CHISINAU, MOLDOVA
Academy of Sciences of Moldova
The estimation of the mutual influence of maize seeds with different germination capacity in pure and mixed genotype groups by changing seed germination capacity during storage --Maslobrod, SN, Corlateanu, LB, Ganea, AI, Grati, MI, Savasteeva, NL During long-term storage of crop seeds, their germination capacity deteriorates, which negatively affects both quantitative and qualitative productivity indices of the crops grown from those seeds. This effect can be decreased by regulation of the abiotic environment, in which the seeds are stored: temperature, light, gas composition, etc. (Nicolaeva, Lyanguzova, Pozdova, 1999). We set a goal of determining whether this effect is influenced by the co-storage of seeds of different genotypes and different initial germination capacity, and if the effect can be decreased, and possibly evaded, by making a special "seed mix" for storage.

The seeds of the local maize hybrids with good initial germination capacity (GG) — M450, P458 and M215A, and bad germination capacity (BG) — M411 and M215 were used in the experiment. The seed mixes were made of the seeds of two genotypes with different germination capacity in a 1:1 proportion — M411+M450; M411+P458; M411+M215A; M215+M450; M215+P458; M215+M215A, and pure groups of seeds of a single genotype — M450; P458; M215A; M411; M215.

In the mixed groups, the seeds of one of the genotypes (BG) were marked with a marker, to make it possible to separate them from the seeds of the other genotype during the following separate germination. The seeds were stored in glass jars with a tight lid. The jars were kept in darkness at +20 C. During storage, the germination capacity was periodically checked with the intervals of 1.5 (1), 3.0 (11) and 4.5 (111) months. The seeds were couched at +25 C. The number of seeds of each variant was no less than 100. In the end of the experiment (stage 111) the chromosome aberrations (%) were counted in 300-700 cells of the germs’ roots.

Results and discussion. The seeds of different hybrids, but with the same initial germination capacity and group, showed a similar effect of storage on germination. This allowed us to combine the variants of such seeds and calculate their average germination capacity for each storage period. The seeds of mixed and pure groups were shown to have different germination dynamics. In the mixed group, the germination of the seeds with GG remained practically unchanged during the experiment, while germination capacity of the seeds with BG decreased drastically (Fig.1). Student value, calculated by studentized test, was t1-11 = 2.95 and t1-111 = 3.92 for periods 1 and 11 and 1 and 111, respectively. At the same time, according to Fig. 2, in the pure groups, the germination capacity of seeds with GG decreased considerably by the end of the experiment (t1-11 = 1.68 and t1-11 = 7.96). Germination capacity of seeds with BG in such groups also decreased considerably (t1-11 = 1.66 and t1-11 = 4.63). The impression is that in the mixed groups the seeds with GG maintained their high germination capacity during the experiment at the expense of the seeds with BG, triggering the decrease of their germination capacity (negative feedback). Apparently, this causes a more rapid decrease of germination capacity of the seeds with BG in the mixed groups than in the pure groups (germination capacity values by periods in mixed groups (%) — 62.0; 51.0 and 45.5; in the pure groups — 64.3; 56.3; 52.3). A totally different pattern is observed in the case of a pure group of seeds with different initial germination capacity. In this case, the seeds with GG maintained a high germination capacity, at the level of the initial one during the experiment, and the seeds with BG showed an increase in germination capacity (Fig. 3). One can assume that the seeds with GG activate the seeds with BG (positive feedback). This confirms our previous data on germination capacity and germination energy stimulation of maize seeds with BG at the expense of the seeds with GG when couched together (Maslobrod et al., 2001; Maslobrod et al., 2002). A hypothesis which has already had its first evidence that the effect of stimulation appears due to electromagnetic (physical) and allelopathic (chemical) channels of interaction of the seeds germinating together, was stated. Apparently, similar mechanisms act during interaction of dry seeds during their co-storage, and become apparent later when the seeds are couched separately. In this case, some kind of seed "memory" is brought about. The stimulation of seeds with BG by the seeds with GG in pure groups, and oppression of the seeds with BG by the seeds with GG in the mixed groups can be considered a result, on the one hand, of the concurrence of the frequencies of electromagnetic fields of the seeds in the group (resulting in a resonance), and, on the other hand, of non-concurrence of these frequencies (no resonance). The work of the chemical mechanism can be pictured, apparently, using as an example a group of seeds with only GG, where the decrease of the seeds germination capacity during storage can be caused by their poisoning by their own products of interaction.

The decrease of the germination capacity of seeds with GG in the pure groups correlates with the increase of chromosome structural abnormalities of the germs of these seeds. The average number of chromosome aberrations of the germs of the seeds with GG was 3.8% in pure groups, 3.1% (t=3.89) in mixed groups. This parameter was the same in both groups (3.8% and 3.7%) of the seeds with BG.

Thus, seed germination capacity is much influenced by their storage in pure or mixed genotype groups. The first data have been obtained. The research should be continued, as it allows us to demonstrate that the sowing quality of bad seeds can be substantially improved by their storage in a mixture with good seeds.

Figure 1. Dependence of germination of the seeds upon their storage periods in the mixture of seeds of different genotypes with different initial germination. GG — the seeds with good germination; BG — the seeds with bad germination; I, II, III — storage period (1.5; 3.0; 4.5 months).

Figure 2. Dependence of germination on their storage periods of seeds of a single genotype and with equal initial germination.

Figure 3. Dependence of germination of the seeds of a single genotype upon their storage period in the mixture of seeds with different initial germination.
 
 


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