Effect of Pot Size and Timing of Plant Growth Regulator Treatments on Growth and Tuber Yield in Greenhouse-Grown Norland and Russet Burbank Potatoes

Abstract

The effects of pot size, timing of the application of paclobutrazol (PTZ) and gibberellic acid (GA 3 ), and the counteractive effect of these two compounds on growth and tuber yield of greenhouse-grown Norland and Russet Burbank potatoes were investigated. Plants were grown either in 1.5-liter pots (15 cm deep) or 3.0-liter pots (18 cm deep) and received a foliar application of either 1.5 mM PTZ or 9 × 10 −3 mM GA 3 at early or late stolon initiation. Some plants that had been foliar treated with 1.5 mM PTZ at early stolon initiation were foliar treated with 9 × 10 −3 mM GA 3 at late stolon initiation. PTZ reduced haulm length in both cultivars significantly, particularly when the treatment was applied at early stolon initiation, but the late treatment reduced haulm length only when growing in 3.0-liter pots. Irrespective of the timing of treatment, GA 3 increased haulm length in Norland growing in both pot sizes, but the treatment increased haulm length in Russet Burbank only when applied at late stolon initiation. GA 3 applied after PTZ did not overcome the growth-inhibiting effect of the PTZ treatment. The PTZ treatment effectively increased usable tuber number/plant (UTN) in Norland, but PTZ had no effect on UTN in Russet Burbank. PTZ reduced usable tuber weight/plant (UTW) only in Norland growing in 1.5-liter pots. By contrast, GA 3 increased UTN only when treated at late stolon initiation of 1.5-liter potgrown Norland, whereas the same treatment was effective when applied only at early stolon initiation for Russet Burbank. For Norland, the increase in UTN by early applied PTZ was reduced by the subsequent application of GA 3 . The use of 3.0-liter pots for minituber production in both Norland and Russet Burbank appears to have no advantage over growing in 1.5-liter pots, particularly when PTZ or GA 3 is used to enhance tuberization.

Effects of plant growth regulators on growth and yield of pre-basic seed potato production under glasshouse condition

“…Paclobutrazol produced the maximum number of heavier and larger minituber than other PGRs (Table 2&4). The results of the present investigation are in agreement with the results of Kianmehr et al (2012) and Bandara et al (1998). Paclobutrazol is a triazole compound which inhibits extension growth in many plant species and blocks GA biosynthesis in plants (Davis et al, 1988).…”

Development of the banana plants 'Prata Anã' and 'FHIA-01' under the effect of paclobutrazol applied on the soil

“…This result indicates that PBZ inhibiting effect was lower when the plants had a higher height at the moment of application, what could have been explained by an effect of dilution in the total mass of the plant or by some problem associated to the sites of action of the product (less activity and/or less sensitivity). The results found agree with those obtained by (Bandara et al 1998), who, evaluating the effect of time of PBZ application on vase-cultivated potatoes, observed that the effect of PBZ applied at the initial stages was higher than when applied at advanced culture stages.…”

“…Thus, the use of growth regulators to reduce plant height may be a solution for plants cultivated under protected environment, as shown by some promising studies on banana plant growth regulation (El Otmani et al 1992, Jeyakumar et al 2003. Among the main growth regulators used in agriculture the most prominent is paclobutrazol (Khurshid et al 1997, Yim et al 1997, Bandara et al 1998, Rademacher 2000 EMANUEL MAIA et al Mouco and Albuquerque 2005). The main plant responses observed after paclobutrazol application are: smaller length of the new shoots, green color intensification, increased chlorophyll concentration and reduced foliar area (Khurshid et al 1997, Yim et al 1997, Carvalho et al 2005, Mouco and Albuquerque 2005.…”

The effect of the time and mode of application of gibberellic acid on the growth and yield of potato plants derived from true potato seed

“…8,9 However, in the case of plants from TPS the effect of GA 3 varied with the method and time of application (Table 1). Thus single applications of GA 3 in the spring caused an increase in plant height irrespective of the stage of plant growth at the time of treatment.…”

“…8 In contrast, a single application of exogenous GA 3 increased not only plant height but also tuberisation. 9 Since the levels of endogenous gibberellins vary during plant development, 10 it is likely that the effect of single applications will also vary with time.…”