SWEET    POTATO     RELEASES    FROM     AIYURA

By Will Lungat Akus, Horticulturist,  Highlands Agricultural
Experiment  Station, Aiyura, E.H.P.

INTRODUCTION

Most of the people in the high- lands of Papua New Guinea de- pend on sweet potato for their living.  This justifies re- search to find high yielding varieties with acceptable flavours for farmers.

Work	on sweet potato evalu- ation	 started in the late
1950's at the Highlands Agri- cultural Experiment  Station at Aiyura and has expanded since then.  A collection of over 700
Papua New Guinean sweet potato
varieties  is maintained  at Aiyura.  Numerous experiments have been carried out by Aiyura staff on sweet potato, at
Aiyura	and elsewhere  in the highlands.	Twenty-two  of these
trials have been variety trials in which 48 varieties have been tested.

A number of varieties have now been selected and are recom- mended for the highlands
region.  These varieties  are
being distributed  from Aiyura
for farmers to tryout  in their own gardens.

SELECTION METHOD

Varieties	have been selected after evaluation  of tuber
yield,	eating quality and res- istance		to sweet potato leaf scab.

All selected varieties have been  evaluated in at least ten experiments  and have been found to be good tuber yielders.   The mean fresh tuber yields ranged from 20 to 30 t/ha but yields
of over 40 t/ha have been re-
corded.  The dry matter content
averaged between 29 and 32.5
percent.

Testing and eating quality
tests proved that the varieties
have good eating quality and generally  acceptable  flavours.

The Papua New Guinea highlands is considered  a healthy area
for sweet potato growing.  How- ever, sweet potato leaf scab, a fungal disease, can sometimes cause major leaf disorders.
All	recommended  varieties  are at least tolerant to sweet potato	leaf scab.

Other	factors such as tuber shape,		storability  and maturity time have been considered
before varieties have been re-
leased.

VARIETIES  RELEASED

The varieties  recommended  and released	are:

1.  Markham 1
2.  Merikan
3.  Naveto
4.  Serenta

Markham 1                             Merikan

Originally  this variety was called Markham, but to iden- tify it correctly from other

This	is a variety widely grown in the Eastern highlands.   It is an introduced variety but

varieties  also called Markham,

the records about its origin do

it is now called Markham 1.

not all agree with each other.

This was collected  from the

Markham Valley but the origin

Following  its introduction  in

is not known.

the mid 1950's, extensive  tests

were done to see if it was

Markham 1 has a pale yellow

frost resistant.   It was found

tuber skin with purple pigment sometimes present on young

not to be frost resistant, however it was high yielding.

tubers.  The tubers have a good

shape and the flesh is purple

The tubers have a whitish-

with concentrations  of white

yellow skin which turns to

spots throughout.   This very characteristic  colour makes it

brown with age.  The flesh is yellow.   The tubers have a good

easily identifiable  from other
varieties.   Leaves are heart-

average size and are oval in
shape with smooth skin.  It is

shaped and usually green with

a good eating tuber.  The

purple spots sometimes present

leaves are green with red leaf

on young leaves.

veins and are heart-shaped.

MARKHAM 1 tubers and vines

MERIKAN.	 This is an introduced variety now grown in many highlands gardens.	A good eating tuber.

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Naveto

This variety originated  in the Benabena Valley of the Eastern Highlands Province and has been found to do well throughout the highlands.   The tubers have a pink skin which turns brown
with	age.  The flesh is white. The size of the tubers varies but is generally  large.  Young leaves are purple but turn
green as they grow older.  Leaf shape is palmate  (i.e. like
spread fingers) .

When	progressive  harvesting  (or mumuting)	is the technique
used, then Naveto is the best of the four recommended  var- ieties to use.  This is because Naveto will continue to produce tubers for up to 18 months if left in the ground.

Serenta

There are two types of Serentq and both are traditional to the Eastern Highlands Province.
One type is higher yielding
than the other.  Only the high
yielding	Serenta is available for distribution.

The skin colour of young tubers varies but it is usually white and turns to brown as tubers mature.  Tuber flesh is yellow- ish-white.  Serenta has large tubers with reasonable shape. The young leaves are purple
but quickly turn green with ma-
turity.  Leaf shape is palmate.

This variety is already wide- spread		in the highlands but is known	by different names.

NAVETO is a good variety to use when progressive  harvesting  (or mumu- ting) is practised.   It is also very high yielding.

SERENTA	is a   traditional  variety  already widespread  and well-liked in the highlands.

ANTING MATERIAL

three from the United States

and four from Nigeria, have

anting material for each of

been tested.  Two Nigerian

ese varieties is available  in

varieties have out-yielded

fficient quantities  all year

Merikan, one of our best local

ound from Aiyura.  There is

varieties  in two trials.

charge for the planting

Further tests are planned for

terial but if material is to

the introduced  varieties before

sent to other provinces

they are released.   Trials are

eight charges will have to be

also being done on some of the

t by those requesting ma-

Papua New Guinea varieties  at

rial.  Requests for planting

different altitudes and climatic

terial  should be sent to:

The Officer-in-Charge
H.A.E.S.
P.O. Box 384
Kainantu,   E.H.P.

zones throughout  the highlands.

We expect that in future researchers		will find better yielding		and more suitable varieties		for the sweet potato growers	in the highlands.

e varieties being distributed
om Aiyura have given high

lds	at some locations in the hlands	but not others.
kham  1 for example has done y  well at several locations the Southern Highlands Pro- ce  but poorly in the Simbu vince.   Hence growers should t the Aiyura releases and
ess whether they are better n their own varieties  under ir growing conditions.

THER WORK

et potato evaluation  is an going  function at Aiyura. ently  seven varieties,

ACKNOWLEDGMENTS

Mr Allan Kimber, who was an ag- ronomist	 at Aiyura until recent- ly, collected many of the sweet potato	varieties  in the Aiyura collection	and did some of the variety		testing.  Other Aiyura agronomists	 who have tested
sweet potato varieties  are Beka
Siki, Terry Quinlan and Clement
Tumana.  Photographs  were taken by Brian Calcinai,  a horticult- urist at Aiyura.

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