Resource re‐allocation following fruit removal in cucurbits: patterns in cantaloupe melons

Abstract

SUMM.IRYThe effects of removal of fruits of marketable size on investment to male, female and vegetath-e activities, were evaluated using cantaloupe melons, Cucumis melo L., cv. Retata Degli Ortolani. Leaf and flower demography were used to examine the dynamics of potential trade..oiTs among these activities. Treated plants and controls had similar tota] biomass, but it was distributed differently. Treated plants had more vegetative biomass, both above ground and in roots, whereas control plants allocated more, in both absolute and proportionate terms, to fruits. Treated plants produced more leaves than controls, but individual leaf life expectancies were the same. Developing fruits on control plants thus seem to act as sinks at the expense of new leaves. Fruit removal also significantly stimulated production of male flowers and fruit, though these fruits contained significantly fewer, and smaller, seeds. Once fruit removal had begun, lability of floral sex expression was evident. In treated plants there was a significant increase in the production of male flow'ers. Both treated and control plants produced the same number of pistillate flowers; adjustments of fruit production occurred because of differences in the rate of successful fertilization, and later, differences in fruit set. In control plants (but not in treated plants) there were obvious tradeoffs betw'een yield components. The costs of fruit maturation in treated plants appeared to be decoupled from other yield components.

Towards an understanding of the mechanisms of tolerance: compensating for herbivore damage by enhancing a mutualism

“…In cantaloupe, pollinator behaviour and efficacy can depend on the ratios of male to female flowers, a trait that itself is very labile and sensitive to (a) timing of fruit production (El‐Keblawy & Lovett‐Doust, 1996), (b) harvest patterns (harvesting melons encourages production of new female flowers (El‐Keblawy & Lovett‐Doust, 1996), and (c) damage (Quesada et al ., 1995). Ratios varied with both plot and treatment (plot × treatment interaction in the proportion of flowers that were female measured during the pollinator observation period, F 1,110 = 5.00, P = 0.02).…”

Effect of modified endogenous ethylene production on sex expression, bisexual flower development and fruit production in melon (Cucumis melo L.)

“…Developing fruit on Cucurbita species resulted in a reduction in pistillate flower production and increased fruit abortions, while lack of fruit or fruit removal increased pistillate flower production (Avila-Sakar et al 2001;Krupnick et al 1999;Stephenson et al 1988). Similarly fruit production in the cucurbit, Lagenaria siceraria, was associated with a shutdown of subsequent flower production (Delesalle and Mooreside 1995); melon fruit removal stimulated production of male flowers and new fruit set (El-Keblawy and Lovett Doust 1996); and deflowering of early nodes in cucumber plants increased the number of simultaneously developing cucumbers on individual plants (Janoudi and Widders 1993). While we cannot always separate the effects that increase fruit set from those that increase pistillate flower production, these observations imply that the presence of integrated developmental processes regulate resource allocation, and that developing fruit may send hormonal or other signals that limit subsequent bisexual flower production or fruit set.…”

Flexible life history responses to flower and rosette bud removal in three perennial herbs

“…Prati and Schmid (2000) found a similar increase in plant size as a result of flower bud removal for the clonal herb Ranunculus reptans , while proportional allocation towards the several functions did not change. Switches in biomass allocation towards vegetative size are an expression of costs of sexual reproduction, and have been described by El‐Keblawy and Lovett Doust (1996) and Ehrlén and van Groenendael (2001).…”

“…Switches in resource allocation after manipulation have been found by Westley (1993) in the tuber‐forming species Helianthus tuberosus , by Prati and Schmid (2000) in the clonal Ranunculus reptans , and in the cantaloupe melon Cucumis melo by El‐Keblawy and Lovett Doust (1996). A natural trade‐off between life history functions in Tipularia discolor has been studied by Snow and Whigham (1989).…”