Factors affecting the performance of varieties released recently in the South Africa sugar industry

Abstract

There are several areas in the South African sugar industry where the ubiquitous variety, NCo 376, is being superseded by newer varieties. Growers have a choice of varieties which have outyielded NCo 376 in trials under a wide range of conditions. There are others which have yielded more than NCo 376 in certain conditions. It is opportune to report the results of trials that have been conducted to investigate the agronomic char­ acteristics of the recently released varieties. The main factors which influence the yield of one variety relative to another are fluctuations in soil moisture, season and age at which the cane is harvested, soil type, pests and diseases. Some of these factors have been deliberately varied in variety trials while the effects of others have been deduced by comparing the results of dif- ferent trials. .

Full text

Proceedings
of
TheSouthAfricanSugar
Technologists'
Association
-June 1985
FACTORS
AFFECTING
THE
PERFORMANCE
OF
VARIETIES
RELEASED
RECENTLY
IN
THE
SOUTH
AFRICAN
SUGAR
INDUSTRY
By
N. G.
INMAN-BAMBER
SA Sugar Association Experiment Station, Mount Edgecombe 4300
5
Abstract
There are several areas in the South African sugar industry
wherethe ubiquitous variety, NCo 376,is beingsuperseded by
newervarieties. Growers have a choiceof varietieswhich have
outyielded NCo 376 in trials under a wide range of conditions.
There are others which have yielded more than NCo 376 in
certain conditions. It is opportune to report the results of trials
that have been conducted to investigate the agronomic char-
acteristics of the recently released varieties. The main factors
which
influence the yield of one variety relative to another are
fluctuations in soil moisture, season and age at which the cane
is
harvested,soil type, pestsand diseases. Some of these factors
have been deliberately varied in variety trials while the
effects
of others have been deduced by comparing the results of dif-
ferent
trials. . Introduction
The amount of variety NCo 376 crushed annually has de-
clined gradually since
1982
and the combined amount of
NCo
376,
NCo 310, NCo 293 and N55/805 crushed annually
hasdecreased from 88,2to
82,7%
of the total crop (Lamussev").
The area allocated to new varieties in co-operative nursery
schemes provides a better indication of the changes occurring
in the industry. The predominant varieties in the Lowveld
Nursery Scheme in the Eastern Transvaal are N14and 159/3,
which
occupy 67 and
18
ha respectively while NCo 376 oc-
cupies 3 hectares (Rowland"). In the district controlled by the
Natal Estates
Local
Pest and Disease Control Committee, 52
and
22%
of the total area planted in the spring of 1984 was
allocatedto N12and NII respectively. NCo 293 and NCo 376
were
plantedon only
13
and 6%ofthis area respectively
(Mann").
Methods
Replicated
field
trials with commercial sugarcane varieties
have been established in a number of regions in South Africa
and Swaziland since
1966.
The rate of releaseof new varieties
increased after
1977
and the agronomy evaluation programme
became linked to the selection and release programme. A new
seriesof trials was established whenever two or more new va-
rietiesreachedthe bulking-up
stage.
The sites for the new series
of trials were located at Pongola, on the Mtunzini propagation
farm. on the Ottawa and Hillhead sectionsof Natal Estates, on
the Paddock section of CG Smith
Sugar,
Umzimkulu, and at
1aagbaan.Newvarietieswerealso evaluated in trials at Nyalazi,
Umfolozi and Shakaskraal. For convenience, all sites were
grouped into the following regions:
Region
Code Experimental site
[ northern irrigated NIRR
Komatipoort,
Mhlurne, Big Bend.
Northern Makatini
northern rainfed NDRY Nyalazi, Umfolozi
[ coastal dolerite DOLR Mtunzini
(SASA
farm &Lawrieson
Coastal Estate)
coastal shale SHAL Shakaskraal, Flanders. Ottawa
[ coastal red sands REDS Beach Bush Estate (Urnhlanga)
Sands coastal grey sands GREY Empangeni,Tongaat, Hillhead Estate
[ hinterland HINT Melrnoth, Paddock
Upland rnistbelt MIST Mowbray (Greytown). Jaagbaan
The total numbers of yield results obtained in each
region
for each variety are shown in Table I. Eachresult wasthe mean
of between two and six (usually three) replications. Several
trials were designed to determine the
effect
of management
factors on the performance of varieties. The mean yield of a
variety at a particular
level
of one of these factors,eg fertilizer
level.
was considered as one result. For each yield result there
were between one and six results for quality of the stalk and
up to
18
results for height and population of stalks. The height
of stalks was measured using the mean height of the top visible
dewlap on any 20 stalks in a plot. NCo 376 was used in all
trials and most results were expressed relative to the result of
NCo 376 sothat varieties that occurred indifferenttrials,could
be compared. The term 'relative' usually refersto the result of
a variety divided by that of NCo 376 and multiplied by 100
to convert it to a percentage. In the case of sucrose content,
'relative' refers to the value for NCo376 subtracted from that
of the relevant variety.
TABLE I
Number of crops (plant or ratoon) from which yield results were obtained in
different regions
Variety
Regions NCo J59/ NCo NCo N52/ N55/ NI6
376 3193 310 119 805 N7 N8
NIl
Nil
NI3 NI4
NIRR 173 85
II
50 126 65 22 -20 -624 6
NDRY 9I--I9-8I-8I-
DOLR 38 10 -18 10 22 22 18 18 8 6 8 8
SHAL 27 17 -10 19 15 17 -15 8 6 6 6
REDS 24 ----24 -24 - - ---
GREY 36 6 - - 6 36 -36 11 7 10 33
HINT 50 6
41
-19 47 10 -12 9 6 3 3
MIST 20 3 17 -7 14 2 -10 5722
Results and discussion
A general comparison between a number of commercial va-
rietiesand NCo 376 was made by regressing their sucroseyields
per annum on the annual yield of NCo 376 obtained from the
same treatment in the same trial (Figure I). The useof the yield
of NCo 376 as a measure of the environment wasjustified only
becauseat the time, this variety comprised more than
70%
of
the sugarcane crop in Southern Africa. The mean yield of all
varieties in a trial is an acceptable measure of the environment
in this kind of analysis (Eberhart and
Russell
'), but was con-
sidered to be less meaningful than the yield of the standard
variety. The number of varieties in a trial seldom exceeded
seven and some entries were failures so that data concerning
them would have obscured environmental
effects.
The high correlation coefficients (r)of N7 and N 14indicated
that these varieties weredependable in that their performances
could be
gauged
reliablyfrom a knowledge of the performance
of NCo 376 in a particular situation. The correlation
coeffi-
cients of N
12,
N16and 159/3 were
lower,
indicatingthat these
varieties were adapted to a slightly different set of environ-
mental conditions than those to which NCo 376 wasadapted.
The relatively low correlation coefficients
of
N55/805,
NCo 293, NCo 310,
N521219,
NIl
and NI3 indicated thatthey

6
Proceedings
of The
South
African
Sugar
Technologists'
Association
-June
1985
nrbnrbN14
N55/805 231 0,90 0,86 J59/3 125 0,94 0,96
9NCo293 69 0,90 0,87 16 NCo310 79 0,92 0,94 NCo 376
N7 74 0,97 0,87 N52/219 185 0,91 0,86
N11 88 0,91 0,83 N14 47 0,98 1,06 " J59/3
/
N12 41 0,94 0,86 ," NCo310
815 ,
N13 48 0,90 0,93 ,/.
,
,.
N16 27 0,95 1,02 '/
,.
~
,// N52/219
,"
ro ,//
714 ,
~
,./
'/
I".
ro
"/
/
s: ,.
~
,",/
/
613 ///
:Q
'.
.!!!
///
>NCo293
,"
/
*=
"./
CIl N55/805 '/
II>
0512
//
/
'-
,.
u,//
::J ,.
(J)
//
/
'.
//
/
411 . '/
,.
'//
".
,//
',
,"/
"'
34567 8 9 10 11 12 13 14 15 16
Growth
conditions
Growth
conditions
Poor
~
Moderate Good •
Excellent
Sucrose
yield
of
NCo 376 (t
ha-
1a-1)
FIGURE 1 Annual sucrose yield of sugarcane varieties regressed against annual sucrose yield of NCo 376 under the same conditions. Growing
conditions of (a) poor to moderate and (b) moderate to good (irrigation). n =number of observations, r=correlation coefficient, b=
regression coefficient.
were
fairly
specific
in their
growth
requirements or that they
were
fairly
unpredictable. Some of the
specific
requirements of
these and other varieties
will
be evident in further discussion.
Other authors have used the
regression
coefficient
together
with the correlation
coefficient
as a measure of the stabilityor
adaptability of a variety (Eberhart and Russell', Galvanez-,
Ruschel"), In this investigation it wasa measureof adaptability
onlyin that NCo
376
was
regarded
asa
highly
adaptable
variety.
The
regression
coefficient
(b) was used not as a measure of
adaptability so much as to identify varietiesthat could exploit
a
highly
favourable environment and those
which
were rela-
tively resistant to an adverse environment. The 'b' values of
N14 and N16
were
greater than one and they therefore ap-
peared to be
highly
responsive to favourable
growing
condi-
tions.J59/3,NCo 310and N13appearedto be
fairly
responsive
to favourable conditions, but the other varieties appeared to
be relatively unresponsive. N12, NCo 293 and
N55/805
were
relatively resistant to adverse
growing
conditions.
Ratooningability or persistence refersto the abilityof a su-
garcane variety to sustain production over many ratoons and
is not necessarily associated with the rate at
which
the ratoon
develops after the previous crop has been cut. The
effects
of
management, soil and climaticfactors on persistence are prob-
ably more important than
genetic
factors.
Nevertheless, ex-
perience gainedfrom
growing
thesevarietiescommercially has
been confirmed by trial results. Consistent
changes
in relative
cane yield over three or more ratoon crops are given as
coef-
ficients
ofregression of relative caneyield upon ratoon number
in Table 2. Yieldsof plant cropstend to be misleading at times
and wereexcluded from the analysis of ratoon results. A zero
isgiven
where
no trend was evident.
Changes
accompanied by
similar
changes
in relative stalk population
were
noteworthy.
Relative cane
yields
of J59/3,
N521219
and
NIl
tended to
decrease more rapidlyand in more
regions
than those of other
varieties.
However,
there waslittle
change
in the relativeyield
of these varieties in the northern irrigated
region
during the
first
fourratoon
crops.
Poorratooningin N
55/805
inthecoastal
hinterland and mistbelt was probably due to its susceptibility
to rust,
which
was prevalent. In
general,
the relative yield of
N8 decreased with number of ratoons.
However,
the yield of
this variety
was
greaterthan that of NCo 376in the
grey
sands,
even in later ratoon
crops.
The ratooning qualitiesof N12ap-
peared to be as good as those of NCo 376 in all conditions
except
on the
grey
sands. In these
soils,
its superiority may not
have lastedfor morethan fourratoons.N13alsoratooned
well,
except in the mistbelt to
which
it may not be
well
adapted.
Yields
of N14and N16in later ratoons are not yet available
butNI4
has consistently outyielded NCo 376 in three ratoon
crops at
Pongola.
TABLE 2
Relative
sucroseyield(5), changein relativecaneyieldper crop
(6)
overa given
range (R) of ratoon crops in different regions. An asterisk indicates a similar
change in relative stalk population.
Variety
Region
J59/ NCo NCoN52/ N55/
3 293 310 219 805 N7 N8
NIl
NI2 N13 N14 NI6
NorthernS
96 94
94 88
90 90
9/ /04
irrigated6-10 -I 0-7
-I
-I -4 0
R 5-7
I-II
1-12 4-7 1-12 1-6 4-7 1-3
NorthernS
90
94 98 87 /04 /02 97
dry 6
Coastal S 84
90
84 86 95 85 90 I/O 99
124
107
dolerite 6-6 +3 -9 -7 0-3* -8 0 0
R 1-4 1-4 2-4 1-4 1-4 1-4 1-4 1-4 2-4

Proceedings
of The
South
African
Sugar
Technologists'
Association
-June
1985
7
FIGURE 2 Effect of harvest season on the sucrose yield of some va-
rieties in certain regions relative to the sucrose yield of
NCo376 under the same conditions. An asterisk denotes
astatistically significant difference from NCo 376.
Coastal
Sands
~
Coastal&
lUpland
0------0
N8
• • N12
~·
....
·
......
xN13
0------0
NCo 293 Upland
....
.--
...... N7
\\\\\
,0---1::\
"fJ'" \
b
....
P
....
"
"0
..
"
-,
0---0
,
,
,0..
"
:",
,'o---o--.o------d
,
,
,
,
I
,
,
,
,
I
o
0-----0
J59/3
• • NCo 310
0------0
N52/219
• • N14
A
2,0
1,6
1,2
~
0,8
ro
(.J
~
~
0,4
M
o
U
Z 0
....
0
...
C
Ql
E
-04
o '
(.J
Ql 1,2 B
<II
0
....
(.J
::l
<II
0,8
>
...
Ql
'c
ro 0,4
>
....
0
...
C
Ql
...
0
c
0
(.J
Ql
<II
0
g-0,4
CJ)
-0,8
-1,2
-1,6
F
MAMJ
J
ASONDJ
Month
of
year
FIGURE 3 Differences between some varieties and NCo
376
in su-
crose content grouped according to month of sampling (a)
northern region, (b) southern regions.
In some varieties, the
effect
of season was evident in their
relative sucrosecontents but not in their relativesucroseyields
(Figure
3).
In the northern irrigated region, relative
sucrose
contents of NCo 310 and NI4 were best when harvested in
spring and J59/3 and N
521219
were more suited to being har-
vested inautumn. In the mistbeltand coastalhinterland
region,
the sucrosecontent of NCo 293exceededthat of NCo 376only
in spring. Harvestingin spring wasfavourablefor N7 and N13
in coastal doleriteand shale soilsand for N8 in coastal sands.
In all the southern areas, harvestingin autumn and winter was
*
N12 N13
COASTAL &UPLAND
18
*
NCo293
UPLAND
J59/3
NIRR
12 12 * *
.....
12
»'2------
i
Mar-May
(f
Jun-July
Aug-Oct
,:;::\@
Nov-Feb
(0130
"
M
8120
Z
'0110
>R
~100
"0
~
90
>
Ql
<II
e80
(.J
::J
CJ)
Variety
Region
Variety
Region
159/
NCo NCo
N52/N55/
3
293
310
219
805
N7 N8
Nil
NI2 Nl3 Nl4 Nl6
Coastal
S
91
94 95 96
100
92
107
107
97
104
shale
l::.
0-3 000 0 0
R1-3 1-3 1-3 1-3 1-3 1-3 1-3
Red
S98 87
sands
l::.
0-4
R1-4 1-4
Grev S68 63 113
lJO
67
109
91
72 66
sands
l::.
0 -10* -7* -3
R
1-5
1-5 1-4 1-4
Hinter- S99 93 95 88 90
91
104 102
98 Jl8
land
l::.
-4 -2 +3* -9 +4 -13* 0 0
R1-4 1-4 1-4 2-4 1-3 3-4 1-3 1-3
Mistbelt
S93
109
90 89 92 96
106
94
102
lJO
l::.
-4 -5 -7* -17 -12 0 -19
R
1-2
1-3 1-3 1-3 1-3 1-2 1-3
Effects
of
season
and
age
The mean relative sucrose yields given in Table 2 indicate
wheredifferent varietiesgrow best. Apart from important dif-
ferences
in the varieties' susceptibility to pests and diseases,
the
effect
of the season and age of the plant may need to be
considered.
Although the average yield of J59/3 was 4% less than that
of NCo 376 in the northern irrigated region, it outyielded
NCo 376when harvested betweenMarch and July (Figure 2).
This was probably due to the much greater sucrose content of
J59/3 early in the millingseason(Figure
3).
J59/3 yielded
well
in the coastal hinterland in moderately deep soils but yielded
poorlyelsewhere. NCo 293outyieldedNCo 376in the mistbelt
region
and in the coastal hinterland when harvested during
August
to
October.
The sucrosecontent of NCo 293 wasgreater
than that of-NCo 376 only at that time of the year (Figure 3).
Theaveragesucroseyield
ofNI2
wasconsiderablyhigherthan
that of NCo 376 in all regions considered. It appeared to be
advantageousto harvest N 12during the early part ofthe season
in the coastal
region,
probably becauseits sucrosecontent was
substantially higher at that time of the
year.
N13 compared
favourably with NCo 376 in the coastal dolerite and shale re-
gionswhen harvested in summer when its sucrose content was
high
relative to that of NC0376.

8
Proceedings
of The
South
African
Sugar
Technologists'
Association
-June
1985
10-
18
32 14
.~
>
Ql
III
o12
...
o
::J
CJ)
z:
16
Iro
.J:
..--
r-=""I
1--"--
I--
180
100
~
160
'I
ro
.J:
.:::.
140
32
.~
>
~
120
ro
(J
to to
I"-
ן"-
M M
oN M
~
to
0 N M
~
to
U
~
~~~
u
~ ~ ~ ~
z z z z z z z z z z
FIGURE 5 Yields of cane (A) and sucrose (6) of sugarcane varieties
irrigated adequately (unshaded) deprived of irrigation seven
months after planting at Pongola (shaded) I bars denote LSD
(P =0,05).
Effect
of
eldana
borer
Varieties 159/3, N
521219
and NII had significantly more
eldanaper
100
stalksthan did NCo 376inthe trialsat Mtunzini
(Table
3).
Although the mean number of eldana in stalks of
N13, NI4 and NI6 was higher than in stalks of NCo 376, the
differences
between
these four varieties were not statistically
significant.
The sucrose yieldofJ59/3,
N521219,
NIl,
N13and
N
16
declinedas the
level
of eldana infestation increased. This
was not the case with N 14even though it contained
30%
more
eldana than NCo 376 where the infestation was most severe.
YieldsofN14may be less
affected
than those of other varieties
due to infestations of eldana. Eldana numbers were relatively
low in stalksofN7 and N12.The superiority
ofNI2
wasmore
noticeable where eldana numbers were high than where the
level
of infestation was
low.
NCo 376 initially but stalks elongated at a similar rate after
about six months.
The
effect
of droughton commercialsugarcane varietieswas
apparent to some extent in the relationships shown in Figure
la. Poor yields were
largely
due to drought and under these
conditions, several varieties, including N7, NI2 and N13,
yielded more than NCo 376 did. This confirmed the obser-
vations made after the dry season in
1980
and
1981
(Inman-
Bamber'),
The susceptibility of varieties to water stress was evident
from the resultsofthe plantcrop ofa trial conductedat Pongola
to investigate the reaction of varieties to water stress
(Figure
5).
The severityof stresswas suchthat a number ofIarge stalks
weredead when the crop washarvested 14 months after plant-
ing.
The
number-s
of dead shoots
ofNl4,
NCo
376,
N16, NI2
and N13 were9, 5, 3, 2 and
2%
of the total respectively. Apart
from N
16,
N14yielded the most sucrose in the full irrigation
treatment but it yieldedthe leastwhen irrigationwas suspended
seven months after planting. Conversely, N12 wassuperior to
the other varieties in the dry treatment and inferior to all but
N
13
inthe
full
irrigationtreatment. N 13and N16alsoappeared
to be better adapted to the dry conditions than NCo 376 or
N
14.
N14appeared to becapableofexploiting favourable con-
ditions but had little resistance to drought. The results indicate
that N16may yield
well
underrainfedand irrigated conditions.
The data presented in
Figure
I support this
view.
A B
J59/3
o
o
-.'f
.",
N14
-,x"..--r-x
-...........
..,,,.
."
•
"'>-4:'
•.•.•_-••
__
!_--r~~
..'
.--.!
N52/219
a --
--.-------------------------
_
o
~
NCo 293
l
//
pNll
"I
.'fQ'
)( x x I
~
~
·..· x
,'rrf'
.........
)(
-,'
>y........
N16
• 0" ..
'"
••
0/11[
"",,;:,/'
~~Ji';;,«.'
0
f·
...
·· -
~,.""~"
a
~~~------
_A
_
-0-
•00
--0
,N14
,
,
o ,-
...0 ....
'0.......
,.
..
··0··
0
~'
'to
...
_.Jl-......-
-~····~
..
~.:'N16
0N12
.....
~
0
-:".
00
a
-------~:~::----;-
0
<;~-------------
o
""N13
N12
100
E
E
c
>200
t:.
to
ן"
M
o
(J
-100
Z
l:J
c
---1-
ro Coastal dolerite &
shales
>
...
.~
100
ro
>
C
Ql
Ql
~
Ql
::
-100
.J:
---I,...
.~
300 Hinterland &Mistbelt (upland)
.J:
...
g100
.J:
III
.!::
Ql
U
C
Ql
...
Ql
:;
-100
c
FIGURE 4 Mean difference in stalk height (measured at the top visible
dewlap or TVD) of certain varieties and of NCo
376,
grouped
according to age and region.
-200
L.-r--.---,---r-"'"""'T-.,---,--r--.---,--r--,
2 4 6 8 10 12 14 16 18 20 22 24
Crop
age
(months)
Northern Region
Sucroseyieldsof N16weresignificantly higher than those of
NCo 376 in all the agecategories consideredin the coastaland
upland regions, and here the difference in stalk height was
maintained
Qver
a long period. N
16
was more vigorous than
favourable for N12. The results for NCo 310 confirmed those
obtained by Lonsdale and Gosnell', .
Some varieties had distinctive patterns of stalk elongation
(Figure
4). In some
cases,
these patterns
we~e
reflected in the
relative sucrose yields when harvested at different
ages.
NI4
stalks elongated more rapidly than those of NCo 376 once the
crop was 10or more months old. This wasassociatedwith an
increase of 8% units in relative sucrose yield when harvest age
exceeded 12 months in the coastal regionbut not in the north-
ern
region.
Stalks of N12 elongatedmore
slowly
than those of
NCo 376 when crops were young but after six months, they
elongated faster than those of NCo 376 in coastal and upland
regions. In both
regions,
relative sucroseyieldsincreasedwith
the age of the crop, particularly where it was older than 18
months. In these circumstances, N12 produced
29%
more su-
crose per hectare than did NCo 376. A decline in the relative
height of stalks of N13 in the dolerite and shale soils at the
coast was associated with a decline from
108
to
94%
in the
relative sucrose yield when the age of the crop exceeded 15
months. Stalk elongation in NCo 293 and
NIl,
as in N12, ap-
peared to be more rapid than in NCo 376 in the later
stages
of
the growth
cycle
in the hinterland and mistbelt
regions.
Rel-
ative sucrose yields increased from 86 to
96%
and from 92 to
98%
in NCo 293and N II respectively whencrop ageexceeded
18 months.

Proceedings
of The
South
African
Sugar
Technologists'
Association
-June
1985
9
TABLE 3
Sucrose yield relative to NCo 376 at different levels of eldana infestation and
relative eldana numbers (as a %of NCo 376) of varieties grown on a dolerite
soil at Mtunzini
Variety
Level
of
eldana J59/3 N52/ N7
Nil
NI2 NI3 NI4 NI6
(E 100 219
stalks')
Relative sucrose yield (% of NCo 376)
E <15 94 91 95* 93
107*
106 --
E 1510 30
78*
84 -77 --IlO] 135t
E 30 to 60 74 --98* 133t 87
123*
99
E >60 71t 68 -
91
--
128*
105
Relative eldana numbers (% of NCo 376)
All levels 264*
312*
45*
190*
78
151
110 119
* denotes a significant
difference
from NCo 376 at 5% level
t denotes only one result
Conclusions
The ratooning ability of NCo 376 appears to be unsurpassed
but that of N12 appears to be just as good. Several varieties
may
yield
more sucrosethan disease-free NCo 376 if they are
grown under the conditions described in Table 4.
TABLE 4
Conditions under which sugar yields of certain varieties may exceed those of
NCo 376
Variety
Region Ageat Harvest Soil
harvest water
(mths) season supply
J5913
Northern irrigated <13 Autumn Good
NCo
293 Midlands >18 Spring Poor
N7 Coastal -Spring Poor
N8' Grey sand -Spring Poor
NI2 Coastal, hinterland, >15 Autumn and Poor to
midlands winter moderate
N13 Coastal&hinterland <15 Springand Poor
summer
NI4 Northern irrigated <13 Spring Good
NI6 Coastal, hinterland, Poor to
mistbelt --good
\
Acknowledgements
Thanks are due to
Messrs
N Hopwood,Pl Scnetler, GE Wit-
tig, R Poynton, M
Stegen,
P Hitchins and the Tongaat-Hulett
and CG Smith Sugar Companies for providing land for the
variety trials. .
REFERENCES
I. Eberhart.SAand
Russell,
WA
(1966).
Stabilityparametersforcomparing
varieties.
Crop
Sci 6: 36-40.
2. Galvanez. G
(1980).-
The genotype-environment interaction in experi-
ments of sugarcane variety trials
(Saccharum
spp.). Comparison of three
stability methods.
Proc
in! Soc Sug Cane
Techno!
17:
1152-1160.
3. Inman-Bamber,NG
(1982).
Drought tolerance of commercial sugarcane
varieties in South Africa.
Proc
SAIl' Sug
Techno!
Ass 56:
112-117.
4.
Larnusse,
1P
(1982).
Fifty-eighth reviewof the milling seasonin Southern
Africa.
Proc
SAIl' Sug
Techno!
Ass 56: 11-33.
5.
Lamusse.
1P
(1983).
Fifty-eighth reviewof the milling seasonin Southern
Africa.
Proc
SAIrSug
Techno!
Ass 57: 10-29.
.6.
Lamusse,
1P
(1984).
Fifty-ninth reviewof the milling season in Southern
Africa.
Proc
SAIl' Sug
Techno!
Ass 58: 15-33.
7. Lonsdale. 1E and Gosnell, 1M
(1976).
Growth and quality of four su-
garcane varieties as influenced by age and season.
Proc
SAIl' Sug
Techno!
Ass 50:82-86.
8. Mann, QV
(1984).
Unpublished circular of the Natal Estates
Local
Pest
and
Disease
Control Committee. November
1984.
9.
Rowland.
A1
(1985).
Unpublished report to the
Lowveld
Local
Pestand
Disease
Control Committee, February
1985.
10.
Ruschel
..
R
(1977).
Phenotypicstability of some sugarcanevarieties
(Sac-
charumspp.) in
Brazil.
Proc
In! Soc Sug Cane Techno!
16:
275-281.