The Response of Maize to Water Stress: The Effect of Abscisic Acid and Benzylaminopurine.

The young plants of maize, cv. Anjou 245, were cultivated in sand culture under controlled conditions in a greenhouse. The eight-day interruption of irrigation, during which RWC decreased from 87.5 % to 79.7–83.2 %, was manifested in the young maize plants by limitation of growth and production of dry matter in stems and roots. The growth of aboveground part is generally more sensitive to water stress than the root growth. A 100 µM abscisic acid (ABA) solution or a 10 µM solution of benzylaminopurine (BAP) supplied exogenously supported the growth and production of dry matter in roots in the plants exposed to drought, consequently reducing the ratio between stems and roots. The change of ratio between the aboveground part and the roots in favour of the roots is a significant adaptation mechanism of plants to water stress. The plant increases the water intake and limits the water output. This improves its water management mode.

The 8-day interruption of irrigation resulted in decreasing the photosynthesis rate (P_n) and the transpiration rate (E) as compared with plants under no stress. The ABA application induced other decreasing of P_n and E in stressed plants and increased the water use efficiency (WUE). The BAP application increased the P_n and E in the plants exposed to water stress, but the increase of the transpiration rate is disadvantageous during the long-time water deficit.

The decrease of the chlorophyll content in maize leaves under water stress shows that production of dry matter was influenced not only by stomatal but also by non-stomatal limitation of photosynthesis. The negative effect of water stress on the chlorophyll content was mitigated by BAP. 

Supported by the MEYS of the Czech Republic, Project No. 6046070901.