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Abstract

Sida hermephrodita or Virginia mallow is a perspective perennial herb in the Malvaceae family able to yield a biomass crop through the last two decades. Additionally, the plants have a lot of uses and benefits for instance it can be used as a fodder crop, honey crop, ornamental plant in public gardens. It has favourable features for example fast growing and resistance against the disease and climatic fluctuations, etc. Since Sida is in the beginning phase of domestication, it has a serious disadvantage: the low and slow germination as a big part of wild plants. Due to the expressly low germination percent, the need of seed showing of driller should tenfold 200 thousand seeds/acre instead of 10–20 thousand, which is not available and expensive. Therefore the practical purpose of our research of seed physiology was to increase the seed germination percent in the available, basically wild Sida population. In the first stage of our experiments we examined two factors relating to seed germination percent and seed germination power during our research: the influence of hot water treatment and the effect of exogenous or endogenous infection of seeds. However, in our germination tests, utilizing the scarified seeds with hot water (65, 80 and 95 °C), from 29.3% to 46% germinated from those samples, which were collected from the population of S. hermaphrodita in Debrecen. The average germination for all season was 5–10% without treatment and rinsed using hot water up to almost 50%. When applying physically scarified use, the oldest seeds showed the best germination (46%) after the hot water operation in spite of the previous studies. We discovered that there is a close relationship between the collecting time of the seeds and the ration of seed infections, as well as germination percentage. Thus, the 2009 season was the most favourable in case of contamination (control: 17.3% and 80 °C treatment: 0%) as well as germination percent. It could be concluded that the best season for our findings was 2009 due to autumn harvest of Sida seeds. In our opinion, the autumn harvesting should be the best time to overcome the problem of the low germination and high infection percentage. We also discovered that apparently there is a close relationship between the seed fresh weight or water uptake capability and the percentage of infection. Following these recognitions, we modified our technique in such a way that we fractionated the seeds based on their fresh weight / or relative density before we carried out the treatment. When we filtered the floating seeds on the surface of water, the hot water treatment was performed considerably better on the sunk seeds after separation. Therefore by this special priming process, we were able to reach 80% germination capacity of Virgina mallow seeds under laboratory conditions (26 °C without illumination).

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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 b 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.

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The world’s energy consumption continues to increase, which results in demographic changes, living standard increases and technical development. In the world and Hungary the interest in biomass crops also has increased considerably over the previous decades. This paper summarizes the most important biological, biotechnological and agronomical researches and results of our working group, in Department of Agricultural Botany, Plant Physiology and Plant Biotechnology, University of Debrecen. It represents our research group publications and introduces some efficient propagation possibilities of promising new perennial bioenergy crops, giant reed (Arundo donax L.) and Virginia fanpetals (Sida hermaphrodita Rushby).

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