Study on agrotechnical elements of winter cereals grown after stubble predecessor.Self-sequence of winter wheat varieties for cultivation as self-sequence crop
2007
Tonev, T. | Tsenov, N. | Kostov, K. | Todorov, I. | Panajotov, I.
The investigation was carried out during 20042006 in the trial field of Dobroudja Agricultural Institute General Toshevo. Twenty-four wheat varieties from the three quality groups (A, B1 and B2) were investigated after two previous crops: fodder maize (check variant) and wheat, using the state standard Sadovo 1 as a check variant. Sowing was done at the beginning of the optimal agrotechnical term. All elements of agrotechnics were in accordance with the official technology for cultivation. The only difference after both predecessors was pre-sowing soil tillage. It was established that the modern common winter wheat varieties realized, on the whole, higher yields after predecessor wheat under the conditions of Dobroudja region, without occurrence of yield-reducing epiphytoty. High significance of the interactions 'Genotype x Year'and 'Genotype x Type of predecessor'was established in the three quality groups. Wheat demonstrated higher variability of yield when grown in self-sequence cropping; this was most evident in the varieties from group A, and the varieties from group B2 were, on the whole, with the highest level of plasticity to the environment and the agronomic factors. When growing wheat in self-sequence cropping, 1000 grain weight decreased within the group with a mean of 5-6 %, and hectoliter weight of grain with a mean of 0.51.0 kg. In favorable years the values of hectoliter weight can exceed the values obtained after more favorable predecessors. To evaluate common wheat availability for self-sequencing cropping, coefficient KA was used calculated by the formula , where RYS is the relative yield according to a standard variety, RYCP is the relative yield according to a check predecessor, and VC is the yield variation coefficient after predecessor wheat. The descending ranking of the first 10 investigated varieties was the following: Kristal Todora Kristy Pliska Iveta Antonovka Karat Bolyarka Slaveya Aglika. According to this approach, varieties Lilia, Zlatina, Milena and Demetra were least suitable for growing after predecessor wheat.
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