บทคัดย่องานวิจัย

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The influence of growing season water stress on the physiology and cold hardiness of 'Redhaven' peach trees (Redhaven peaches)

Gaus, Alvan Glen

Thesis of Ph.D., The Pennsylvania State University, 1990, 157 pages

1990

บทคัดย่อ

THE INFLUENCE OF GROWING SEASON WATER STRESS ON THE PHYSIOLOGY AND COLD HARDINESS OF 'REDHAVEN' PEACH TREES (REDHAVEN PEACHES).

Two postharvest irrigation levels were tested in an Adams County, Pa., peach (Prunus persica (L.) Batsch cv.  Redhaven/Halford) orchard.  In 1987, trickle irrigation levels of 25% and 100% of replacement irrigation based on pan evaporation were initiated following harvest on 5 Aug.  Tents and trenches excluded rainfall and horizontal water movement.  Irrigation level did not influence trunk cross-sectional area (TCSA) increase or leaf relative water content (LRWC).  Only one linear relationship occurred between irrigation level and canopy-to-air-temperature differentials over four dates.  Linear relationships were found between irrigation level and stomatal conductance and transpiration; however, the coefficients of determination were low.  The 25% level resulted in an 11 and 12% reduction in net photosynthesis (Pn) on 2 and 4 Oct., respectively.  No linear relationships between irrigation level and carbohydrates were found.  Only one linear relationship out of six was found between irrigation l

 evel and the -30C Index of Injury (IOI).  Most of the data indicate that a severe water stress did not occur despite irrigation at the 25% level for 60 days.

 In 1988, canopy-to-air-temperature differentials of deficit irrigated peach trees were determined throughout the growing season and developed into either a crop water stress index (CWSI), a cumulative crop water stress index (CCWSI); or a postharvest cumulative crop water stress index (PCCWSI).  No relationships occurred between either CCWSI or PCCWSI and shoot length increase from 1 June to 28 July.  Linear relationships were found between CCWSI (r2 = 0.23), and PCCWSI (r2 = 0.18) and TCSA increase.  Only one relationship out of eight was found between PCCWSI and LRWC.  On several dates, all indices were related to Pn, stomatal conductance, and transpiration; however, the coefficients of determination were less than 0.5.  Relationships between the cumulative indices and carbohydrates were variable.  No relationships occurred between CCWSI or PCCWSI and the -24C IOI, while three out of ten measurements at -30C showed an increase in injury as water stress increased.  The data indicate an inability to produc

 e consistent, uniform relationships between the crop water stress indices and physiological parameters in peach trees.