POTENTIAL AND ACTUAL PRODUCTIVITY OF COMM ON BUCKWHEAT

For the time being buckwheat belongs to marginal commodities whose tot al area does not exceed 1.4%. Ecological tolerance, quality of achenes and their meaning in diet, proved in prevention to cardiovascular and tumourous diseases, justify renaissance of interest in this, perhaps, somewhat unjustly neglected crop. The study was aimed at evaluating p roduction yield capacities of the Pyra variety, approved in 1991. Exce pt continuous weekly determinations (n = 10 plants in three replicatio ns) of dry matter distribution and leaf area, average number of flower s per cluster and average number of clusters per plant were evaluated. Probable average number of all flowers per plant was determined as a product of number of flowers per cluster and number of clusters per pl ant. The calculation preceded series of methodological testing examina tions about changes in number of leaves per cluster along vertical tra nsection through the stand to prove that we can afford similar general ization. Since it is not practically possible in replication of all pl ants (for demandingness of evaluation) to determine the percentage of long-pistillate and short-pistillate flowers out of all flowers in the plant, the percentage of both of them was determined from average mix ed sample of 1 g weight that flowers from plant were picked altogether , then mixed and weighed. Results were evaluated statistically by regr ession analysis and are summed up in Tabs I to IV and Figs 1 to 3. Cor relation between number of clusters per plant and average daily temper ature of air in the phase of development of buckwheat between 20 to 30 DC (r = 0.82) was confirmed. There is intensive compensation between number of clusters per plant and number of flowers per cluster (Tab. I I). In formative process an important role is played by sufficient amo unt of moisture and air temperature. After defoliating correlation bet ween formation of fruits and average daily temperatures of air is nega tive (r = -0.91) (Fig. 2 and Tab. II). Regarding evaluated three-year period the year 1993 seemed to be optimum as far as the yield is conce rned. Early sown stands set more short-pistillate flowers which are ra ther liable to reduction than long-pistillate flowers with shorter dev elopment. The ratio of flowers of both types is roughly 1 : 1 with sli ght deviations in particular years also with respect to the date and w ay of sowing. In our conditions cultivation of buckwheat seems to be m ore suitable in narrower cereal rows (12.5 cm), regarding lower weed i nfestation. In view of buckwheat in stands established in this way, st and microclimate more favourable to plants is formed, allowing more ec onomic use of soil moisture through the water balance of stand (more a vailable water is retained in soil - even by 6.8%). Proportions of tra nspiration and evaporation components of evapotranspiration of stand a re obviously changing as well. The results presented here may be a cri tical contribution to breeding work or it can serve as agrotechnical r ecommendation, e.g. dressing by nitrogen dose according to actual sett ing of clusters, established on plants is such a way to support the mo st the real yield potential.