Yield response of winter wheat varieties to low inputs

In five-year varietal trial the set of varieties was studied in conditions of ecological cultivation according to IFOAM (International Federation of O rganic Agriculture Movements) principles and Methodological Instruction for Ecological Agriculture of Ministry of Agriculture of CR. Trials were a par t of national investigation of varieties for the List of Recommended Variet ies preparing by the Central Institute for Supervising and Testing in Agric ulture, Brno. The trials with wheat varieties are conducted on many Czech p laces at various cultivation intensity, fertilization and application of pe sticides and growth regulators. Our trial was conducted without using of fe rtilizers, herbicides, fungicides, insecticides and growth regulators. Expe rimental station of the Czech University of Agriculture is in Praha-Uhrinev es in fertile beet-growing region (production capacity of soil 84 points) w ith a good reserve of nutrients. Average annual air temperature is 8.3 degr ees C and annual sum of precipitation is 575 mm. Weather pattern in differe nt years is presented in Tab. I. Different weather pattern in different yea rs participated significantly in obtained yields. In 1994 average yield of all varieties amounted to 7.92 t.ha(-1), in 1995 7.51 t.ha(-1) what were ma rkedly higher yields than in the other years. Significantly lowest yield in 1996 was 4.58 t.ha(-1) likewise in 1998. Average yields of tested varietie s in different years are given in Tabs. II to VI. Sets of identical varieti es tested for three, four, five years were compiled for statistical evaluat ion. The varieties Bruta, Samanta and Siria seemed to be the most yielding in these sets. Regarding the good yield, the varieties Astella, Estica and Athlet of new varieties included in the last years in this system of cultiv ation were well manifested. It was proved that for cultivation procedures w ith low inputs or directly for ecological cultivation it is not necessary t o select older varieties or originall regional as it was recommended earlie r. On the contrary, these are mostly very good yielding modern varieties fo rming the yield rather by productivity of spike than the number of spikes a nd high weight of caryopses. They should be also the so-called plastic, i.e . suitable into less favourable conditions, with very good health condition .