Cayenne pepper (Capsicum annuum L.) is one of several chile pepper pod types grown in New Mexico. Other pepper pod types include long red mild, long green mild, paprika, and long green hot [New Mexico Agricultural Statistics (NMAS), 2010]. Cayenne peppers are the main ingredient in chile mash, the precursor to most Louisiana-style hot sauces (Bosland and Strausbaugh, 2010). Many commercial cayenne pepper cultivars have an indeterminate growth habit and therefore each plant has many pods of different ages that do not ripen to red simultaneously. This necessitates multiple, costly hand harvests of newly matured red pods during the growing season (Funk and Marshall, 2012). Increasing labor costs make it difficult for New Mexico pepper producers to stay competitive with domestic and foreign markets. Labor costs have created a shift toward less costly mechanical harvest (Funk and Walker, 2010). Reducing labor inputs by using mechanical harvest technology is one way that New Mexico producers can maintain a more competitive position in the U.S. and world pepper market (Wall et al., 2003b).
In addition to its indeterminate growth habit, cayenne pepper pods have characteristics indicative of both climacteric and non-climacteric fruits (Biles et al., 1993; Villavicencio et al., 1999). It is therefore designated as semiclimacteric. This characteristic of cayenne limits the efficiency of once-over machine harvest because green pods harvested before the breaker stage will not turn red. Pod maturity must be at least to the breaker stage at the time of mechanical harvest to ensure proper pod pigmentation. One goal of New Mexico growers is to maximize red pod yield, whereas another is to increase red pod percentage, which will reduce the cost of sorting and removing green pods in a once-over mechanical harvest system.
Traditional plant breeding may be another way to improve the efficiency of mechanical harvest and help change the staggered pod development of cayenne. There are cultivars that exhibit determinate growth characteristics, but the overall quality and yield of these cultivars are inferior when compared with indeterminate cultivars (Arturo Jurado, Jurado Farms, personal communication, 22 Feb. 2009). The release of new determinate cultivars through traditional plant breeding is time-consuming and costly, so this study will focus on managing an indeterminate hybrid cayenne pepper cultivar to synchronize red fruit maturity necessary for mechanical harvest.
One way to manage indeterminant cayenne pepper pod maturity is by using plant growth regulators (PGRs). Ethylene, one of the primary PGRs involved in fruit ripening, has been shown to increase red pod synchronization when applied to paprika pepper before harvest at the rate recommended by the product (ethephon) label (Kahn et al., 1997). However, results involving ethephon and fruit maturation are highly variable (Alexander and Grierson, 2002). Ethephon has been used to enhance the color development rate in cayenne and paprika peppers (Krajayklang et al., 1999), but did not improve color development in other pepper cultivars (Hoyer, 1996). When ethephon is used to synchronize red pod development, it is most effective if pods are allowed to mature to the breaker stage. Ethephon treatments, however, often cause reduced yields and plant vigor (Kahn et al., 1997). Although ethephon can boost red pod percentage, it can also cause leaf yellowing and abscission of young pods and flowers that may reduce the total yield (Kahn et al., 1997). As a result, many pepper producers have chosen not to adopt PGRs as a result of the perceived risk.
Cantliffe and Goodwin (1975) demonstrated that ethephon applied to paprika-type chile peppers before harvest significantly increased the ratio of red to green pods. A once-over mechanical harvest removes all pods from the plant so undesirable green pods must be sorted out later. Therefore, an increased ratio of red pods will reduce both postharvest sorting time and waste of green pods. The practice of applying ethephon before mechanical harvest could increase the percentage of red pepper pods; however, ethephon is not widely used in New Mexico pepper production because results are variable and, in some cases, treatments actually reduce yields (Alexander and Grierson, 2002; Kahn et al., 1997).
Kahn et al. (1997) also proposed that ethephon applied several weeks before harvest could increase red pod percentage, allowing for a once-over mechanical harvest because the number of undesirable green pods is reduced. Cantliffe and Goodwin (1975) studied ethephon as a ripening agent for red pod synchronization, whereas Kahn et al. (1997) focused on ethephon-induced abscission of young green pods. Kahn’s results, similar to Cantliffe and Goodwin (1975), suggest that ethephon treatments increased red pod ratio because of significant green pod abscission. However, because of this significant green pod abscission, total yield was reduced (Kahn et al., 1997).
As a result of its indeterminant growth habit, we suggest that a midseason application of ethephon can also cause immature pod and flower abscission. However, there is no information in the literature regarding an early-season, controlled abscission of cayenne specifically designed to synchronize red pod development and increase red pod yield and percentage by the end of the season. Therefore, the hypothesis for this study is that midseason application timings of ethephon will increase both red pod percentage and total red pod yield for an indeterminate-type cayenne pepper cultivar. Midseason application of ethylene will serve as a controlled abscission agent and will cause flowers and immature pods to abscise. These early-season pods will not contribute greatly to the overall yield, and their removal will help synchronize the cayenne crop. The plants will quickly produce replacement pods in a shorter period of time causing simultaneous ripening at the end of the season. One objective of this study is to evaluate the effects of four different application timings of ethephon on their ability to increase red pod yield and percentage while maintaining market quality. Another objective is to evaluate the impacts of ethephon application on the total fresh weight of green and non-marketable pods.
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