In a three-year model experiment the water deficiency resistance and the quality of yield were investigated in the case of soybean and bean cultivars of determined growth. The plants were grown under irrigated and non-irrigated conditions, modelling the conditions of drought. The soybean cultivars used a considerably higher amount of water before reaching the green pod maturity stage than the bean cultivars. Their water use under water stress decreased considerably (46%), in contrast with beans, where this decrease was only 18–21%. This correlates with the vegetation period of the varieties, their water use in certain vegetation periods and the development of their roots. The roots of beans determine the size of the yield and that of water circulation but only affects the formation of pods in a few varieties. The roots of soybean cultivars affect the size of yield and the quality of seeds as well. This is especially important in organic matter circulation under water-deficient conditions. If the roots are small, the dry matter and oil contents increase more intensively in the seed, but this has no effect on the protein content of the seeds. The small root mass and small specific leaf area (SLA) of the early soybean cultivar McCall and the Hungold variety of beans decreased yield losses under water deficiency conditions, in contrast with the mid-late maturing soybean variety Evans, where this was not experienced.
investigations were made on the relationship between plant density and plant height, and on the yield, thousand seed mass, and ratio of diseased and broken seeds of varieties with different seed sizes. Experiments were carried out to analyse the effects of potassium on the yield, bacterial diseases and nutritive quality of the seed of bean varieties. Three dry bean cultivars representing the small, medium and large seed size groups were investigated. Six plant density treatments were chosen based on theoretical seed norms, taking the germinative value of the seeds into consideration. The correlation between plant density and yield average showed that the volume of yield increased for varieties with large and medium-sized seeds up to a plant density of 285-400 thousand/ha, after which it declined. On the basis of the results, yield averages at plant densities of 285-334 thousand plants/ha were 0.17 t/ha higher than those achieved at low density (200 thousand plants/ha). At greater plant density the plant height increased in the case of large-seeded varieties and there was a considerable decrease in the thousand seed mass. With an adequate water supply a high level of potassium decreased the number of pods and seeds per plant compared with the basic level, which gave a yield of 2.5 t/ha. The use of high rates of potassium fertilizer decreased the number of infected seeds, but the differences were only significant for the small-seeded variety. A moderately high potassium level was advantageous for food quality, particularly during drought.
The appearance of Fusarium species and the micronutrient content of pea varieties were investigated in different plant development periods. Field experiments were carried out for three years on six dry pea varieties grown without irrigation on a soil infected with Fusarium species. Green and dry plants divided into shoots (including stems and leaves), pods and seeds were used to determine the presence of Fusarium species and the concentration of micro- and macroelements. In the green shoots and seeds of varieties registered as susceptible to Fusarium oxysporum, other species such as F. solani and F. culmorum were also detected. F. oxysporum and F. solani were found in the dry seeds not only in varieties susceptible to F. oxysporum but in resistant ones as well. In the case of susceptible varieties the phosphorus and nickel contents in the flowering plants decreased significantly compared to those in varieties registered as resistant to F. oxysporum. In later stages of plant development the K and Mo contents increased significantly in the green shoots and the accumulation of Mn and Mo in the green seeds intensified. The very low B concentration in the dry pods contributed to the internal infection of dry seeds by decreasing the stability of the cell wall. In the dry seeds of varieties susceptible to F. oxysporum a considerable decrease in the S content was found parallel with marked increases in the Mo and Mn contents. The sugar content of green seeds decreased significantly in peas susceptible to F. oxysporum, but neither the protein, nor the starch or sugar contents of the dry seeds decreased in comparison to the resistant ones.
The drought tolerance of six green-and yellow-podded varieties of green beans with different genetic backgrounds was tested in the phytotron. During the week prior to flowering the plants were kept either at 25/15°C (day/night) or at high temperature (30/15°C), with RH 75% and optimum water supplies. The heat-stressed plants were then divided into three groups; the first was returned to the control (25/15°C) chamber (RH 75%, optimum water supplies), while the second and third were exposed to mild drought stress (RH 60%, 50% water) at temperatures of 30/15°C and 35/25°C, respectively, throughout the flowering period.The varieties survived the short period of heat stress (30/15°C) prior to flowering without damage provided the temperature during flowering was reduced to 25/15°C and the water supplies were optimum. There was a sharp increase in the carotene level in the leaves of drought-stressed plants when the temperature during flowering was 30/15°C, but in plants exposed to 35/25°C during flowering the level dropped to near the control level. The latter group exhibited considerable damage, with a reduction in the water-soluble antioxidant content (ACW: antioxidant capacity of water-soluble substances) and the chlorophyll
content compared with the control.The antioxidant content (ACW) in the dark green leaves of green-podded varieties was lower than in the yellow-podded varieties and did not change as the result of drought and heat stress. In yellow-podded varieties, however, there was a significant decline in ACW in response to stress. Differences between the varieties in their adaptability to drought and heat could be detected as changes in the chlorophyll and carotene contents of the leaves even at 30/15°C.