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- Author or Editor: Peter J. Porpiglia x
Abstract
Several summer pruning treatments were applied in August to ‘Stayman’/Malling Merton (MM) 111 apple (Malus domestica Borkh.) trees measuring 4m high and 5m wide to examine the resulting changes in light climate. Diffuse photosynthetically active radiation (PAR) increased immediately by about 1/5 on the periphery and 1/10 within the canopy from 2 types of summer pruning. These changes in PAR had no effect on net photosynthetic (Pn) potential, dark respiration (Rd), or specific leaf weight (SLW) determined 21 and 54 days after pruning. One method of summer pruning reduced penetration of PAR into inner canopy positions the year following treatment.
Abstract
Two experimental growth regulators, CGA-15281 (beta-chloroethyl-methyl-bis-benzyloxy-silane) and an analogue, CGA-17856, induced leaf abscission in peach (Prunus persica (L.) Batsch). Responses paralleled temperature following treatment. Older leaves were more responsive than younger ones and abscission occurred prior to leaf senescence. Applications prior to rainfall indicated about 6 hours without wetting was needed for maximum chemical activity. CGA-17856 tended to cause more leaf abscission than CGA-15281.
Abstract
Changes in photosynthetic parameters in ‘Stayman’/Malling Merton (MM) 111 apple (Malus domestica Borkh.) trees measuring 5 m wide and 4 m high were studied for an entire growing season. Parameters investigated included penetration of photosynthetically active radiation (PAR), changes in spur leaf net photosynthetic (Pn) potential, dark respiration (Rd) and specific leaf weight (SLW). As measured by changes in PAR penetration, canopy development was generally complete by mid-May. Pn, Rd, and SLW were modified by canopy position. SLW was influenced by the previous light environment as peripheral canopy leaves had higher SLW’s than interior leaves.