Jojoba flower buds: temperature and photoperiod effects in breaking dormancy

Abstract

Jojoba (Simmondsia chinensis [Link] Schneid.) is a long-lived desert shrub, valued for the liquid wax which makes up 50% of the seed weight. As attempts are being made to domesticate the species, it is important to understand the environmental factors controlling the reproductive cycle and governing seed yield. The effects of temperature and photoperiod in breaking flower bud dormancy were studied on plants growing under well-watered conditions in controlled environments. Plants 42-48 months old produced only dormant flower buds when growing in 27/22¦ to 36/31¦C day/night temperature. When the plants were moved to lower temperatures of 24/19¦ or 18/13¦, every plant produced a flowering flush. In two experiments, clonal material was grown at either 30/25¦ or 36/3l¦C, then moved to lower temperature treatments. Down to the lowest temperature used (18/13¦), the greater the drop in temperature, the greater the number of flowers which opened. Flowering occurred under both short (8 h) or long (16 h) photoperiods. There was a critical temperature in the region of 27/22¦ to 30/25¦, above which no flowering occurred. Flowering was not dependent on a large diurnal temperature range, but occurred only if the plants were subjected to a low temperature for at least 21 days.