Growth, radicle and root hair development ofDeschampsia flexuosa (L.) Trin. seedlings in relation to soil acidity

Abstract

Deschampsiaflexuosa (L.) Trin. is an abundant grass species in the ground flora of acidic beech forests in southern Sweden. Generally, the species is restricted to a limited soil pH range (pH 4-5). The main objective was to study the influence of different soil acidities on germination, initial root development and on the growth of the species. The experiments were carried out under controlled conditions and designed to simulate the physico-chemical conditions present in the field. By using forest soils within the pH range 4.0 to 8.3 and artificial variation in pH (3.2 to 7.6) of soil-water extracts, it was possible to evaluate the influence of soil reaction and the H + per se.In all experiments seeds have been used. Germination was significantly delayed in the very acid soil (pH 4.0) in comparison to the germination in soils within the pH range (4.4 to 6.4). Soil substances, other than the H +, might be responsible for this delay in germination, whereas development of the radicle was markedly affected by increasing H + concentrations. Especially the development of root hairs was sensitive to H + and was significantly reduced at a pH<3.8. By increasing soil acidity the injury symptoms, including curling and discolouring, became more intense and at the highest acidity (pH 3.2) the radicles appeared brown, stunted and the root hairs were lacking. Most favourable growth was obtained at pH 4.4 and 5.0. Soil pH levels above and below this range limited both shoot and root growth. The results showed very good correspondence with observations made in Beech forest soils in southern Sweden, where the species was growing in soils within the pH range 3.9 to 5.1 with a peak growth at pH 4.3. This study shows that in soils at pH<3.8, the poor development of the radicle may be crucial in the establishment of Deschampsia flexuosa. Root hair development was more sensitive to soil acidity than radicle elongation. Germination was delayed in very acid Beech forest soils but other factors than the H-ion per se may be responsible for this delay.

The Nutrient Status of Some Graminaceous Species in Britain. 2.Deschampsia Flexuosa(L.) Trin

“…Dickinson (1 984) concluded that nutrient availability in grassland soils is largely dependent upon the rate of decomposition of organic residues in the soil or litter layer. Differing supplies of calcium, iron, manganese and potassium had only insignificant effects on growth, whilst Balsbergpahlsson (1995) also reported that concentrations of copper, zinc and iron did not reach toxic levels in the extremely acid soil.…”

Capacidade de absorção de nutrientes do capim-mMarandu (Brachiaria brizantha) e da planta daninha malva (Urena lobata) em função do pH

“…Tabela 1 -Equações de regressão polinomial para os diferentes fatores analisados, em função do pH da solução nutritiva Em solos ácidos, os altos níveis de alumínio ou manganês e a deficiência de cálcio são, freqüentemente, considerados os principais fatores limitantes do crescimento das plantas (Balsberg-Pahlson, 1995;Kuhn et al, 1995;Van Raij, 1989), embora a toxidez de ferro possa, também, ser considerada (Sanchez & Salinas, 1982). Neste trabalho, os efeitos deletérios do alumínio podem ser desconsiderados, visto que a solução nutritiva utilizada não apresentava este elemento na sua composição.…”

Effects of wood ash, green residues and N-free fertiliser on naturally regenerated birch and field vegetation in a young Norway spruce stand in SW Sweden

“…However, the ability to assimilate nitrate is also present in birch, heather and spruce (Friemann et al 1992;Troelstra et al 1995;Heiskanen 2005). Another mechanism to consider as regards possible reasons for the positive effects of the Ash and Vitality treatments on D. flexuosa is that seedling establishment in acid humus (<pH 4) is enhanced even by a small increase in soil pH (Balsberg-Påhlsson 1995). Wood ash did not affect humus pH at the study site (Table 4), but the ash might have created favourable conditions in terms of pH on top of the humus.…”