Origin

Starting in 1998, the National Institute for Agricultural and Livestock Forest Research (INIFAP) promoted external projects aimed at developing high-yielding varieties of dry calyx jamaica for regions with high productive potential for this species in the Mexican Republic. The project began with the introduction of national and international germplasm, to identify useful parents as a source of yield genes and tolerance to ‘pata prieta’ (Phytophthora parasitica).

These donors of yield and tolerance were crossed with creole varieties, of high demand among producers, marketers and consumers, low yielding and susceptible to the mentioned diseases. To generate the Quinba R-TC variety, the genealogical method (pedigree) consisting of hybridization and selection was used. The Giant line, with a large calyx and dark purple color, was used as the donor parent of the yield genes. This line came a selection made in a variety of jamaica Sudan creolized type, collected in the Costa de Guerrero in 1998.

As a tolerant parent to ‘pata prieta’ (Phytophthora parasitica), the creole variety registered under the name of Tecoanapa (Figure 1) (^{Ariza et al., 2014}) was used, which has demand in the local and national market, but with the disadvantage of having a small calyx and poor yield (^{Barrios et al., 2016}). The hybridizations to obtain the simple cross were carried out in the years 2003 and 2004 and from 2004 to 2008 the generational advance was carried out and individual selections were made in the segregating populations, each selection was massively reproduced to eliminate the out-of-type plants.

Figure 1 Comparison of plants and fruits of the Jamaican varieties Quinba RTC and Tecoanapa (creole from Guerrero) in physiological maturity. 

Jamaica plants planted in potential areas are highly sensitive to photoperiod, which is why all the work was done in the S-S cycles (July to December) in the INIFAP Experimental Fields of Iguala and the Higher Agricultural College of the Estado de Guerrero (CSAEGRO).

Adaptation and yield

The uniform line named Sel-22 that gave rise to the Quinba R-TC variety, was obtained in 2007. The first evaluations of the line for adaptation and yield were made in the mentioned experimental fields; as of 2011, they were made in producer fields, due to their good agronomic behavior and similar to the creole, it was named ‘improved creole’. The line was evaluated in a regional yield trial in 2011 and 2012 along with other high yield materials of different types, colors, plant and calyx sizes (Table 1).

The variety develops under the same conditions as the creole, preferably with average temperatures ranging from 25 to 38 °C with a rain regime of 900 to 1 400 mm per year, it also tolerates little precipitation (between 600 and 900 mm) and average temperatures below and above the recommended, due to its rusticity, it adapts to a wide variety of soils, since it is an undemanding crop, but it is more productive in deep soils where it can freely develop its root system.

During its vegetative development, sandy loam soils, hot and dry climates, low humidity and a lot of sunlight are preferred it does not tolerate waterlogged soils. Under the optimal conditions described, the Quinba R-TC variety can double its yield (^{Barrios et al., 2016}; 2017).

Plant characteristics

The plants of the Quinba R-TC variety are tall (Figure 2), of a late biological cycle (they bloom from November), they are tolerant to ‘pata prieta’ (Phytophthora parasitica) and with a larger calyx but with a color similar to of the Tecoanapa (creole) variety, which gives it preference in the market (Figure 3). Under storm conditions in the coastal regions of the Mexican Pacific, the Quinba RTC variety should be sown preferably at the beginning of the storm and until July 15, since as it is a variety that responds to the photoperiod, the longer it lasts in the field, the more the plant grows, which favors higher yields (^{Barrios et al., 2017}). The characterization of the line was made, based on the descriptors proposed in the guide published by ^{SAGARPA-SNICS (2014)} for this species.

In 2016, the National Seed Inspection and Certification Service (SNICS) was requested to register a new variety of Jamaica, granted under number 3572-JAM-006-010218/C and the official name of Quinba R-TC, derived from the cross from the Gigante x Tecoanapa lines (creole from Guerrero). In the Iguala de Guerrero Experimental Field, basic seed of this new variety is available.

Figure 2 Jamaica: Quinba R-TC variety. 

Figure 3 Plant of the improved variety Quinba R-TC(a) and branches with calyxes of the regional creole (b) compared to Quinba R-TC and others. 

Conclusions

A new highly productive variety of jamaica was generated, which exceeded the yield of the control variety by 80%, the attributes of the new variety are: growing four days earlier, calyx color similar to the regional creole and calyx 70% larger and with little pubescence.