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Table 2. Fruit flesh f<strong>ir</strong>mness, starch index, Streif’s index, total soluble solids and<br />
titratable acidity of ‘Jonica’ apples as affected by rootstocks at harvest<br />
2 lentelë. Poskiepiø átaka ’Jonika‘ veislës obelø vaisiø minkðtimo kietumui,<br />
krakmolo indeksui, Streifo indeksui, bendram t<strong>ir</strong>piø sausøjø medþiagø kiekiui <strong>ir</strong><br />
titruojamajam rûgðtingumui derliaus nuëmimo metu<br />
Rootstock<br />
Poskiepis<br />
Flesh f<strong>ir</strong>mness<br />
Minkštimo<br />
kietumas, kg cm -2<br />
Starch index<br />
(scale1-10)<br />
Krakmolo indeksas<br />
(skalë 1–10)<br />
Streif’s<br />
index<br />
Streifo<br />
indeksas<br />
Total soluble<br />
solids<br />
T<strong>ir</strong>pios sausosios<br />
medžiagos, %<br />
Titratable acidity (mg<br />
malate 100 g -1 )<br />
Titruojamasis<br />
rûgðtingumas, mg malato<br />
100 g -1 )<br />
M.9 8.1 b 9.3 bc 0.07 n.s. 12.6 b 635 b<br />
M.26 7.9 a 8.9 a 0.07 12.0 a 601 ab<br />
P 22 8.6 c 9.6 d 0.07 13.3 c 586 a<br />
P 59 8.6 c 9.4 c 0.07 13.2 c 630 b<br />
P 60 8.1 b 9.2 b 0.07 12.6 b 603 ab<br />
* Means within columns followed by the same letter do not differ at α = 0.05<br />
* Tarp skiltyse ta paèia raide paþymëtø skaièiø nëra esminiø sk<strong>ir</strong>tumø, kai α = 0,05.<br />
There was no evident effect of rootstocks on fruit maturity at harvest as determined<br />
by Streif index and starch index (Table 2). However, fruits from trees on P 22<br />
tended to have less starch and lower F/RS values. At harvest flesh f<strong>ir</strong>mness of<br />
apples from trees on rootstocks P 22 and P 59 was the highest. Respectively, the<br />
lowest ones were observed for M.26 rootstock. In opposition to those findings, in<br />
both reports of Drake et al., (1991) and Autio (1994) it was evident that the more<br />
dwarf rootstock the higher fruit flesh f<strong>ir</strong>mness. According to Johnson (1992), rootstock<br />
and flesh f<strong>ir</strong>mness are ind<strong>ir</strong>ectly related through a negative correlation – fruit<br />
size and flesh f<strong>ir</strong>mness. Presented study seems to conf<strong>ir</strong>m such relationship, small<br />
apple fruits originating from trees on P 22 rootstock were having the highest flesh<br />
f<strong>ir</strong>mness at harvest.<br />
‘Jonica’ fruit from trees on rootstock M.9 reached harvest maturity usually 3–<br />
5 days earlier than on other rootstocks (unpublished results), and tend to obtain the<br />
lowest values of Streif’s index for fruits from trees on P 22.<br />
Rootstock did affect the content of carbohydrates and organic acids (Table 2).<br />
Soluble solids content was the highest for fruits from trees on P 22 and P 59. This<br />
conf<strong>ir</strong>m the results of Autio et al., (1996), who stated that fruits from trees on<br />
rootstocks from P series tended to contain more soluble solids than from M.26 or<br />
M.9, respectively. Results of cited above author and of our study are in opposition<br />
to earlier reports stating that fruits from trees on M.9 and M.26 tended to have<br />
more soluble solids (Autio 1994). Some authors claimed that soluble solids content<br />
was negatively correlated to trunk cross sectional area (Autio et al., 1996). Such<br />
tendency could be observed in a reported study only for fruit from trees on P 22<br />
and P 59.<br />
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