Floral display and effects of natural and artificial pollination on fruiting and seed yield of the tropical biofuel crop Jatropha curcas L.

Abstract

Floral display and effects of natural and artificial pollination on fruiting and seed yield of the tropical biofuel crop Jatropha curcas L. Abstract Jatropha curcas L. is a tropical tree grown on large scale as a potential biofuel seed crop. However, little information on the reproductive ecology of the species is available. This lack of knowledge makes it hard to predict yield. The higher number of male flowers than female flowers results in a very low yield. In this context, field experiments were conducted in mature (site 1) and young (site 2) plantations in Zambia and mature plantation (site 3) in Malawi to study flowering characteristics and the effect of pollination methods on the fruiting and seed yield of J. curcas. Pollination treatments were open pollination, autogamous pollination, self-pollination, cross-pollination and pollen supplemented open pollination. The result showed J. curcas is not only of protandrous nature as reported earlier. The male female flower sex ratio was 17 : 1, 22 : 1 and 10 : 1, respectively, for site 1 and 2 in Zambia and site 3 in Malawi. The mean flower longevity periods were 1.80 AE 0.07 days for male and 4.5 AE 0.18 days for female. Fewer fruit set and seed yield were recorded from autogamous pollination in Zambia sites. In the case of Malawi, more matured fruits resulted from autogamous pollination but the fruits contained fewer seeds. High fruit and seed yield were recorded for open pollination similar to pollen-supplemented pollination at Zambia sites, which indicates there was no pollen limitation in these sites. In the Malawi site there was no seed yield difference between pollination treatments. The experiment showed that J. curcas can be both protandrous and protogynous and able to produce seeds through both self-and cross-pollination. The natural fruit set and seed yield indicates that stimulating natural pollination will improve J. curcas fruit set and seed yield. IntroductionUnderstanding the flowering and breeding system of agricultural crops has a strong economic and ecological significance, and it has implications for both crop and pollinator management (Strickler, 1999). In plant breeding mechanisms there are three types of possible mating: geitonogamy (self-pollination), xenogamy (cross-pollination) and apomixis (asexually without pollen contact to the stigma) (Richards 1997). Different mating mechanisms may result in different fruit and seed yields (Trueman & Turnbull, 1994;Rao & Raju, 2002;Bieniasz, 2007;Hassan et al., 2007;Kaushik et al., 2007;Hui-Juan et al., 2008).Jatropha curcas L. is an insect-pollinated oil-producing crop and oil yield therefore directly depends on successful flowering and pollination success (Carels, 2009) Jatropha curcas is still a semi-wild plant and basic agronomic research on cultivation practices to optimize seed and oil yield is only emerging recently (e.g., Achten et al., 2008Achten et al., , 2010Maes et al., 2009 Information regarding flower phenology, pollination mechanisms, fruit formation and development to final ripenin...

Tree or shrub: a functional branch analysis of Jatropha curcas L.

“…However, there are no data available for biomass partitioning in the generative stage (harvest index). The relationship between inflorescence size, sex ratio, fruit maturation (yield) (Negussie et al 2014), and plant architecture is important. For instance, in apple and pear trees the reproductive and vegetative branches are different (Costes et al 2006), while for coffee trees the branches bearing flowers and fruit grow horizontally from the stem (van der Vossen and Herbert 1985; Cilas et al 2006).…”

Insufficient Evidence of Jatropha curcas L. Invasiveness: Experimental Observations in Burkina Faso, West Africa

“…1), as in other Sahelian countries within the same agroecozone, e.g., Mali. Similarly, in the southern parts of Africa, which are also seasonally dry, it also flowers in the rainy season, which there is predominantly between November and April [54].…”

Is there life after hype for Jatropha? Exploring growth and yield in Indonesia

“…The second and subsequent cycles share many similarities and resemble other miracle new crops, such as Argania spinosa and Moringa oleifera (Achten et al, 2014).…”

“…Biofuels have been promoted as potential sources of energy that can be produced in an environmentally and socially sustainable way. An example of the impact of these concerns can be seen in the European Energy and Climate Change Policy that aims to cover 10 % of the European transport fuel demand with biofuels by 2020 (Gui et al, 2008;Achten et al, 2010a;Pradhan and Ruysenaar, the lack of high yielding planting material (Iiyama et al, 2013;Achten et al, 2014;Edrisi et al, 2015). The problem is that reliable production data is lacking (Edrisi et al, 2015), especially in regards to breeding, management, and pest and disease susceptibility (Achten et al, 2010a;Achten et al, 2014;Van Eijck et al, 2014a;Edrisi et al, 2015).…”

“…Many of the envisaged benefits have not materialised. Yields of 12 t ha -1 for example have been claimed and global predictions showed yields of only 5 t ha -1 (Achten et al, 2014). The problem is that expectations were not based on field performance and validated scientific knowledge (Edrisi et al, 2015).…”