The influence of reduced temperatures after emergence on the subsequent growth and development of the potato

Summary The performance of potato platato plants raised under glass and transplanted to the field after emergence was compared with that of field-raised plants. The transfer from the warmer environment of the glasshouse to the cooler environment of the field resulted in immediate initiation of tubers. The period between initiation and the commencement of rapid bulking was, however, prolonged so that some of the advantage was lost. Nevertheless, this technique enabled yields, in the range of 2–6 tons per acre to be achieved some 4–5 days carlier; the tubers were also more uniform in size. Foliar applications of urea after tuber initiation hastened and extended the phase of rapid bulking, leading to carlier marketable yields and to higher yields at maturity. Urea applied before tuber initiation delayed its commencement. Plants which were transplanted after raising under glass always matured more quickly and gave lower final yields than field-raised plants. The physiological bases of the respones found are discussed. Some plants were exposed to frosts. Recovery from frost damage was rapid; the rate of tuber bulking was slower but yields at maturity were slightly higher than those of plants protected from forst.