The Applications of Different Glycine Betaine Doses on Young Pear Trees Under Drought Stress Conditions

This experiment was conducted at the Fruit Research Institute, MAREM, Eğirdir-Isparta, Turkey, to detect the effects of different glycine betaine doses in drought stress conditions on young pear trees in 2019. The pear trees used in the study were one-year-old Deveci (Pyrus Comminus L.) variety grafted onto OHxF 333 rootstock. There were three different irrigation treatments in the experiment. Treatments were I100 treatment—available soil water reached field capacity for each irrigation, 100% (control); I50 treatment—irrigated with 50% of the water used in the I100 treatment (50% water deficit, moderate stress); I25 treatment—irrigated with 25% of the water used in the I100 treatment (75% water deficit, severe stress). Four different GB doses were used: GB0: 0, control; GB1: 1 mg L−1; GB5: 5 mg L−1; and GB10: 10 mg L−1. GB was not applied to pear trees in the I100 treatment. That is, there were nine different treatments in this study. GB applications provided a 19% increase in Pn of both the I25 and I50 treatments. According to the results of gsw, gsw increased between 18.0% and 27.8% for GB50 and GB25 treatments, respectively. In total, 10.9% and 14.8% increasing rates in shoot length were detected in GB10 applications in both the 50% and 75% water deficit treatments. The highest trunk diameter and fresh root weight results were determined in 10 mg L−1 GB dose applications under 50% water deficit conditions (I50GB10).