from year to year ," about 530415 Fed. in
2014"*.Whereas, the fruiting acreage of citrus occupies about 440706
Fed. producing 4,402,180 Tons.
It's well known that, agricultural expansion and other uses needs
a great amount of available water. But there are many interpretation so
for search to find unconventional solutions to this problem by
optimizing water resources is to employ these points :a) Raising
efficiency of field irrigation system. b) Reuse of agricultural drainage
water, c) Searching for about other resources of water and d) the
development of research methods in the field of breeding and
production assets and plant species tolerant to drought and salinity
stress….etc.
Additionally, the rapid expansion of irrigated agriculture,
efficient use of the limited water resources in arid and semi arid
regions is becoming more and more vital. However, water salinity is a
major problem due to its negative influence on the yields of many
crops. Except for halophytes, water salinity partially inhibits the
growth of most plants.

*According to Annual Report of Agri. Min. - Egypt (2014).
Four reasons that are usually introduced a solely responsible for
reduction of plant growth under salts stress conditions. These are
briefly the (i) Osmotic stress caused by reducing the availability of
external water, (ii) Specific ion effects, (iii) Nutritional imbalance
caused by these ion-toxicity effects, and (iv) A combination of any two
of the above mentioned factors. Citrus is salt-sensitive. The response to
salinity depends on several factors like rootstock–scion combinations,
irrigation system, soil type and climate, etc. Changing one or more of
these factors (with the same irrigation water) could produce entirely
different results. Similar to most other plants, salinity reduces citrus
trees’ growth and causes physiological disorders.
The increase in the salinity level reduced and delayed seed
germination, plant height, stem diameter, number of leaves /seedling,
fresh top and root biomass (Singh et al., 2004). Salinity had negative
effects on: leaf defoliation, leaf injury, vegetative growth and leaf and
root mineral contents (Amen Amal et al., 2008). High salt
concentrations caused a great reduction in growth parameters such as
fresh and dry weights of shoots and roots (Balal et al., 2011). Salinity
had a restrictive effect on rate of root elongation. Roots dry weight for
tested rootstocks cvs. had similar trend to that of growth rate by
increasing irrigation water salinity concentrations. (Karem et al.,
2013). As salinity increased, all measured characteristics of plants after
4.5-month growth except of Na uptake, proline content, and electrolyte
leakage decreased ( Zarei and Paymaneh, 2014).
In spite of, many citrus rootstocks species suffer a decline in
growth while exposed to salinity stress, nevertheless, certain rootstocks
as Cleopatra mandarin, Troyer citrange and sour orange are better
able to exclude the uptake and translocation of these potentially
damaging ions to the shoot and are more tolerant to salinity. Whereas,
the relative tolerance of these various rootstocks appeared to be due
primarily to their ability to exclude Na and Cl from the leaves,
(Mickelbart et al., 2007).
Bio-stimulant application "such as humic acid , amino acids and
related products have great impacts on plant growth. Its involving
increase nutrient uptake, tolerance to drought and extremes
temperature, activate of beneficial soil microorganisms, as well as
facilitate the availability of soil nutrients particularly in alkaline soils
and those have low organic matter (Russo, 1959 and Shaban and
Mohese, 2009). Also, humic materials may increase root growth in a
similar manner to auxins (, O'Donnell, 1973, Tattini et al. 1991 and
Senaratna et al. 2000). Moreover, bio-stimulants can enhance the yield
and fruit quality of citrus and it becomes a positive factor to minimize
utilization of inorganic and chemical fertilizers.
It is safe for human and environment and using them was
accompanied with reducing the great pollution occurred on our
environment as well as for producing organic foods for export. It can
serve as useful components of integrated plant nutrient supply systems
which help in increasing crop productivity by increasing soil
organism's activity and so increasing availability of nutrient elements
and consequence their uptake, moreover these substances can stimulate
plant growth through hormonal action or antibiosis.
Generally, the current study, present information and data
regarding the effect of some bio – stimulants applications on growth
and nutrient uptake of Volkameriana and Cleopatra mandarin citrus
rootstocks seedlings under salinity conditions at transplanting stage,
aiming to reduce the damage of salinity on the growth of citrus
seedlings.
REVIEW OF LITERATURE
1. Vegetative growth of citrus seedling
Russo (1959) mentioned that, producing citrus seedlings needs
suitable rootstock, fertile soil media and good agriculture management
such as : Volkamer lemon (Citrus volkameriana) which is used as a
rootstock for citrus, due to its tolerance and its acceptable resistance of
a large scale of citrus diseases. Moreover, it induces the vigor of citrus
seedlings and consequently reduce the time needed in the nursery for
seedling production .
Marco (1977) reported that, Rangpur lime and Cleopatra
mandarin rootstocks are more resistant to salinity than Ponicitrus
trifoliata rootstock and Sour orange was more tolerant to fluctuations
in soil water content than Citrus lime.
Jooika and Singh (1979) stated that, Rangpur lime and
Cleopatra mandarin were the most tolerant when grown in pots with
soil and salts conditions of 2.3 -9.9 mmhos/cm and their growth was
assessed after 120 days.
Rokba et al. (1979) found that, Cleopatra mandarin appeared to
be the most tolerant variety to salinity stress, followed by Poor man
orange rootstock, but Volkamer lemon rootstock was intermediate .
Grieve (1983) concluded that, the most salt tolerant rootstocks
were Cleopatra mandarin, Rangpour lime ,Sweet orange, Carrizo
Citrange and Troyer citrange, respectively.
Caro et al. (1979) found that, trunk" diameter and height" of the
aerial parts, weight of roots and the shoot / root ratio of Troyer
citrange, Cleopatra mandarin and Sour orange rootstocks were
decreased with increasing salinity of irrigation water.
Ragab (1979) mentioned that branches length and dry weight of
leaves, stem and roots of Valencia orange budded on Sour orange
rootstock were progressively depressed with increasing salinity levels.
Rokba et al. (1979) stated that, growth measurements for Sour
orange, Cleopatra mandarin and Rough lemon decreased with
increasing different salinity levels in irrigation water. They added that
excessive accumulation of chloride causes leaf-burn, shoot dieback,
defoliation and finally, the death of entire plant. In addition, the degree
of severity and time in which the symptoms appeared varied with the
variety and salt level used for irrigation water.
Mylonas and McCants (1980) reported that, tobacco (Nicotiana
tabcum) plants grown on filter paper saturated with humic acid
solutions had higher root numbers and total root length than plants
grown on filter paper saturated with nutrient solution or deionised
water.
Rauthan and Schnitzer (1981) reported that, humic substances
positively affected plant growth by increasing soil aggregation,
aeration and permeability.
Schettel and Balke (1983) found that, SA produced in the
rhizomes here of some plants played the role of an allelopathic
chemical and inhibited the growth of the surrounding plants.
Abdel Messih et al. (1984) found that, growth rate of some
citrus rootstock was depressed by increasing salinity levels.
Dasberg et al. (1985) indicated that, salinity of irrigation water
had no effect on Shamouti oranges plant growth in the 1st season,
however, in the 2nd season, the increase in main branch diameter was
retarded by the highest salinity treatment.
Sherif (1985) mentioned that, growth rate as well as dry weights
of leaves, shoots and roots of Sour orange, Cleopatra mandarin, Rough
lemon and Rangpur lime rootstock were depressed by increasing the
salinity level in irrigation water.
Zekri and Parsons (1990) found that, salinity treatments affected
total leaf area and seedling height of Sour orange and Cleopatra
mandarin citrus rootstock grown in fine sand under greenhouse
conditions by 44-55% with all salt treatments. In additions, irrigated
water 40 mM NaCl reduced Sour orange seedlings root and shoot dry
weights by approximately 30%, but did not induce leaf necrosis.
Montaser et al. (1993) indicated that, the increase in salts
concentration proportionally decreased mango seedlings height; stem
thickness, total number of leaves, leaf area and dry matter of leaves,
stem and roots.
Syvertsen et al. (1993) mentioned that, the high salinity
irrigation water reduced tree canopy growth of 6-year-old 'Valencia'
orange trees budded on either Carizo citrange (CC) or sour orange
(SO) rootstocks.
Vallini et al. (1993) reported that, plants treated with 300 mg
kg-1 of humic acid had the heaviest weight of both fresh and dry
shoots; however, doses of 3000 mg kg-1 were highly photoxic and
inhibited the growth of laurel plant.
Combrink et al. (1995) studied : i) the occurrence of Cl- toxicity
symptoms on the leaves, they indicated that Vlokamer lemon rootstock
was the most tolerant to Cl, followed by Roman lemon.ii) Reduced
root and shoot DM with increased chloride concentration, they
obtained that VOL was the most tolerant rootstock followed by RLE.
El-Desouky and Atawia (1998) mentioned that Volkamer lemon
and Rangpur lime rootstocks showed greater salt tolerance than sour
orange and Cleopatra mandarin rootstocks. Whereas, the maximum
tolerable salinity level was determined to be 4000 ppm.
Anjum et al. (2001) reported that, under salinity stress
conditions Cleopatra mandarin and Gadadehi proved to be the most
tolerant, while Kharnakhatta was the least tolerant one and Jattikhatti,
Jambherikhatti and Yuma citrange were moderately salt tolerant.
Liu and Cooper (2002) showed that, salinity had less effect on
root growth than top growth, humic acid treatment enhanced root
growth of salt stressed plants and improved salinity tolerance by
neither increased uptake of the mineral nutrients inhibited by salinity,
nor decreased uptake of the nutrients which were excessive and toxic
in the salinity solution.
Phanuphong and Gregory (2003) showed that, the application of
humic acid has a positive influence in promoting overall tree vigor.
Treated trees were larger and the root system was better developed
than the untreated trees. Other study found that, humic substances have
a very profound influence on the growth of plant roots. When humic
acids and fulvic acids are applied to the soil, enhancement of root
initiation and increased root growth may be observed (Pettit, 2004).
The stimulatory effects of humic substances have been directly
correlated with enhanced uptake of macronutrients, On the contrary,
Pablo and William (2003) stated that, humic acid did not affect papaya
transplant growth (shoot dry weight, shoot height, leaf number, leaf
area and trunk diameter).
Singh et al. (2004) reported that, the increase in the salinity
level reduced plant height, stem diameter and number of leaves per
seedling. The reduction in these parameters was lowest in C. limonia,
followed by C. jambhiri and P. trifoliata., C. limonia was tolerant, C.
jambhiri was moderately tolerant, and P. trifoliata was susceptible to
salinity. On The response of C. jambhiri, C. limonia and Poncirus
trifoliata rootstocks to various levels of soil salinity conditions.
Camara-Zapata et al. (2004) noticed that, Salinization reduced
plant dry weight more in sour orange than in Cleopatra mandarin
plants. Growth of both cultivars was not recovered totally in the relief
period, since relative growth rates of recovered plants were lower than