Carbon Dioxide Assimilation and Foliar Ion Concentrations in Leaves of Lemon (Citrus limon L.) Trees Irrigated With Nacl or Na2SO4

1993 ◽  
Vol 20 (2) ◽  
pp. 173 ◽  
Author(s):  
RR Walker ◽  
DH Blackmore ◽  
Q Sun

An attempt was made to differentiate between the possible effects of high Cl- or Na+ ions on lemon leaf photosynthesis by treating grafted (Citrus limon (L.) Burm. f. cv. 'Taylor') plants with either NaCl or Na2SO4 to establish different foliar concentrations of Cl- or Na+. The rootstocks, Rangpur lime (C. reticulata var. austera hybrid?) and rough lemon (C. jambhiri), were chosen because Rangpur lime is known to be a good Cl- 'excluder' and rough lemon to be a poor Cl- 'excluder'. The grafted plants were initially treated for 7 weeks with nutrient solution (control) or nutrient solution containing 50 mol m-3 NaCl or 25 mol m-3 Na2SO4, after which time there were only marginal reductions in both photosynthetic rates and shoot growth, with the exception of 'Taylor' lemon on rough lemon roostock treated with NaCl where growth was affected more severely than the other treatments. Salinity levels were then doubled to 100 mol m-3 NaCl and 50 mol m-3 Na2SO4 and the plants treated for a further 8 weeks, causing significant increases in leaf Na+ and/or Cl- concentrations. Mature, 3-4-month-old leaves of 'Taylor' lemon on Rangpur lime rootstock treated with Na2SO4 for this period, contained c. 105 mol m-3 Na+ and c. 10 mol m-3 Cl- and had photosynthetic rates 60% lower than controls. Similar reductions in assimilation rate were seen in leaves on rough lemon roostock treated with NaCl containing c. 195 mol m-3 Cl- and c. 35 mol m-3 Na+. Smaller (35%) but significant reductions in assimilation rate were observed for trees on rough lemon roostock treated with Na2SO4, where the tagged leaves contained c. 40 mol m-3 Na+ and 50 mol m-3 SO42-. Leaf nitrogen concentrations were significantly reduced by treatment of trees with NaCl or Na2SO4 but, apart from small reductions in chlorophyll concentrations, there were no visible symptoms of nitrogen deficiency. Leaf turgor was not adversely affected. The data indicate that both Cl- and Na+ can reduce assimilation rates in salt-stressed lemon leaves, possibly because of poor compartmentation within leaves of either ion. Increases in leaf Na+ and Cl- accounted for 54-96% of the reduction in osmotic potential in 'Taylor' lemon leaves on trees treated with NaCl, whereas increases in Na+ and SO42- accounted for 33-71% of the reduction in osmotic potential in leaves on trees irrigated with Na2SO4. The greater increase in Cl- compared with the net increase of [Na+ + K+] in 'Taylor' leaves on rough lemon rootstocks was offset (65%) by reductions in malic and succinic acids. Proline increased significantly only in 'Taylor' leaves on Rangpur lime roostock treated with Na2SO4.

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 540e-540
Author(s):  
Yusheng Zheng ◽  
Carol J. Lovatt

Rough lemon seedlings [Citrus limon (L)] were hydroponically-cultured in complete Shive's nutrient solution (+K) or in Shive's nutrient solution with potassium omitted (-K) for a period of eight months. Fresh and dry weight of whole -K plants were reduced 4-fold (P<0.01). Nitrogen metabolism was monitored during this period in young, fully expanded leaves. Results showed that leaves of -K plants accumulated 2.5-fold more NH3-NH4 + than +K plants (P<0.01) and exhibited a concomitant increase in both activity of the de novo arginine biosynthetic pathway (2.5-fold) and free-arginine concentration (3.5-fold; P<0.001). Leaf proline content of -K plants increased 1.6-fold (P<0.05), while putrescine content increased 10-fold. Arginine decarboxylase activity was accelerated in -K plants.


HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1161f-1161
Author(s):  
John D. Lea-Cox ◽  
Irwin E. Smith

Pine bark is utilized as a substrate in citrus nurseries in South Africa. The Nitrogen (N) content of pine bark is inherently low, and due to the volubility of N, must be supplied on a continual basis to ensure optimum growth rates of young citrus nursery stock. Three citrus rootstock (rough lemon, carrizo citrange and cleopatra mandarin) showed no difference in stem diameter or total dry mass (TDM) when supplied N at concentrations between 25 and 200 mg ·l-1 N in the nutrient solution over a 12 month growing period. Free leaf arginine increased when N was supplied at 400 mg·l-1 N. The form of N affected the growth of rough lemon. High NH4-N:NO3-N (75:25) ratios decreased TDM when Sulfur (S) was absent from the nutrient solution, but not if S was present. Free arginine increased in leaves at high NH4-N (No S) ratios, but not at high NH4-N (S supplied) ratios. Free leaf arginine was correlated with free leaf ammonia. These results have important implications for reducing the concentration of N in nutrient solutions used in citrus nurseries and may indicate that higher NH4-N ratios can be used when adequate S is also supplied.


2007 ◽  
Vol 10 (4) ◽  
pp. 400-411 ◽  
Author(s):  
Yan Zhu ◽  
Yongchao Tian ◽  
Xia Yao ◽  
Xiaojun Liu ◽  
Weixing Cao

Bragantia ◽  
2012 ◽  
Vol 71 (3) ◽  
pp. 394-399 ◽  
Author(s):  
Djeimi Isabel Janisch ◽  
Jerônimo Luiz Andriolo ◽  
Vinícius Toso ◽  
Kamila Gabriele Ferreira dos Santos ◽  
Jéssica Maronez de Souza

The objective of this research was to determine growth and dry matter partitioning among organs of strawberry stock plants under five Nitrogen concentrations in the nutrient solution and its effects on emission and growth of runner tips. The experiment was carried out under greenhouse conditions, from September 2010 to March 2011, in a soilless system with Oso Grande and Camino Real cultivars. Nitrogen concentrations of 5.12, 7.6, 10.12 (control), 12.62 and 15.12 mmol L-1 in the nutrient solution were studied in a 5x2 factorial randomised experimental design. All runner tips bearing at least one expanded leaf (patent requested) were collected weekly and counted during the growth period. The number of leaves, dry matter (DM) of leaves, crown and root, specific leaf area and leaf area index (LAI) was determined at the final harvest. Increasing N concentration in the nutrient solution from 5.12 to 15.12 mmol L-1 reduces growth of crown, roots and LAI of strawberry stock plants but did not affect emission and growth of runner tips. It was concluded that for the commercial production of plug plants the optimal nitrogen concentration in the nutrient solution should be 5.12 mmol L-1.


2005 ◽  
Vol 21 (3) ◽  
pp. 317-328 ◽  
Author(s):  
E. V. J. Tanner ◽  
V. K. Teo ◽  
D. A. Coomes ◽  
J. J. Midgley

To investigate whether seedlings of ten dipterocarp species differed significantly in terms of growth and mortality or whether species were not significantly different and could be considered ecologically similar, seedlings were grown, two per pot, in two experiments: (1) where the two seedlings were of equal height (30 cm); and (2) where one seedling was 10 cm shorter than the other. Seedlings were grown in a shade house with 15% above-canopy light in a 50:50 forest soil–sand mixture and were watered frequently; pots were placed so that seedling density was 130 seedlings m−2 of ground. In the first experiment there were 45 pairwise combinations of species when seedlings were 30 cm tall (AB, AC, AD,…. BC, BD…IJ; where A, B, C…J signify different species); each combination was replicated 10 times so there were 450 pots with 900 seedlings. In the second experiment there were 100 pairwise combinations of species and size e.g. Aa (30 cm A with 20 cm a), Ab (30 cm A with 20 cm b), each combination was replicated 10 times hence there were 1000 pots with 2000 seedlings. After 22 mo 79% of the initial 2900 seedlings survived; on average they had grown 42 cm (i.e. to 72 cm tall from their initial 30 cm). The most frequent outcome of competition-trials between different sized individuals (784 of 1000 trials) was that the initially taller seedling of each pair ‘won’ (it was the taller or surviving seedling). When 900 of these trials (setting aside, Aa, Bb, Cc etc.) were analysed as 45 comparisons between species with different sized individuals (Ab and aB are one interspecific comparison for these purposes), initial height determined the outcome in 23 cases (even in some competitions between light hardwood species and heavy hardwood species); in 6 cases a species (mostly light hardwoods) behaved as a ‘dominant’ – they usually won even if they were smaller initially. We found few significant differences between species in: initial seedling heights; leaf nitrogen concentrations; and specific leaf areas when they were grown in similar conditions, and these attributes were not correlated with growth rates. The similarity of seedlings of different species meant that often a height difference of just 10 cm was enough to determine the outcome of a pairwise competition-trial in high seedling densities and light equivalent to that in forest gaps.


2005 ◽  
Vol 54 (4) ◽  
pp. 571-571 ◽  
Author(s):  
P. Ramachandran ◽  
J. Agarwal ◽  
A. Roy ◽  
D. K. Ghosh ◽  
D. R. Das ◽  
...  

1972 ◽  
Vol 25 (1) ◽  
pp. 77 ◽  
Author(s):  
RD Court ◽  
WT Williams ◽  
MP Hegarty

The effects of several single mineral nutrient deficiencies on the free amino acid composition of S. sphacelata, grown in water culture, have been examined. Most deficiencies result in an accumulation of the free amino acids. Severe copper deficiency causes a large increase in the alanine content of the leaf. Nitrogen deficiency causes decreases in almost all amino acids.


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