In addition, we have also been awarded the “IDEAL BUSINESS” certificate for two years in a row.
Pepper is a vegetable that can be grown exclusively from seedlings in the majority of Central European countries. No matter if you wish to grow peppers in the open field or in greenhouses, you have to produce seedlings first. Pepper requires high temperatures, high air and soil humidity. It prefers soil with a neutral reaction that are rich in nutrients and permeable. This warm climate plant requires a site that would be sheltered from wind. Staking is recommended in order to protect the bushes from strong wind and heavy rainfall.
The quality control process
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The ‘Tesla F1’ pepper variety produces large, sweet, dark yellow fruit. It is a vegetable with a great potential. It belongs to medium early varieties that are recommended for cultivation in greenhouses and tunnels. The large block-type fruit whose length to width ration is about 10 to 8.5 are almost ideally cuboid. They consist of four chambers surrounded by the extra thick flesh, 8 to 9 mm. They look exceptionally appetizing and weigh 220 grams on average. The fruit is pale, green-white at the beginning. As they turn dark yellow, you can start the harvest. The ‘Tesla F1’ pepper crops are recommended for the fresh market. They taste great in salads and constitute a vitamin-rich addition to sandwiches and make a great match with dips and cold sauces during barbecue parties. The flesh of the ‘Tesla F1’ peppers is perfectly suited for pickling and freezing.
All our seeds must pass a four-stage quality control process.
Stage three starts with sowing seeds in selected control plots. That way we obtain valuable, exact information concerning their germination that must be maintained at an appropriate level. Simultaneously, the varietal identity of each species is checked at this stage.
The professional seeds that we offer here represent the highest possible quality. They meet the highest requirements thanks to the restrictive checks that they regularly undergo. These seeds stand out with excellent germination rate and seedlings’ resistance to pathogens that plague the given species. The professional cultivars are characterized by an excellent taste and high productivity. The professional seeds that we offer here are adjusted to the soil and weather conditions that prevail in Central Europe, but can be successfully grown in other regions too. The carefully selected seeds are the key factor in every culture.
All seeds we sell are subject to a multi-level quality control checks and only then are carefully packed and dispatched. Our products have been awarded numerous certificates and comply with the highest standards of the European Union. Our employees are experienced gardeners who are more than happy to answer your every question.
The important restrictive role of the seed envelopes in the germination of dormant WT seeds could be demonstrated by the germination of embryos when these envelopes were removed (data not shown). Since microscopic analysis did not detect any consistent defects at the level of the aleurone and hyaline layer (data not shown), this restriction may be imposed essentially by the testa itself, which is in agreement with the maternal inheritance of both testa defects and germination behavior. Several mechanisms may explain how the chemical and structural composition of the testa determine the germination capacity of the seeds. The oxidized flavonoid polymers may play a major role in limiting not only water entry, as seen in legumes, but also oxygen supply to the embryo, for example, as reported by Corbineau and Côme (1993) for cereals, and by contributing to the mechanical resistance of the testa. They may also inhibit the leaching of germination inhibitors out of the seed, as proposed for charlock (Edwards, 1968, 1969). Whether one or all of these phenomena participates in the control of Arabidopsis seed germination remains to be investigated.
Effect of dry storage on dormancy release. Germination was scored 2 d (A), 9 d (B), 18 d (C), and 27 d (D) after seed harvest. The WT ecotypes are indicated with an asterisk. The genotypes are ranked from the left to the right in the direction of the more to the less dormant at d 9 of storage (B) and are grouped under the motif corresponding to their ecotype background, as presented in Figure Figure3 3 A.
Effect of dry storage on seed longevity. The germination of seed lots after 45 months of dry storage at room temperature was assessed. The WTs are indicated by an asterisk. The genotypes are ranked from left to right as the smallest to the highest percentage of normal seedlings (black bars). For total germination percentage, they are grouped under the motif corresponding to their ecotype background, as presented in Figure Figure3 3 A.
In Arabidopsis, it is difficult to monitor water uptake because of the water-holding capacity of the mucilage layer. Therefore, we used the uptake of tetrazolium salts by the embryo to assess the permeability of the testa. The embryo and the aleurone layer stain red upon entry of the tetrazolium solution into the viable seed, but stay whitish when the dye does not penetrate. This pattern of staining is shown in Figure Figure2C, 2 C, with tt12 as an example of a genotype taking up the dye and and Ws as one that does not. None of the genotypes with a brown seed coat (such as the WTs, tt10, and gl2) were stained with tetrazolium, leading to dark yellow seeds at the end of the assay (Fig. (Fig.2A, 2 A, column T). In contrast, the pigmentation mutants and those exhibiting a structural testa abnormality (such as ats and ap2) reacted positively; their seeds developed a light red to dark red color depending on the genotype. The onset of impermeability of the WT seeds to tetrazolium during the later phases of seed development was concomitant with the appearance of the brown pigments during seed desiccation (data not shown). This impermeability decreased very slowly during after-ripening at a rate much slower than overall dormancy release by after-ripening. Moreover, it was not affected by cold treatments. The occurrence of germination indicates that the permeability to tetrazolium salts cannot be used to monitor the permeability of Arabidopsis seeds to water. From this assay, we cannot conclude that the testa imposes dormancy in wild-type seeds by limiting water entry.
Most testa mutants showed reduced seed dormancy, as ascertained by a lower requirement for after-ripening and a higher germination rate. In our conditions, the ban seeds exhibited reduced dormancy together with an increased permeability to tetrazolium, which differs from the results of Albert et al. (1997), who showed that ban is more dormant than the WT. These authors postulated that the overaccumulation of pigments in the seed coat is an obstacle to germination. Our vanillin and tetrazolium assays showed that there may not be an overaccumulation of pigments, but rather a replacement of the proanthocyanidin polymers by anthocyanins, which may lead to an increased permeability to tetrazolium. This hypothesis is supported by further analysis of the mutant (Devic et al., 1999).
Seed lots stored for 4 years at room temperature were compared for their ability to germinate and produce normal seedlings. Testa mutants generally showed a reduced germination capacity and a higher rate of seedling abnormalities than their WTs (Fig. (Fig.6). 6 ). The structural mutants ats and ap2 were particularly affected. The degree of seed deterioration was not strictly correlated with dormancy characteristics or with seed size and weight.
The second group is represented by mutants affected in testa structure. The aberrant testa shape (ats) mutant ovules lack two cell layers of the integuments and as a result produce heart-shaped mature seeds (Léon-Kloosterziel et al., 1994). The glabra2 (gl2) mutant has brown seeds but similar defects in mucilage production, testa surface structure, and root hair formation as the ttg1 mutant (Rerie et al., 1994; Masucci and Schiefelbein, 1996). Therefore, ttg1 combines defects of both testa mutant groups. The floral development apetala2 (ap2) mutant has heart-shaped seeds that lack mucilage (Jofuku et al., 1994).
Description of the Seed Phenotypes
The aim of the present study was to analyze the consequence of mutations affecting the testa on the dormancy, germination, and longevity of Arabidopsis seeds. The availability of a large collection of mutants with related testa defects can be expected to give an indication of how these pigments and structural components of the testa affect germination behavior of seeds. In the present report we relate reduced dormancy to the increased uptake of tetrazolium salts and to a reduced thickness of the testa. These results suggest that the permeability and thickness of the testa are affected by the chemical compounds and structural elements altered in the mutants, which may lead to effects on germination.
Seed aging defines the time-dependent deterioration of seed metabolism, leading to the loss of vigor and eventually viability (Walters, 1998). Testa pigmentation was seen to confer a better resistance to solute leakage, to imbibition damage, and to attack by soil-born fungi, thereby improving seed vigor and germination in legumes (Powell, 1989; Kantar et al., 1996). Oxidative stress may also be involved in the aging process. Membrane damage through lipid peroxidation and free radical accumulation were reported to play a major role in this degradation process (Khan et al., 1996b). The antioxidant properties of phenolic compounds, particularly flavonols, are well established (Rice-Evans et al., 1997; Yamasaki, 1997). In Arabidopsis, mutants deficient in flavonoid biosynthesis exhibit a 60% higher level of lipid peroxidation than WT plants when exposed to UVB (Landry et al., 1995). Therefore, it is very likely that seed flavonoids play a protective role against solute leakage, imbibition damage, and oxidative stress. The results presented here, showing that pigmentation mutants exhibit more deterioration than their WTs, are in agreement with this hypothesis. Moreover, the poor storability of ats demonstrates that a drastic structural defect can also be very detrimental for seed viability.