Usefulness of selected weather indices to evaluation of yellow lupine yielding possibility

The aim of the undertaken research was an evaluation of the weather condition effect on growth and development as well as the yielding of yellow lupine plants. Weather conditions were characterized on the basis of the amount and distribution of precipitation, Sielianinov's index (K) and climatic water balance index (CWB). Genotypes of yellow lupine: Polo – an indeterminate and Legat – a determinate genotype were included into the research. An experiment was established by using the split-plot–split-block method at four replications on good rye complex soil. It founded on dependencies among values of Sielianinov's index, climatic water balance index (CWB), dynamic of mass increase and physiological indicator of plant growth (RGR). It was found that an unprofitable effect of the precipitation deficit is dependent on the developmental phase of lupine and a genotype. A shortage in precipitation which occurred after sowing caused a prolongation of emergence; however, it did not significantly decrease the plant's density because seedlings were able to use water accumulated in soil during the winter. Whereas, a long period of water shortage in the soil occurred from the beginning of flowering (BBCH 60) to pod setting (BBCH 75) had great effects on morphological features and yellow lupine yield. Unsuitable weather in this period caused a decrease in the plant's height, reduction of leaf area, inhibition of relative growth rate (RGR) and a reduction of pods and seeds number per plant. Polo (an indeterminate genotype), appeared less sensitive on periodic water deficit in the soil than Legat (a determined genotype). This was also confirmed by the values of R index (a ratio of dry mass of root system to the aboveground part mass), which is generally admitted as an indicator of the plant's resistance to drought stress.