SIMNIC-CRAIOVA, ROMANIA

University of Craiova

 

Studies concerning the heredity of  some  characteristics of the corn-cob

 

Bonea, D., Urechean, V.

                                    vioricaurechean@yahoo.com

 

Corn is a allogam plant whose great production are obtained especially on the basis of heterozys. In this paper we intend to prove to which extent the heterozys could contribute to  the creation of new valuable corn hybrids. With  this aim in view it was achieved the direct dialel   hybridation  of five corn inbred lines and the analysis of the behaviour of simple hybrids obtained ( concerning certain characteristics of the corn-cob) was made on the basis of the capacity relation ( CR) calculated after the formula of  M. Jost (1976):

            CR=F1-Max.P    where Max P is maximum parent.

                    1(P2-P1)

                    2 

The results concerning the difference between F1 hybrids and parentsŐ average (F1-x ; table 1 ) emphasize a strong heterozys  for all the characteristics of the corn-cob and especially for: the weight of the corn-cob at Lc406x Lc407 (222g ) and Lc402xLc406 ( 215,7g ) hybrids; for the length of the corn-cob at Lc402xLc 406 (8,35 cm ) and  Lc402x Lc407 (6,5 cm ) hybrids; for the number of grains/ corn-cob at Lc402xLc406 (524 ) and Lc406x W153R (444,5 )

The presence of Lc402xLc406 hybrid is obvious for all the three characters studied.

Due  to the obtaining  of some negative differences between F1 and parentsŐ average we can say that there is a non-heterozys effect in the case of number of grains per corn-cob at Lc403xLc407 (-77,5 )and Lc407xW153R (-7,0 ) hybrids.

From the centralization of data regarding the capacity relation (table 1 ) it results that: for corn-cob weight, eleven hybrids are positive and nine are negative; for corn-cob length, ten hybrids are positive and ten are negative; for the number of grains on corn-cob, ten hybrids are positive and ten are negative.

From the point of view of capacity relation (CR ),positive hybrids are considered valuable and will be promoted through  improvement programs in order to create corn hybrids valuable from a trade point of view.

 

 

 

 

 

 

 

 

 

 

 

 

Table  1.          The difference between F1 and parentŐs average and capacity relation of some simple corn hybrids

 

 

No.

Hybrid

Corn-cob weight ( g )

Corn-cob length (cm)

Number of grains per corn-cob

F1-

CR

F1-

CR

F1-

CR

1

Lc403xLc402

26.5

+0.74

5.05

-0.83

205

-0.68

2

Lc406xLc402

193

+26.57

5.75

-22.0

428

+1.56

3

Lc407xLc402

195

-194

5.7

-3.38

166.5

+29.2

4

W153RxLc402

138

-5.43

3.8

-1.11

147.5

+1.47

5

Lc402xLc403

86

-0.15

3.25

+0.18

167

+0.36

6

Lc406xLc403

137.5

+0.28

2.3

-0.08

252

-0.13

7

Lc407xLc403

68.8

-0.31

3.55

+1.46

48.5

-0.62

8

W153RxLc403

34.2

-0.46

1.06

+0.10

137.5

-0.24

9

Lc402xLc406

215.7

+27.8

8.35

+32.4

524

-2.43

10

Lc403xLc406

92.5

+0.14

3.6

-0.44

202

+0.30

11

Lc407xLc406

155.3

-18.4

2.05

-0.95

286.5

-0.77

12

W153RxLc406

135.4

-2.07

2.55

-0.64

391.5

-2.64

13

Lc402xLc407

207

+206

6.5

+4.0

283.5

-50.5

14

Lc403xLc407

74.5

+0.25

0.55

+0.62

-77.5

+1.60

15

Lc406xLc407

222

+26.75

4.95

+3.71

384.5

+1.38

16

W153RxLc407

158

-3.38

3.5

-6.0

231

+3.27

17

Lc402xW153R

187.8

+4.07

5.8

+2.22

324.5

-4.45

18

Lc403xW153R

64.5

-0.02

4.25

-3.47

98.5

+0.45

19

Lc406xW153R

147

+2.34

5.95

+2.83

444.5

+3.13

20

Lc407xW153R

129.5

+2.59

2.50

+4.0

-7.0

-1.12

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SIMNIC-CRAIOVA, ROMANIA

University of Craiova

 

 

            Dependence of corn production on pluviometric regyme

 

            Urechean, V., Bonea, D.

                       

                                    vioricaurechean@yahoo.com

 

 

The influence of rain gauge regyme upon the production of corn grains have been studied in the course of five years, using as biological material  the following hybrids: Neptun         ( FAO 300-400 ), Olt ( FAO 400-500 ), F376 ( FAO 500-600 ) cultivated in the geographical area of Simnic- Craiova, Romania.

The study of relations between the production   of corn grains and the   rain gauge regyme  had two phases: sowing time- the appearance of stigmata and  sowing time- physiological maturity (28%grains humidity ).

For a better interpretation of experimental data there have been   calculated several statistic indicators: variability coefficient ( v% ), regression coefficient (b), correlation coefficient (r ) and also the average productions for every hybrid studied.

Concerning the variability of average data ( table 1 ), there  are registered  middle values for the sum of rainfall  until the appearance of stigmata ( 11.6% for Neptun; 11.9% for Olt; 11.6% for F376 ) and low values for the sum of rainfall until the physiological maturity (9.0% for Neptun; 9.6% for Olt and 9.4% for F 376 ).

Hybrid

Appearance of stigmata

Physiological maturity

                                           Variability coefficient ( v% )

Neptun

Olt

F 376

11.6

11.9

11.6

9.0

9.6

9.4

                                             Regression coefficient (b )

Neptun

Olt

F 376

+16.4

+19.2

+22.1

+43.0

+40.7

+47.5

                                            Correlation coefficient ( r )

Neptun

Olt

F 376

+0.488

+0.686

+0.682

+0.875

+0.930*

+0.956*

 

Table1.            Dependence of grains production on rain gauge regyme illustrated by the statistic indicators v%, b, and r

 

 

The dependence of corn grains production on rain gauge regyme  ( table 1 ) registers coefficients of positive correlation, both until the appearance of stigmata ( +16.4; +19.2; +22.1 ) and until the physiological maturity ( +40.7; +43.0; +47.5 ).

The rata/year of the  increase or decrease of corn production  depending on the rain gauge regyme, reflected by the coefficient of line regression ( b ) enters on the same  positive line as the correlation  coefficient ( r  ).

In order to analyze the   dependence of maximum   and minimum productions ( of each hybrid studied in 2002-2006 period ) on rain gauge regyme  ( table 2 ) there were established the deviations from the average which were expressed  in absolute and percentage values.

 

Hybrid

Kg/ha

Year

Appearance of stigmata

Physiological maturity

( % )

( % )

Neptun

9260/2005

2108/2003

+168.9 ( +83.9 )

-57.1 ( -28.3 )

+252.5 ( +72.6 )

-153.5 ( -44.2 )

Olt

11970/2005

2239/2003

+175.3 ( +87.6 )

-51.2 ( -25.7 )

+280.9 ( +79.2 )

-160.6 ( -45.3 )

F 376

11050/2005

2455/2003

+172.1 (+84.6 )

-55.9 (-27.5 )

+271.3 ( +77.1 )

-159.7 ( -45.4 )

Table 2            Dependence of maximum and minimum production on rain gauge regyme in 2002-2006 period

 

 

We can observe that maximum productions have been obtained in 2005 for all the hybrids, having values of 9260 Kg/ha for Neptun, 11970 Kg/ha for Olt, and 11050 Kg/ha for F376, in this way being able to enter on the coordinates of an ascending line according  to maturity groups. The most obvious contribution to the obtaining of maximum productions was the sum of rainfall registered until the appearance of stigmata: Neptun ( +168.9 mm, +83.9% in comparison with the average ), Olt  ( +175.3 mm, +87.6% in comparison with the average ), F 376 ( +172.1 mm, +84.6% in comparison with the average ).

Minimum productions have been obtained in 2003 for all hybrids, having values of 2108 Kg/ha for Neptun, 2239 Kg/ha for Olt and 2455 Kg/ha for F 376.

Minimum productions have been influenced   by the sum of  rainfall, meaning negative deviations from the average, until the appearance of the stigmata and especially until the physiological maturity : Neptun ( -153.5 mm; -44.2% in compassion with the average ); Olt (-160.6 mm; -45.3% in comparison with the average ); F376 ( -159.7 mm, -45.4% in comparison with the average ).

From the analysis of these data we can observe that the production of grains have been  positively influenced by the rain gauge regyme, the most obvious relation  being emphasized between the rainfall from the sowing-physiological maturity period, especially for Olt hybrid

The analysis of dependence of grains production on rain gauge regyme was detailed by correlation coefficients between production of grains and rain gauge regym of each month from April to August ( table 3 )

We have established that the most variability ( v% ) was registered for rain gauge regym in July.

The rainfall registered in April have influenced slowly negative the productions of grains.

Beginning with May the rainfall registered have influenced positively the production of grains for all the three hybrids studied and especially, all the hybrids have responded high significant positively to the sum of rainfall registered in August.

 

Table 3            Dependence of grains productions on month rain gauge regyme illustrated by correlation coefficients ( r )

 

 

Month

Average 2002-2006

Vatibility coefficient (v% )

Neptun

( r )

Olt

( r )

F 376

( r )

April

52.9

53.5

-0.068

-0.074

-0.119

May

70.0

58.8

+0.074

+0.242

+0.288

June

77.6

54.1

+0.560

+0.648

+0.607

July

109.7

62.4

+0.686

+0.722

+0.768

August

97.0

52.0

+0.986

+0.982

+0.984