Cuphea Production and Management - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 293

Cuphea Genetics, Breeding, and Improvement

In a previous review, Phippen [ 46 ] provided an excellent review of research
regarding cuphea germplasm sources, genetics, and breeding; so, we will only
briefly address it here. PSR23 cuphea is the primary focus of recent breeding
work that has been done in Illinois at Western Illinois University and in Minnesota.
Also, as cited by Phippen [ 46 ], some breeding work continues in India on
C. procumbens for seed oil production, in South America where
C. carthagenensis and C. glutinosa are being explored for medicinal purposes,
and in Japan where C. leptopoda is being researched for food uses. Cuphea species
chromosome number varies from n

54 [ 19 ]. Cuphea lanceolata and
C. viscosissima have a chromosome number of n

¼ 6to n ¼

6 which allows interspecific
hybrids between these species to be fertile [ 47 , 48 ]. Cuphea llavea and C. wrightii
var. wrightii have a chromosome number of n

¼

¼ 22. Cuphea carthagenensis and

C. tolucana have a chromosome number of n 12, respectively [ 19 ,

47 ]. Most cuphea germplasm accessions have wild characteristics not suitable for
direct utilization and commercial production such as seed dormancy, obligate cross
pollination, seed shattering, and indeterminate growth habit prone to enhancing
seed shatter and low seed yields. Because of cuphea's indeterminate growth and
flowering, seed development can extend over weeks to even months [ 16 ].
Morphological variability among accessions of C. viscosissima is limited, but
differences have been observed in plant mass, height, dormancy, seed shatter, seed
yield, oil content, and oil composition [ 49 , 50 ]. Important breakthroughs toward
domestication of cuphea have been accomplished in the last two decades. Several
lines with suitable agronomic characteristics such as low seed dormancy self-
pollination, partial seed shattering, and high oil content have been released, such
as lines LN-183 ( C. lanceolata Ait . ), VL-90 to VL-95, VL160, VL186, and PSR23
( C. viscosissima Jacq. x C. lanceolata f. silenoides W.T. Aiton) [ 3 , 4 , 51 , 52 ]
(Table 13.4 ). Also Knapp et al. [ 53 ] and Tagliani [ 54 ] developed C. viscosissima
fatty acid mutant germplasm lines with low capric and high caprylic, lauric, and/or
myristic acid.
However, seed shattering, self-incompatibility, and indeterminacy are problems
that need to be solved to improve cuphea yields and expand commercial production.

¼ 8 and n ¼

Cuphea Physiology

Cuphea Seed Germination and Development

Most of the wild species of cuphea have seed dormancy. Several wild species of
cuphea exhibit primary seed dormancy, which leads to poor seedling establishment
[ 55 ]. Seeds of C. viscosissima have been shown to lose most of their dormancy in 4-
6 months of cold, moist, storage, or after 4 years of dry storage [ 56 ]. Seeds from