The effects of bulb storage temperature, planting date and soil temperature on the growth and development of Narcissus bulb units

Three experiments were set up with field-grown narcissus, starting in 1995, 1996 and 1997. Each crop was grown for two years. Treatments were designed to alter the temperatures to which the bulbs were exposed, and consisted o f twelve combinations of two pre-planting storage temperatures (pre-cooling and no pre-cooling), two planting dates (early and late) and three straw m ulch treatments (no mulch, early mulch and late mulch). Treatments were app lied only in the first year of each experiment, but crops were sampled regu larly over both years and separated into their component parts to measure t he effects of treatments on the growth and development of bulb units. The d ata showed how, over the two-year cycle, changes occurred in the fresh weig ht of the bulb cluster, the daughter bulb unit and the terminal mother bulb unit, which succeeded the daughter bulb unit. The daughter bulb unit follo wed a classic sigmoid growth curve, eventually reaching a weight of up to 1 0 g. The growth and development of bulb components in year one influenced t he number of flowers and bulb yield in year two, but had no effect on the t iming of flowering in year two. Earlier and greater development of the term inal mother bulb unit in year one gave earlier flowering and a greater daug hter bulb unit weight that year. This then resulted in earlier development of the terminal mother bulb unit in year two and more flowers and a greater bulb yield in that year. There were positive correlations between the numb ers of flowers in year two and the weights of foliage, terminal mother bulb unit and bulb cluster at emergence, flower cropping and senescence in year one. There were also positive correlations between bulb yield in year two and the weight of the bulb cluster at emergence, flowering and senescence i n year one. Canonical variate and multi-variate analyses of the bulb compon ent data showed that in year one there were significant effects on plant co mponents of planting date and pre-planting storage temperature, while in th e second year all main effects were significant.