Persistent effects of seedling treatment on growth of sugar beet in pots

Further evidence is provided that the environment of sugar-beet seedlings, or growth substances applied to seedlings, continues to influence growth when the plants are later in other environments. Sugar-beet seeds were germinated at 20 °C in 8, 16 or 24 h photoperiods of constant light intensity, i.e. with different amounts of total radiation. When the seedlings had two leaves (15–18 days old) they were transferred to large pots in the glasshouse. Some seedlings were treated with (2-chloroethyltrimethylammonium chloride) either sprayed on the leaves or applied to the soil, at different times. The treatments affected areas of individual leaves throughout the growing period; plants raised in 24 h photoperiod had the largest leaves, and those in 8 h photoperiod the smallest. Consequently, 24 h plants had most dry matter and 8 h plants least. Plants given most radiation produced leaves fastest and CCC applied early increased the rate, but as the leaves were smaller, except late in 1967, and died sooner, the leaf area duration was less and so yields were less. CCC applied later did not affect leaf production. There was no interaction between amount of radiation and CCC treatment. Twenty-four hour plants had the greatest net assimilation rate (E) early. CCC decreased E early, but increased it later and more when sprayed on the leaves than when applied to the soil. Some factor, possibly pot size, eventually restricted growth and probably diminished the effect of the treatments applied to the seedlings.