Poor crop establishment can be a major constraint to crop establishment in the semi-arid tropics. Simply soaking seed in water overnight before sowing can increase the rate of germination and emergence. This procedure, called 'on-farm seed priming', has also been reported to increase the rate of crop development and increase yields. The overall objective of the work described here is to investigate the physiological basis for these benefits using a mixture of laboratory and field experiments. Germination experiments at constant temperatures in moist conditions showed that seed soaking for 17 h decreased the optimum and ceiling temperatures for germination rate. At temperatures above 30 oC, fewer seeds germinated following soaking. When maize was planted in tubes of moist sand in controlled environments, the effect of soaking on emergence also depended on temperature. With a day temperature of 30 oC, soaking advanced time to 50% emergence by 12 h, but only by 5 h at 35 oC. At 40 oC, soaking delayed time to 50% emergence by 20 h. When grown in favourable conditions in controlled environments or in the field, soaking had little effect on growth or development of maize. There appeared to be no differences in the subsequent growth of primed and un-primed plants that emerged on the same day. However, when soaked and un-soaked seed was planted into progressively drier pots of sand at 35°C, soaking advanced time to 50% emergence by 70 h, Field experiments in Zimbabwe also showed that soaking gave a greater benefit to maize emergence at lower soil moisture contents. The benefits of priming appear to follow from the advantage that priming gives to. the seed in relatively dry seedbeds.

English

0410|AGRIS 0401|AL-Maize Program

Juan Carlos Mendieta

CIMMYT Publications Collection