|Abstract or Summary
- The effect of primocane removal and training time on yield components and
cold hardiness of 'Marion' trailing blackberry was studied. In 1991, primocanes
were either not cut, or cut at ground level from plants on a single occasion at
one month intervals from late April to late July. Four canes per plant were
either trained during August, or in February, with all other canes on the plant
removed and measured. July-renovated plants were trained only in February.
Yield components were measured separately on basal, middle, and terminal
sections of each cane.
Cane diameter, main cane length and yield per cane declined linearly
with later primocane removal date. However, yield per plant was highest for
April-renovated plants when yield per cane and total number of canes per plant
was considered. Total branch cane length was highest for unrenovated plants,
which had the highest per-cane productivity. Percent budbreak on main canes
increased with later primocane removal date.
August-trained plants had longer main canes, higher percent budbreak,
and a higher number of fruit per main cane lateral compared to February-trained
plants. August-trained plants yielded 83% more than February-trained
plants, and harvest was significantly advanced in some cases.
The basal section of canes had the highest node number and produced
the largest number of fruit in all removal dates. Percent budbreak declined
from the basal to terminal section of the cane. The longest and most
productive branch canes were produced in basal cane sections, particularly of
Cold hardiness of floricane tissues from the renovated treatments was
evaluated during the winter of 1991/92. Canes from each of the five
primocane removal times were cut on four dates: November 15, December 9,
January 17 and February 7. One-node samples were subjected to controlled
freezing at -6°, -9°, -12°, -15°, and -18°C, plus a 4°C control, in November
and February; in December and January the -6° temperature was replaced
with -21°C. After 7 days at room temperature, an LT₅₀ was developed for
growing point, bud base, phloem and cambial, and pith tissues by estimating
tissue browning on a 1 to 5 scale.
Hardiness of all tissues generally increased from November to January,
then decreased. Differences between sampling dates were generally small,
probably due to a mild winter. Plants renovated in June and July were
significantly hardier than those renovated earlier. Growing point tissues were
the least hardy of those tested. Phloem and cambial tissues were
approximately 4°C hardier than the growing point, while the bud base and
pith were 12°C and 17°C hardier, respectively.
The effect of cane length and site on yield components of 'Marion'
blackberry was studied during 1991 and 1992. During 1991, canes on individual
plants at four sites were cut to either 1.74 m or 2.64 m length. The number of
canes per plant was adjusted to give a total cane length of 10.5 m per plant. In
1992, a 3.50 m length was added, and three sites were studied.
In 1991, separate plants at each site were used for yield component
measures and for yield estimation for each treatment level. Canes from yield
component plants were cut out 1 week prior to the start of harvest. In 1992,
the same plants were used for both yield data and yield component measures.
Yield components varied little along the cane in either year, and there
was no trend in the differences that existed. Site differences were found for
cane diameter, node number, budbreak, number of fruit per lateral, fruit size,
and yield in both years. Correlation analyses could not establish significant
relationships among the variables in either yield component study but much of
the variation in yield components and yield could be due to differences in cane
diameter and percent budbreak, respectively.
It is suggested, based on results of the renovation study and cold
hardiness work, that later renovation dates could form the basis of an alternate
production system using closer spacing in 'Marion' blackberry.