Effects of Defoliation on Sex Differentiation in Oil Palm Clones

Abstract

SUMMARYDefoliation affected inflorescence production by oil palms, causing a decrease in sex ratio (ratio of female inflorescences to total) and an increase in abortion rate. Clones differed in response to defoliation. One of seven clones showed no increase in abortion rate; in one clone there was a tendency for female inflorescences to abort in greater numbers than males. The change in sex ratio occurred much sooner after defoliation in some clones than in others, and comparison of flowering records with dissections done at the time of defoliation indicated that inflorescence sex was affected at more than one stage in development. This has important consequences for attempts to predict yields.

On yield gaps and better management practices in Indonesian smallholder oil palm plantations

“…The timing of sex determination varies among experiments, research sites and planting materials, ranging from 29 to 30 months before harvest (Broekmans, 1957) to 20 months before harvest ; Figure 2.2). Corley et al (1995) found that the timing of sex determination varies among clones: either at bract initiation, Leaf -29, or just before first rachilla initiation, Leaf -10, or both. This led Corley and Tinker (2016: 121) to speculate that sex differentiation occurs at Leaf -29 but is reversible up to Leaf -10 (Cros et al, 2013).…”

“…The number of ripe bunches available for harvest is determined by 1) the number of inflorescences initiated (which in turn depends on the rate of leaf production; Gerritsma and Soebagyo, 1999); 2) sex ratio (Heel et al, 1987;Corley et al, 1995;Adam et al, 2011); 3) abortion of female inflorescences before anthesis ; and 4) failure of developing bunches between anthesis and bunch ripeness (Combres et al, 2013).…”

“…Developing inflorescences are most sensitive to abortion 4-6 months before anthesis, which coincides with the onset of floral organ development and elongation (Broekmans, 1957). Whereas several authors reported a preferential abortion of female inflorescences during (part of) the sensitive period of inflorescence development (Bredas and Scuvie, 1960;Pallas et al, 2013), others observed preferential abortion of female inflorescences only in specific lines (Corley et al, 1995), preferential abortion of male inflorescences (Legros et al, 2009b), or equal abortion rates for inflorescences of both sexes (Henry, 1960). Inflorescence abortion rates of 25-40% were measured in young mature palms that experienced prolonged dry seasons in Nigeria, decreasing to 5-10% in palms > 15 YAP (Broekmans, 1957).…”

Description of the Immature Stages and Redescription of the Adults of Ancognatha scarabaeoides Erichson (Coleoptera: Scarabaeidae: Dynastinae), A Member of the Soil White Grub Assemblage in Colombia

“…Defoliation of the top level of the canopy is very detrimental, and the plant may need up to 2 years to rebuild the canopy (Young 1977;Corley 1983;Henson 1990;Darus & Basri 2000). Thus canopy defoliation reduces plant size and biomass (Young 1977;Henson 1991;Dufrene & Saugier 1993;Corley & Donough 1995).…”

Life History Traits and Damage Potential of an Invasive Pest Acharia fusca (Lepidoptera: Limacodidae) on Oil Palm

“…Defoliation of the top level of the canopy is very detrimental, and the plant may need up to 2 yr to rebuild the canopy (Young 1985, Corley 1983, Henson 1990, Darus and Basri 2000. Thus, canopy defoliation reduces plant size and biomass (Young 1985, Corley andDonough 1995). Measurement of consumption rate can be used to estimate losses caused by insect herbivores in crops (Crawley 1989, Kapari et al 2006.…”