A Progress report on citrus rootstocks studies in Sardinia

This paper reports further results of long-term research on citrus
rootstocks in Sardinia started in 1969. Two rootstocks (sour orange and
« Troyer » citrange) have been compared for « Hamlin » and « Frost Navel »
sweet oranges, and «Frost Eureka» lemon. Five rootstocks (sour orange,
« Troyer» citrange, «Rubidoux» trifoliate orange, « Orlando» tangelo, and
« Palestine» sweet lime) were also compared for « Frost Marsh» grapefruit.
The growth and productivity for all of the stock/scion combinations were
evaluated from 1973 to 1977. The results showed that both growth and
productivity of «Frost Navel» orange were better on «Troyer» citrange
than on sour orange. «Hamlin» orange productivity was also improved by
« Troyer» citrange, while sour orange increased the tree-growth. In « Frost
Eureka» lemon both growth and productivity were increased by sour orange.
The fruit quality was normally improved by «Troyer» citrange in comparison
with sour orange. The growth and fruit production of «Frost Marsh»
grapefruit were mainly increased by «Orlando» tangelo and «Palestine» sweet lime. Intermediate growth and productivity were found on sour orange
and «Troyer» citrange. The lowest growth and yield were recorded on
« Rubidoux» trifoliate orange, but it and « Troyer» citrange improved fruit
quality.