Effects of pH and calcium salt stress on the seed germination
performance of three herbage species
Abstract
Seed germination is critical for successful crop production, and the
sensitivity to pH and salt stress depends on the plant’s tolerance
mechanisms. In view of the characteristics of calcium-rich and acidic
soils in the karst areas of Guizhou Province, China, the effects of pH
stress and calcium stress on the seed germination characteristics of
three herbages were studied with the goal of exploring and revealing the
mechanism of adaptation of the three herbages to an acidic soil
environment and providing a theoretical basis for the selection and
cultivation of acid-tolerant herbages in southwest China. In this study,
six concentration gradients of CaCl2, including 0, 25 mmol/L, 50 mmol/L,
100 mmol/L, 150 mmol/L, and 200 mmol/L, and seven pH gradients,
including 4.55, 5.35, 6.61, 7.03, 8.0, and 9.18 were established,
respectively. The germination rate, germination potential and
germination index of the seedlings were measured for each seed
germination and seedling growth stage of orchardgrass, perennial
ryegrass, and alfalfa, respectively. The results showed that when the
concentration of salt stress began to change, the herbage seeds could
adapt to salt stress at an appropriate pH condition. When only the pH
value or CaCl2 concentration changes, the increase in pH and CaCl2 will
inhibit the growth of shoots and roots. Weak acid can promote the growth
of shoots and young roots, while alkaline conditions can inhibit their
growth. The effect of a low concentration of CaCl2 was not apparent,
while a high concentration of CaCl2 clearly inhibited the plants. The
optimal pH and CaCl2 of the bud and root lengths changed after the
interaction. In conclusion, there is a substantial difference between pH
and calcium salt stress, and the interaction between pH and calcium salt
concentration has a substantial influence on the salt and alkali
tolerance of the three types of seeds.