SIMNIC-CRAIOVA, ROMANIA
Agricultural Research Station Morpho-physiological aspects of seedlings in a local maize population under abiotic stress conditions --Urechean, V Local populations of maize represent a source of genetic variability for reducing genetic vulnerability to the biotic and abiotic stress factors.

P21 is a local population collected from the Tia Mare-Corabia area which has been maintained in Agricultural Research Station Simnic`s collection of maize populations for twenty years by multiplication in plots isolated in space. Open pollination assured the genetic variability; both yellow grain and red-purple grain plants were identified in this population.

P21 with yellow grain is the object of this study .The grains were put under abiotic stress conditions in order to germinate:

Five grains/Petri dish x 5 repetitions, covered with 40g dry and well chapped soil and then watered with the following solutions: MT(control)-watered with water, 10 mM NaCl, 100 mM Na Cl, 10 mM PRO (proline), 100 mM PRO, 10 µ M ABA (abscisic acid), 100 µ M ABA, 100 mM MAN(mannitol), 500 mM MAN, 2 ml/Petri dish, every 48 hours, for 14 days, in laboratory conditions (temperature varied between 15 C and 18 C). When temperature attained 22 - 23 C, the watering rate was 10 ml solution/Petri dish (every 48 hours) until transfer of the seedlings into vegetation dishes.

The timing of the coleoptile`s appearance was determined for each treatment variant (Table 1).

Table 1. Timing of coleoptile appearance for a local maize population (P21-yellow grain) under varied stress conditions.
 
Treatment 
Number of days from the experiment`s beginning
5
6
7
8
9
12
19
% coleoptile`s appearance
Difference from MT (control)

%
Mt (control)
1
4
5
10
16
18
  
72
100
10 mM Na Cl  
2
4
6
11
18
19
76
105
100 mM Na Cl   
2
2
3
5
17
16
68
94
10 mM PRO  
5
6
13
16
20
21
84
116
100 mM PRO
1
1
1
2
5
13
11
52
72
10 µM ABA  
2
6
11
13
    
52
72
100 µM ABA  
1
7
13
15
    
60
83
100 mM MAN  
3
3
8
9
12
  
48
66
500 mM MAN      
1
5
14
  
56
77

At the 5-6 leaf stage the stress becomes visible, the percentage of wilted leaves varying between 3% (MT) and 31% (100 µMABA) (Table 2). At this time, one week, the percentage of wilted leaves increases to 73% in 500 mMMAN treatment variant.

Table 2. Plant height and leaf wilting for stressed seedlings of maize.
 
Treatment 
No. of leaves
No. of wilted leaves

I
% dry wilted leaves

I
Plant's height cm I
Number of wilted leaves

II
Wilted leaves II

%
Plant's height cm 

II
Difference of height (II-I) cm
MT(control)
6.0
0.2
3.0
49.3
1.6
26
53.2
3.9
10 mMNaCl
6.5
1.6
25
57.0
2.7
41
63.1
6.1
100mMNaCl
5.5
1.5
27
37.8
2.6
47
39.8
2.0
10mM PRO
6.0
1.4
23
55.2
2.5
41
61.2
6.0
100µM ABA
4.5
1.4
31
37.8
1.9
42
38.1
0.3
100mM MAN
6.5
1.1
17
52.6
2.8
43
65.0
12.4
500mM MAN
4.5
1.3
28
49.1
3.3
73
59.6
10.5

Plant height appears to be stimulated by high mannitol.

In the 5-6 leaf stage a red purple stalk coloration was obsreved on the first basic internodes in response to stress factors. We used a grading scale of the stalk coloration from zero to 2 where zero=the lack of purple coloration and 2=full coloration.

Mannitol determined the most intensely purple coloration of the stalk, with the color intensity increasing with the mannitol concentration. Seedling survival was highest in the 100 mMMAN (92days) and 10 mMPRO (89days) treatment variants.

The plants selected represent sources of valuable genes for the programs to improve maize response to stress factors.
 
 

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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