DNIEPROPETROVSK, UKRAINE
Institute of Grain Farming, UAAS The role of weather conditions in donor plant cultivation in corn anther culture --Satarova, TN, Chernousova, NM The process of embryoid induction in anther culture is determined not only by the period of anther cultivation in vitro, but also by the period of donor plant growing. The environment factors change physiological features of initial plants and can promote the increase or reduction of androgenic response. During the work on anther cultivation of corn at the Institute of Grain Farming, UAAS some genotypes were studied over a few years under identical soil conditions of donor plant growing and uniform technique of cultivation in vitro. This allows characterization of the variability of embryoid induction depending on the weather conditions, which changed from year to year.

Donor plants were grown in a field in 1993-1999 in the southeast of Ukraine (Dniepropetrovsk). Annually complete mineral fertilizer N60P60K30 was applied by plowing. In the spring the field was treated with soil herbicide harness 3 l/hec. Sowing was carried out at the end of April - the beginning of May. The cutting of tassels for anther culture was made in July. Anther planting in vitro was on nutrient medium YP according to Genovesi, AD and Collins, GB (Crop Sci 22:1137-1144, 1982) after cold pretreatment at a temperature of 8 C for 14 days. Anthers from 5-7 plants were taken for one variant of the experiment. Anthers were used at the stage of young bicellular pollen grain. Anthers at the appropriate stage of development were isolated from sites on the central core of each tassel. The percentage of responsive anthers (anther response) and the number of embryoids per 100 anthers cultivated were registered after 6 weeks of cultivation in vitro. The experimental results were compared with meteorological data of the corresponding years. The coefficients of pair and multiple correlations between the change of weather characteristics and two parameters of androgenic induction were counted.

The frequencies of anther response and numbers of embryoids per 100 anthers for various genotypes in different years are submitted in Tables 1 and 2.

Table 1. Anther response (%) for corn genotypes in different years of investigations.
 
Genotype Years             F/F0.01**
  1993 1994 1995 1996 1997 1998 1999  
And44 0.64a* -  12.14b 0a 1.08a 1.19a 0a 85.24/3.02 
H99xWf9 0a 0.30a 1.32b 0.37a 0a - - 12.85/3.32
Wf9xH99 0.34a 0.56a 3.78b - 0a -  0a 26.99/3.32
B14xWf9 17.70a 3.43b 6.92c 0.29e 3.93b - 1.71be 169.12/3.02
Wf9xB14 - 2.94a 10.99b 0.26c 0c - 1.94ac 190.50/3.32
Wf9xLH148 - 5.68a - 0b - 15.86c - 56.45/4.61
And44xLH148 1.07a 0.13ac 2.78b 2.20b 0.24ad -  0.07cd 11.30/3.02
Wf9xAnd44 0.21a - 4.41b - 0a - 2.38c 45.75/3.78 
Average 2.75a 0.94b 3.06c 0.65be 0.71bf 1.48d 0.46def 126.8/2.80 

* - Data for one genotype with the same letter are not significant at the level 0.01. ** F - the criterion of Fisher for the given genotype, F0.01 - standard criterion of Fisher at the level 0.01.

Table 2. Number of embryoids per 100 anthers for corn genotypes in different years of investigations.
 
Genotypes Years             F/F0.01**
  1993 1994 1995 1996 1997 1998 1999  
And44 0.64a* - 29.57b 0a 1.16a 1.63a 0a 325.03/3.02
H99xWf9 0a 0.30a 1.70b 0.37a 0a - - 17.72/3.32
Wf9xH99 0.34a 0.64a 6.33b - 0a - 0a 56.38/3.32
B14xWf9 38.46a 5.25b 18.26c 0.32de 7.40b - 2.86be 463.31/3.02
Wf9xB14 - 3.73a 28.13b 0.44a 0a - 5.08a 190.50/3.32
Wf9xLH148 - 8.40a - 0b - 27.24c - 113.19/4.61
And44xLH148 1.32a 0.13b 6.85c 3.20c 0.95ab - 0.07b 28.62/3.02
Wf9xAnd44 0.24a - 8.32b - 0a - 8.25b 103.60/3.78
Average 5.45a 1.32b 6.88c 0.93b 1.08b 2.30d 1.13b 358.5/3.18

* - Data for one genotype with the same letter are not significant at the level 0.01. ** F - the criterion of Fisher for the given genotype, F0.01 - standard criterion of Fisher at the level 0.01.

The data testify to the significant influence of such factors as " year " on both parameters of induction in anther culture of corn. Each genotype was studied within 3-6 years, and for each genotype, except B14xWf9, and for the average of genotypes the year 1995 was outstanding among the years investigated. For hybrid B14xWf9 the most positive was the year 1993, though the other genotypes had not shown high results that year. We designed coefficients of pair correlation between parameters of androgenic induction and such weather characteristics as average annual temperature of air, average monthly temperatures of air in May, June and July, sums of average monthly temperatures of air in May - June, May - July, maximal temperatures of air in May, June, July, humidity of air in May, July, the sum of rainfalls in September - December of a previous year, sums of rainfalls in January - April, May, June, July, May - June, May - July of a current year, and the changes of these characteristics in comparison with long-term norms. The majority of such coefficients had small values (<0.7) and were non-significant. For further analysis we have selected only those coefficients, which even for one of the genotypes were at the level of 0.7 and higher. There were coefficients of pair correlation between parameters of androgenic induction and maximal temperature of June, the sum of rainfalls in January - April and the sum of rainfalls in May - July (Table 3).

Table 3. The coefficients of pair correlation between the parameters of androgenic induction in corn anther culture and weather characteristics .
 

 
 

Genotype

 Number of years Coefficient of pair correlation between anther response and Coefficient of pair correlation between number of embryoids per 100 anthers and
    max temp of June sum of rainfall in max temp of June sum of rainall in
      January-April May-July   January-April May-July
And44 6 0.720 0.806** -0.578 0.733* 0.809** -0.589
H99 x Wf9 5 0.706 0.800* -0.738 0.729 0.808* -0.686
Wf9 x H99 5 0.684 0.758 -0.804* 0.706 0.781* -0.777
B14 x Wf9 6 0.168 -0.408 0.181 0.278 -0.311 0.120
Wf9 x B14 5 0.631 0.834* -0.506 0.727 0.873** -0.452
And44 x LH148 6 0.743** 0.469 -0.731* 0.772* 0.709* -0.680

* - significant at the level 0.1; ** - significant at the level 0.05.

The coefficients of pair correlation between parameters of androgenic induction and maximal air temperature of June for And44 and And44xLH148 were approximately +0.7 and were significant at the level of probability 0.1. For other genotypes, except B14xWf9, the coefficients of correlation were +0.6 - +0.7, but were not significant because of the limited number of years investigated. The pair correlation between parameters of androgenic induction and the sum of rainfalls in January - April for And44 and And44xLH148 was high, positive and significant at the level 0.05 (r = +0.8). The coefficients of the same dependence for other genotypes, except B14xWf9, and the correlation with anther response for And44xLH148 also were +0.7 - +0.8, but were not significant. The coefficients of pair correlation between parameters of androgenic induction and the sum of rainfalls in May - July for all genotypes, except B14xWf9, were negative (r= -0.5 - -0.8) and significant for Wf9xH99 and And44xLH148 for anther response.

The coefficients of multiple correlation between parameters of androgenic induction and joint influence of weather conditions, such as maximal air temperature of June and the sum of rainfalls in January - April, maximal temperature of air in June and the sum of rainfalls in May - July and sums of rainfalls in January - April and May - July, are shown in Table 4. These coefficients for all genotypes, except B14xWf9, were +0.6 - +0.9. Depending on considered connection for And44 they were significant at levels 0.01, 0.05 and 0.1, for H99xWf9 - at the level 0.1. For Wf9xH99 five coefficients of six, and for Wf9xB14 three of six were significant at the level 0.1, for And44xLH148 four coefficients of six were significant at the level 0.05, one - at the level 0.1.

Thus, the cultivation of donor plants in different years under the same conditions of field growing and cultivation in vitro leads to significant distinctions in androgenic induction for the same genotype. The most probable weather factors affecting the androgenesis through a donor plant are maximal temperature of June, the sum of rainfalls in January - April and the sum of rainfalls in May - July. For the first two weather characteristics mentioned above a positive correlation with parameters of androgenesis for a number of genotypes was noticed and for the last one - the negative. The coefficients of multiple correlation show that the interaction of these elements especially maximal air temperature of June and the sum of rainfalls in January - April influences the reaction of genotypes. From these positions it is possible to explain, why the year 1995 was the most favorable for induction. That year the maximal air temperature of June (38 C) and the rainfall amount in January - April (284.3 mm) were the highest for the years investigated, and the rainfall amount in May - July (84.3 mm) - the lowest. Possibly, the increased amount of moisture in soil at the time of sowing, the effect of rainfalls in January - April, ensures favorable conditions for initial and further plant growth and development. The high maximal temperature of June and the lowered rainfall amount in the period of vegetation before cutting tassels in July create stress conditions, which promote transition of pollen grains from the gametophytic to the sporophytic way of development. In June - July meiosis occurs in corn plants, and the effect of stress factors in the period of meiosis was always considered to be decisive for transition on the androgenic way of development in cereals (Batygina, TB, Chlebnoe zerno, Nauka, 1987).

Table 4. The coefficients of multiple correlation between the parameters of androgenic induction in corn anther culture and weather characteristics.
 

 
 

Genotype

 Number of years Coefficient of multiple correlation between anther response Coefficient of multiple correlation between number of embryoids per 100 anthers
   
 
 
 
 
 
 

max temp of June and

 the sum of rainfall in January-April and May-July
 
 
 
 
 
 

max temp of June and

 the sum of rainfall in January-April and May-July
    the sum of rainfall in January-April the sum of rainfall in May-July   the sum of rainfall in January-April the sum of rainfall in May-July  
And44 6 0.922*** 0.824* 0.875** 0.931*** 0.837* 0.879** 
H99 x Wf9 5 0.882* 0.877* 0.913* 0.899* 0.867* 0.902*
Wf9 x H99 5 0.850 0.902* 0.922* 0.874* 0.894* 0.917*
B14 x Wf9 6 0.527 0.243 0.441 0.672 0.300 0.330
Wf9 x B14 5 0.842 0.615 0.882* 0.896* 0.790 0.899*
And44 x LH148 6 0.760 0.888* 0.796* 0.876** 0.885** 0.854**

* - significant at the level 0.1; ** - significant at the level 0.05.; *** - significant at the level 0.01.

The marked tendencies of the influence of weather conditions on androgenic efficiency of corn donor plants with various degrees of probability are inherent to different investigated genotypes. Only the reaction of B14xWf9 was not typical for donor plant response.

In that way, not only the conditions of anther cultivation in vitro, but also certain weather factors of field donor plant growing are capable of determining the androgenic ability in corn.
 
 

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

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