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Changes in the population of germinated seed in a hill pasture during and after a pastoral fallow
Author(s) -
* Nie,
Barker,
Valentiné,
A. D. Mackay,
Hodgson
Publication year - 1999
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1046/j.1365-2494.1999.00160.x
Subject(s) - germination , pasture , agronomy , population , biology , germplasm , sociology , demography
A pastoral fallow, which involves no defoliation of pasture for a period, generally from spring to autumn, is a management tool that can be used either to reduce plant population density through self‐thinning prior to oversowing improved plant germplasm or to encourage natural reseeding in order to increase sward persistence and productivity. Two field experiments were carried out in a hill pasture in New Zealand to quantify the response of the seed population, germinated from soil plugs under glasshouse conditions for over 7 months, to pastoral fallow, as influenced by the timing and duration of the fallow, fertilizer application and aspect, and to identify the germination patterns of different plant species in fallowed and grazed swards. A spring–autumn pastoral fallow increased the germinated seed population of grasses, legumes and weeds by 161%, 51% and 59%, respectively, compared with the grazed control. The variation in germinated seed population during the pastoral fallow showed that seed quantity can be controlled by manipulating the timing and duration of a pastoral fallow. Short duration (2–3 month) pastoral fallows resulted in a significantly lower germinated grass seed population than the full (spring–autumn) fallows. Fertilizer application reduced the germinated grass seed population by 26%. The germinated legume seed population was higher with a shady than a sunny aspect. Regression analysis revealed that the germination patterns of all plant species followed a negative exponential function. Partial differentiation of this function derived a germination rate curve on which a two‐pool (ephemeral pool and base pool) model was developed to describe quantitatively the dynamics of germinable seed reserves in the soil.