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Productivity of individual cranberry uprights in Washington and British Columbia
Scientia Horticulturae, 20 (1983) 179--184
179
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
PRODUCTIVITY OF INDIVIDUAL CRANBERRY UPRIGHTS IN WASHINGTON AND BRITISH COLUMBIA
G.W. EATON, A.Y. SHAWA and P.A. BOWEN
Department of Plant Science, The University of British Columbia, Vancouver, V6T 2A2 (Canada) (Accepted for publication 13 October 1982)
ABSTRACT
Eaton, G.W., Shawa, A.Y. and Bowen, P.A., 1983. Productivity of individual cranberry uprights in Washington and British Columbia. Scien tia Hortic., 20: 179--184. Yield-component partitioning o f the individual cranberry upright (fruiting shoot) was undertaken using a model which included upright length, number of leaves, flowers, berries and seeds, and fruit weight. Repeat cropping of the upright during the following year was also modelled and tested. Fruit set was a major component of yield, but its action was sometimes indirect. Less important components were the number of seeds per berry, berry enlargement per seed, and upright length. Measures o f antagonism of "fruiting" to floral initiation were obtained which partially explain the biennial bearing habit of uprights. Keywords: cranberry ; Vaccinium macrocarpon; yield ; yield components. INTRODUCTION
Cranberry (Vaccinium macrocarpon L.) yield per unit area has been partitioned into components whose individual contributions were tested (Eaton and MacPherson, 1977; Eaton and Kyte, 1978; Shawa et al., 1981). Important components were upright numbers, the proportion of uprights which flowered, and fruit set. The present paper deals with partitioning yield of individual fruiting uprights into components, including vegetative components not considered before. The proportion of uprights flowering is determined by the ratio of mixed buds to vegetative buds initiated in the previous year. Since cranberries are known to have a biennial cropping habit (Lenhardt and Eaton, 1977; Eaton, 1978), the components of flowering uprights which affect mixed bud production are also dealt with in this paper. MATERIALS AND METHODS
Representative samples of fruiting uprights were taken from commercial bogs in B.C. in 1977. There were 143 'Ben Lear', 58 'Bergman' and 56
0304-4238/83/$03.00
© 1983 Elsevier Science Publishers B.V.
180 'McFarlin' uprights. In Washington, 1732 'McFarlin' fruiting uprights were sampled in 1978. Data measured on each upright included length (M) in mm, number of leaves (L), flowers (F), berries (B), seeds (S), fruit mass (G) in grams and coded presence (2.71828) or absence (1.0) of mixed or plump terminal buds (P). Two perfect models (in that there could be no residual variation) were examined.
M. L/M. F/L. B/F. S/B. G/S = V M. L/M. F/L. B/F. S/B. G/S. P/G = P
(I) (II)
t h e presumed sequence of development is shown by the order of components in each model. Model I partitions variation in fruit yield of flowering uprights. Model II partitions variation in the propensity of uprights to crop again the following year, since they must have a plump terminal mixed bud for this to happen. Components may affect yield directly, or indirectly by influencing later c o m p o n e n t s which in turn affect yield. For instance, fruit set (B/F) may cause a direct variation in yield since more berries might result in a greater yield weight. B/F may also act indirectly by influencing a later c o m p o n e n t such as S/B, which in turn affects yield. Components earlier than B/F might influence yield because they affect B/F. " F o r w a r d " yield c o m p o n e n t analysis (YCA) measures direct and indirect effects of each c o m p o n e n t on yield after all effects of earlier c o m p o n e n t s have been considered. "Backward" YCA measures the direct effect of each c o m p o n e n t on yield including influences o f earlier components which are affecting yield through the c o m p o n e n t measured (Bowen and Eaton, 1983). Additive models were obtained by taking natural logarithms of all terms. Components were then fitted sequentially into multiple regressions and the increment in total R 2 was calculated at each step. In " f o r w a r d " YCA, the sequence is the presumed developmental order. In " b a c k w a r d " YCA, the order is reversed. The increments, expressed as percentages of the total variability, are the coefficients of determination. In addition to expressing yields of G and P in terms of their components, each c o m p o n e n t was expressed in terms of earlier components. RESULTS AND DISCUSSION Yield c o m p o n e n t ratios contribute biological meaning to the models. M and L/M are different aspects of vegetative growth. F/L represents reproductive growth relative to vegetative growth. B/F is the extent of pollination, while S/B is its effectiveness. G/S expresses fruit enlargement relative to seed number and indicates either the effectiveness of seeds in stimulating fruit enlargement, or plant efficiency. The ratio P/G in the model for yield of a terminal mixed bud is simply an error term needed to account for the residual variability in P.
181
In the " f o r w a r d " YCA, B/F was the most important yield c o m p o n e n t of all B.C. cultivars (Tables I--III), and in Washington (Table IV) it was second only to G/S. B/F was much smaller in the " b a c k w a r d " YCA (Table V) than in the " f o r w a r d " , and so the effect of B/F upon yield was partially through actions on later components. Berry enlargement per seed (G/S) made the greatest contribution to yield in the " f o r w a r d " analysis for 'McFarlin' uprights from Washington (Table IV), and was also a large contributor in the " b a c k w a r d " YCA (Table V). G/S was therefore independently responsible for much of the yield variability of these uprights. S/B and F/L made greater contributions to yield in the " b a c k w a r d " YCA than in the " f o r w a r d " YCA in all cases. Therefore, these components directly affected yield, but some of their effect resulted from chronologically earlier components which influenced them. These influences by earlier components were removed in the " f o r w a r d " YCA, and so S/B and F/L contributed less to yield after this procedure. Negative regressions between successive components were common, indicating compensation (Tables I--IV). For instance, fruit set always compensated for flower production. For 'Ben Lear' from B.C. and 'McFarlin' from Washington, components pertaining to reproduction, F/L, B/F and S/B, together accumulated an R 2 which was significant at the 1% level when regressed with P (Tables I and II). The regression coefficients were negative in all cases. Lack of significance for 'Bergman' and 'McFarlin' from B.C. may have been due to insufficient replication. Vegetative growth, represented by M and L/M, accumulated a significant R 2 in all cases except 'McFarlin' from B.C. (Tables I, II and IV). P was always positively correlated with these components. Berry enlargem e n t per seed seemed unrelated to P (Tables I--IV). TABLE
I
Factors a f f e c t i n g y i e l d and f o r m a t i o n of a mixed terminal b u d o n 1 4 3 individual 'Ben Lear' uprights in British Columbia, 1977; logarithms of c o m p o n e n t s regressed o n i n d e p e n d e n t standardised residuals. Figures are coefficients of determination (%) I n d e p e n d e n t variable
L/M F/L B/F S/B G/S G P
M
L/M
1.215.9-** 0.00.7 9.2** 16.7"* 3.6*
31.7-** 4.6* 0.40.2 0.0 0.4
F/L
25.4-** 0.2 1.018.6"* 4.0-*
B/F
0.1 0.738.1"* 4.4-*
S/B
45.1-** 7.1"* 2.1-
G/S
19.5"* 1.4
P/G
Total
64.2**
1.2 47.7 30.0 1.4 56.1 100.0 100.0
M = upright length ( m m ) ; L = leaf n u m b e r ; F = f l o w e r n u m b e r ; B = berry n u m b e r ; S ffi s e e d n u m b e r ; G = berry mass per upright ( g ) ; P = presence ( 2 . 7 1 8 2 8 ) or a b s e n c e ( 1 . 0 ) o f a terminal m i x e d bud. T h e signs are t h o s e o f c o r r e s p o n d i n g regressions.
*P = 5%; **P = 1%.
182 TABLE II Factors affecting yield and formation of a mixed terminal bud on 58 individual 'Bergman' uprights in British Columbia, 1977; logarithms of components regressed on independent standardised residuals. Figures are coefficients of determination (%) Independent variable
L/M F/L B/F S/B G/S G P
M
L/M
37.8-** 7.6-* 0.7 1.3 4.0 10.1"* 8.6*
18.7-** 0.1 1.85.7 0.18.0*
F/L
20.1-** 7.0* 5.08.0* 4.4-*
B/F
0.3 0.963.0** 1.4-
S/B
62.2-** 9.2* 0.0-
G/S
9.7* 0.7
P/G
Total
77.0**
37.8 26.3 21.0 10.3 77.8 100.0 100.0
M = upright length (mm); L = leaf number; F = flower number; B = berry number; S = seed number; G = berry mass per upright (g); P = presence (2.71828) or absence (1.0) of a terminal mixed bud. The signs are those of corresponding regressions. *P = 5%; **P = 1%. TABLE III Factors affecting yield and formation of a mixed terminal bud on 56 individual 'McFarlin' uprights in British Columbia, 1977; logarithms of components regressed on independent standardised residuals. Figures are coefficients of determination (%) Independent variable
L/M F/L B/F S[B G/S G P
M
L/M
78.8-** 16.8-** 2.70.00.8 0.8 1.3
29.8-** 1.71.85.0 0.34.4
F/L
16.4-** 0.3 5.82.3 0.1-
B/F
0.8 2.949.4** 1.1-
S/B
54.7-** 15.0"* 6.9-
G/S
32.3** 0.9
PIG
Total
84.1"*
78.8 46.6 18.1 2.9 69.3 100.0 100.0
M = upright length (mm); L = leaf number; F = flower number; B = berry number; S = seed number; G = berry mass per upright (g); P = presence (2.71828} or absence (1.0) of a terminal mixed bud. The signs are those of corresponding regressions. *P = 5%; **P = 1%.
Most of the variability in P was u n a c c o u n t e d for by the m o r p h o l o g i c a l c o m p o n e n t s i n c l u d e d i n t h e m o d e l . I n a p r e v i o u s s t u d y ( S h a w a e t al., 1 9 8 1 ) , t h e p r o p o r t i o n o f u p r i g h t s f l o w e r i n g (U/Ut) was a n i m p o r t a n t y i e l d - c o m p o n e n t o f s a m p l e d areas. T h i s c o m p o n e n t was p o s i t i v e l y c o r r e l a t e d w i t h F/U, i n d i c a t i n g t h a t s u c h f a c t o r s as t e m p e r a t u r e o r p l a n t n u t r i e n t s t a t u s a f f e c t e d
183
b o t h t h e n u m b e r o f f l o w e r b u d s i n i t i a t e d (U/Ut) a n d t h e n u m b e r o f f l o w e r i n i t i a l s f o r m e d p e r b u d (F/U). R e s u l t s o f t h e p r e s e n t s t u d y s u p p o r t t h e t h e o r y t h a t v a r i a b i l i t y in t h e p r o p e n s i t y f o r u p r i g h t s t o i n i t i a t e f r u i t i n g b u d s is a f f e c t e d b y e i t h e r t h e e n v i r o n m e n t o r s o m e p h y s i o l o g i c a l a s p e c t o f t h e p l a n t . T h i s s t u d y a l s o f o u n d t h a t , in s o m e c a s e s a n d t o a s m a l l e x t e n t , aspects of fruiting deterred fruit bud initiation. This can be explained either by competition for nutrients or inhibition by hormones released from flowers, berries and seeds. TABLE IV Factors affecting yield and formation o f a mixed terminal bud on 1732 individual 'McFarlin' uprights in Washington, 1978; logarithms of components regressed on independent standardised residuals. Figures are coefficients of determination (%)
Independent variable
L/M F/L B/F S/B G/S G P
M
L/M
13.7-** 5.2-** 0.10.8-** 3.8** 4.8** 11.1"*
34.1-** 0.6* 1.4-** 0.9** 0.0 7.5**
F/L
B/F
57.7-** 0.0 0.2 3.4** 0.3 -=*
S/B
0.6-** 2.2** 32.3** 0.0-
G/S
30.6-** 5.9** 4.1-**
53.7** 0.1
P/G
Total
76.9**
37.8 26.3 21.0 10.3 77.8 100.0 100.0
M = upright length (mm); L = leaf number; F = flower number; B = berry number; S = seed number; G = berry mass per upright ( g ) ; P = presence (2.71828) or absence (1.0) of a terminal mixed bud. The signs are those of corresponding regressions. *P = 5%; **P = 1%. TABLE V "Backward" yield component analysis of fruit yield on individual cranberry uprights, coefficients of determination (%) Cultivar
Ben Lear, Bergman, McFarlin, McFarlin,
Independent variable
B.C. B.C. B.C. Wa.
G/S
S/B
B/F
F/L
L/M
M
2.1 3.01.733.7**
32.8** 27.5** 33.4** 40.3**
9.5** 41.7"* 29.9** 4.5**
24.7** 23.1"* 23.4** 7.3**
4.9** 0.1"* 2.81.2"*
26.0** 4.6** 8.7* 13.1"*
G = berry mass per upright (g); 8 = seed number; B = berry number; F = flower number; L = leaf number; M ffi upright length (mm). *P ffi 5%; **P = 1%. The coefficients of determination measured increments in variability at each step. The signs are those of corresponding regressions.
184 Overall, t h o s e c o m p o n e n t s m o s t c o n d u c i v e t o high f r u i t yield w e r e t h o s e w h i c h d e t e r r e d f r u i t b u d f o r m a t i o n . This explains t o s o m e e x t e n t t h e biennial b e a r i n g h a b i t o f c r a n b e r r y . ACKNOWLEDGEMENT Financial s u p p o r t u n d e r O p e r a t i n g G r a n t A 2 0 2 3 f r o m t h e N a t u r a l Science a n d E n g i n e e r i n g R e s e a r c h C o u n c i l o f C a n a d a is g r a t e f u l l y a c k n o w l e d g e d .
REFERENCES Bowen, P.A. and Eaton, G.W., 1983. Yield component analysis of winter damage and flower buds in highbush blueberry. Scientia Hortic., 19: 279--286. Eaton, G.W., 1978. Floral induction and biennial bearing in the cranberry. Fruit Vat. J., 32(3): 58--60. Eaton, G.W. and Kyte, T.R., 1978. Yield component analysis in the cranberry. J. Am. Soc. Hortic. Sci., 103: 578--583. Eaton, G.W. and MacPherson, E.A., 1977. Morphological components of yield in cranberry. Hortic. Res., 17: 73--82. Lenhardt, P.J. and Eaton, G.W., 1977. Cranberry flower bud initiation in British Columbia. Fruit Vat. J., 31(2): 44. Shawa, A.Y., Eaton, G.W. and Bowen, P.A., 1981. Cranberry yield components in Washington and British Columbia. J. Am. Soc. Hortic. Sci., 106: 474--477.
179
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
PRODUCTIVITY OF INDIVIDUAL CRANBERRY UPRIGHTS IN WASHINGTON AND BRITISH COLUMBIA
G.W. EATON, A.Y. SHAWA and P.A. BOWEN
Department of Plant Science, The University of British Columbia, Vancouver, V6T 2A2 (Canada) (Accepted for publication 13 October 1982)
ABSTRACT
Eaton, G.W., Shawa, A.Y. and Bowen, P.A., 1983. Productivity of individual cranberry uprights in Washington and British Columbia. Scien tia Hortic., 20: 179--184. Yield-component partitioning o f the individual cranberry upright (fruiting shoot) was undertaken using a model which included upright length, number of leaves, flowers, berries and seeds, and fruit weight. Repeat cropping of the upright during the following year was also modelled and tested. Fruit set was a major component of yield, but its action was sometimes indirect. Less important components were the number of seeds per berry, berry enlargement per seed, and upright length. Measures o f antagonism of "fruiting" to floral initiation were obtained which partially explain the biennial bearing habit of uprights. Keywords: cranberry ; Vaccinium macrocarpon; yield ; yield components. INTRODUCTION
Cranberry (Vaccinium macrocarpon L.) yield per unit area has been partitioned into components whose individual contributions were tested (Eaton and MacPherson, 1977; Eaton and Kyte, 1978; Shawa et al., 1981). Important components were upright numbers, the proportion of uprights which flowered, and fruit set. The present paper deals with partitioning yield of individual fruiting uprights into components, including vegetative components not considered before. The proportion of uprights flowering is determined by the ratio of mixed buds to vegetative buds initiated in the previous year. Since cranberries are known to have a biennial cropping habit (Lenhardt and Eaton, 1977; Eaton, 1978), the components of flowering uprights which affect mixed bud production are also dealt with in this paper. MATERIALS AND METHODS
Representative samples of fruiting uprights were taken from commercial bogs in B.C. in 1977. There were 143 'Ben Lear', 58 'Bergman' and 56
0304-4238/83/$03.00
© 1983 Elsevier Science Publishers B.V.
180 'McFarlin' uprights. In Washington, 1732 'McFarlin' fruiting uprights were sampled in 1978. Data measured on each upright included length (M) in mm, number of leaves (L), flowers (F), berries (B), seeds (S), fruit mass (G) in grams and coded presence (2.71828) or absence (1.0) of mixed or plump terminal buds (P). Two perfect models (in that there could be no residual variation) were examined.
M. L/M. F/L. B/F. S/B. G/S = V M. L/M. F/L. B/F. S/B. G/S. P/G = P
(I) (II)
t h e presumed sequence of development is shown by the order of components in each model. Model I partitions variation in fruit yield of flowering uprights. Model II partitions variation in the propensity of uprights to crop again the following year, since they must have a plump terminal mixed bud for this to happen. Components may affect yield directly, or indirectly by influencing later c o m p o n e n t s which in turn affect yield. For instance, fruit set (B/F) may cause a direct variation in yield since more berries might result in a greater yield weight. B/F may also act indirectly by influencing a later c o m p o n e n t such as S/B, which in turn affects yield. Components earlier than B/F might influence yield because they affect B/F. " F o r w a r d " yield c o m p o n e n t analysis (YCA) measures direct and indirect effects of each c o m p o n e n t on yield after all effects of earlier c o m p o n e n t s have been considered. "Backward" YCA measures the direct effect of each c o m p o n e n t on yield including influences o f earlier components which are affecting yield through the c o m p o n e n t measured (Bowen and Eaton, 1983). Additive models were obtained by taking natural logarithms of all terms. Components were then fitted sequentially into multiple regressions and the increment in total R 2 was calculated at each step. In " f o r w a r d " YCA, the sequence is the presumed developmental order. In " b a c k w a r d " YCA, the order is reversed. The increments, expressed as percentages of the total variability, are the coefficients of determination. In addition to expressing yields of G and P in terms of their components, each c o m p o n e n t was expressed in terms of earlier components. RESULTS AND DISCUSSION Yield c o m p o n e n t ratios contribute biological meaning to the models. M and L/M are different aspects of vegetative growth. F/L represents reproductive growth relative to vegetative growth. B/F is the extent of pollination, while S/B is its effectiveness. G/S expresses fruit enlargement relative to seed number and indicates either the effectiveness of seeds in stimulating fruit enlargement, or plant efficiency. The ratio P/G in the model for yield of a terminal mixed bud is simply an error term needed to account for the residual variability in P.
181
In the " f o r w a r d " YCA, B/F was the most important yield c o m p o n e n t of all B.C. cultivars (Tables I--III), and in Washington (Table IV) it was second only to G/S. B/F was much smaller in the " b a c k w a r d " YCA (Table V) than in the " f o r w a r d " , and so the effect of B/F upon yield was partially through actions on later components. Berry enlargement per seed (G/S) made the greatest contribution to yield in the " f o r w a r d " analysis for 'McFarlin' uprights from Washington (Table IV), and was also a large contributor in the " b a c k w a r d " YCA (Table V). G/S was therefore independently responsible for much of the yield variability of these uprights. S/B and F/L made greater contributions to yield in the " b a c k w a r d " YCA than in the " f o r w a r d " YCA in all cases. Therefore, these components directly affected yield, but some of their effect resulted from chronologically earlier components which influenced them. These influences by earlier components were removed in the " f o r w a r d " YCA, and so S/B and F/L contributed less to yield after this procedure. Negative regressions between successive components were common, indicating compensation (Tables I--IV). For instance, fruit set always compensated for flower production. For 'Ben Lear' from B.C. and 'McFarlin' from Washington, components pertaining to reproduction, F/L, B/F and S/B, together accumulated an R 2 which was significant at the 1% level when regressed with P (Tables I and II). The regression coefficients were negative in all cases. Lack of significance for 'Bergman' and 'McFarlin' from B.C. may have been due to insufficient replication. Vegetative growth, represented by M and L/M, accumulated a significant R 2 in all cases except 'McFarlin' from B.C. (Tables I, II and IV). P was always positively correlated with these components. Berry enlargem e n t per seed seemed unrelated to P (Tables I--IV). TABLE
I
Factors a f f e c t i n g y i e l d and f o r m a t i o n of a mixed terminal b u d o n 1 4 3 individual 'Ben Lear' uprights in British Columbia, 1977; logarithms of c o m p o n e n t s regressed o n i n d e p e n d e n t standardised residuals. Figures are coefficients of determination (%) I n d e p e n d e n t variable
L/M F/L B/F S/B G/S G P
M
L/M
1.215.9-** 0.00.7 9.2** 16.7"* 3.6*
31.7-** 4.6* 0.40.2 0.0 0.4
F/L
25.4-** 0.2 1.018.6"* 4.0-*
B/F
0.1 0.738.1"* 4.4-*
S/B
45.1-** 7.1"* 2.1-
G/S
19.5"* 1.4
P/G
Total
64.2**
1.2 47.7 30.0 1.4 56.1 100.0 100.0
M = upright length ( m m ) ; L = leaf n u m b e r ; F = f l o w e r n u m b e r ; B = berry n u m b e r ; S ffi s e e d n u m b e r ; G = berry mass per upright ( g ) ; P = presence ( 2 . 7 1 8 2 8 ) or a b s e n c e ( 1 . 0 ) o f a terminal m i x e d bud. T h e signs are t h o s e o f c o r r e s p o n d i n g regressions.
*P = 5%; **P = 1%.
182 TABLE II Factors affecting yield and formation of a mixed terminal bud on 58 individual 'Bergman' uprights in British Columbia, 1977; logarithms of components regressed on independent standardised residuals. Figures are coefficients of determination (%) Independent variable
L/M F/L B/F S/B G/S G P
M
L/M
37.8-** 7.6-* 0.7 1.3 4.0 10.1"* 8.6*
18.7-** 0.1 1.85.7 0.18.0*
F/L
20.1-** 7.0* 5.08.0* 4.4-*
B/F
0.3 0.963.0** 1.4-
S/B
62.2-** 9.2* 0.0-
G/S
9.7* 0.7
P/G
Total
77.0**
37.8 26.3 21.0 10.3 77.8 100.0 100.0
M = upright length (mm); L = leaf number; F = flower number; B = berry number; S = seed number; G = berry mass per upright (g); P = presence (2.71828) or absence (1.0) of a terminal mixed bud. The signs are those of corresponding regressions. *P = 5%; **P = 1%. TABLE III Factors affecting yield and formation of a mixed terminal bud on 56 individual 'McFarlin' uprights in British Columbia, 1977; logarithms of components regressed on independent standardised residuals. Figures are coefficients of determination (%) Independent variable
L/M F/L B/F S[B G/S G P
M
L/M
78.8-** 16.8-** 2.70.00.8 0.8 1.3
29.8-** 1.71.85.0 0.34.4
F/L
16.4-** 0.3 5.82.3 0.1-
B/F
0.8 2.949.4** 1.1-
S/B
54.7-** 15.0"* 6.9-
G/S
32.3** 0.9
PIG
Total
84.1"*
78.8 46.6 18.1 2.9 69.3 100.0 100.0
M = upright length (mm); L = leaf number; F = flower number; B = berry number; S = seed number; G = berry mass per upright (g); P = presence (2.71828} or absence (1.0) of a terminal mixed bud. The signs are those of corresponding regressions. *P = 5%; **P = 1%.
Most of the variability in P was u n a c c o u n t e d for by the m o r p h o l o g i c a l c o m p o n e n t s i n c l u d e d i n t h e m o d e l . I n a p r e v i o u s s t u d y ( S h a w a e t al., 1 9 8 1 ) , t h e p r o p o r t i o n o f u p r i g h t s f l o w e r i n g (U/Ut) was a n i m p o r t a n t y i e l d - c o m p o n e n t o f s a m p l e d areas. T h i s c o m p o n e n t was p o s i t i v e l y c o r r e l a t e d w i t h F/U, i n d i c a t i n g t h a t s u c h f a c t o r s as t e m p e r a t u r e o r p l a n t n u t r i e n t s t a t u s a f f e c t e d
183
b o t h t h e n u m b e r o f f l o w e r b u d s i n i t i a t e d (U/Ut) a n d t h e n u m b e r o f f l o w e r i n i t i a l s f o r m e d p e r b u d (F/U). R e s u l t s o f t h e p r e s e n t s t u d y s u p p o r t t h e t h e o r y t h a t v a r i a b i l i t y in t h e p r o p e n s i t y f o r u p r i g h t s t o i n i t i a t e f r u i t i n g b u d s is a f f e c t e d b y e i t h e r t h e e n v i r o n m e n t o r s o m e p h y s i o l o g i c a l a s p e c t o f t h e p l a n t . T h i s s t u d y a l s o f o u n d t h a t , in s o m e c a s e s a n d t o a s m a l l e x t e n t , aspects of fruiting deterred fruit bud initiation. This can be explained either by competition for nutrients or inhibition by hormones released from flowers, berries and seeds. TABLE IV Factors affecting yield and formation o f a mixed terminal bud on 1732 individual 'McFarlin' uprights in Washington, 1978; logarithms of components regressed on independent standardised residuals. Figures are coefficients of determination (%)
Independent variable
L/M F/L B/F S/B G/S G P
M
L/M
13.7-** 5.2-** 0.10.8-** 3.8** 4.8** 11.1"*
34.1-** 0.6* 1.4-** 0.9** 0.0 7.5**
F/L
B/F
57.7-** 0.0 0.2 3.4** 0.3 -=*
S/B
0.6-** 2.2** 32.3** 0.0-
G/S
30.6-** 5.9** 4.1-**
53.7** 0.1
P/G
Total
76.9**
37.8 26.3 21.0 10.3 77.8 100.0 100.0
M = upright length (mm); L = leaf number; F = flower number; B = berry number; S = seed number; G = berry mass per upright ( g ) ; P = presence (2.71828) or absence (1.0) of a terminal mixed bud. The signs are those of corresponding regressions. *P = 5%; **P = 1%. TABLE V "Backward" yield component analysis of fruit yield on individual cranberry uprights, coefficients of determination (%) Cultivar
Ben Lear, Bergman, McFarlin, McFarlin,
Independent variable
B.C. B.C. B.C. Wa.
G/S
S/B
B/F
F/L
L/M
M
2.1 3.01.733.7**
32.8** 27.5** 33.4** 40.3**
9.5** 41.7"* 29.9** 4.5**
24.7** 23.1"* 23.4** 7.3**
4.9** 0.1"* 2.81.2"*
26.0** 4.6** 8.7* 13.1"*
G = berry mass per upright (g); 8 = seed number; B = berry number; F = flower number; L = leaf number; M ffi upright length (mm). *P ffi 5%; **P = 1%. The coefficients of determination measured increments in variability at each step. The signs are those of corresponding regressions.
184 Overall, t h o s e c o m p o n e n t s m o s t c o n d u c i v e t o high f r u i t yield w e r e t h o s e w h i c h d e t e r r e d f r u i t b u d f o r m a t i o n . This explains t o s o m e e x t e n t t h e biennial b e a r i n g h a b i t o f c r a n b e r r y . ACKNOWLEDGEMENT Financial s u p p o r t u n d e r O p e r a t i n g G r a n t A 2 0 2 3 f r o m t h e N a t u r a l Science a n d E n g i n e e r i n g R e s e a r c h C o u n c i l o f C a n a d a is g r a t e f u l l y a c k n o w l e d g e d .
REFERENCES Bowen, P.A. and Eaton, G.W., 1983. Yield component analysis of winter damage and flower buds in highbush blueberry. Scientia Hortic., 19: 279--286. Eaton, G.W., 1978. Floral induction and biennial bearing in the cranberry. Fruit Vat. J., 32(3): 58--60. Eaton, G.W. and Kyte, T.R., 1978. Yield component analysis in the cranberry. J. Am. Soc. Hortic. Sci., 103: 578--583. Eaton, G.W. and MacPherson, E.A., 1977. Morphological components of yield in cranberry. Hortic. Res., 17: 73--82. Lenhardt, P.J. and Eaton, G.W., 1977. Cranberry flower bud initiation in British Columbia. Fruit Vat. J., 31(2): 44. Shawa, A.Y., Eaton, G.W. and Bowen, P.A., 1981. Cranberry yield components in Washington and British Columbia. J. Am. Soc. Hortic. Sci., 106: 474--477.