California Lemon Rootstock Research Reported

Researcher Glenn Wright recently reported how various rootstocks for lemon trees producing fresh market fruit compared for yield and other qualities in three California locations with different climates. Wright is a University of Arizona associate professor and Extension specialist for tree crops.

SANTA PAULA
Santa Paula’s warm summer Mediterranean-like climate had the following results:

• Macrophylla and Volkameriana had the greatest yield. Carrizo and several other Poncirus hybrids had lesser yields. C-22, Brazil Sour Orange and trifoliate orange had the least yields.
• C-22 had good yield efficiency — 50% to 60% reduction in tree size and a 45% reduction in yield compared with Macrophylla and Volkameriana. Citremon 1449, C-54, X-639 and C-35 were also good.
• Sunki x Flying Dragon, X-639, Volkameriana and Citremon 1449 had the best fruit size. Trees on Rich 16-6 produced the smallest fruit.

LINDCOVE
Research in Lindcove, a hot summer Mediterranean-like climate, provided these results:

• In the absence of Macrophylla and Volkameriana, C-22, Citremon 1449, C-57 and C-35 had the greatest yields. Several other trifoliate hybrids had lesser yields. X-639 and sour orange had the least yields.
• Citremon 1449, C-22, C-35, Sunki x Flying Dragon and Rich 16-6 trifoliate had the best yield efficiency.
• Fruit size for all the rootstocks was similar, but Bitters and Carrizo had slightly larger fruit size. 

THERMAL
Thermal, with a hot desert climate, had the following results:

• Macrophylla and Volkameriana had the greatest yield. Citremon 1449 had lesser yields. C-22, Sunki x Flying Dragon, C-54 and several others had lesser yields. Brazil Sour Orange and Carrizo had the least yields.
• Citremon 1449 had good yield efficiency vs. Volkameriana — 23% reduction in tree size and a 12% reduction in yield. Citremon 1449 does not compare well with Macrophylla.
• Trees on Volkameriana and Macrophylla had the best fruit size. Bitters and C-146 produced trees with good fruit size, but not as good as Volkameriana and Macrophylla. X-639 has the smallest fruit size.

Wright’s presentation was part of the Citrus Research Board of California’s 2023 Citrus Growers Educational Webinar Series. His talk also reported on lemon scion research.

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