Unraveling the mystery of non extraction of honey from modern sunflower hybrids

Abstract

Sunflower (Helianthus annuus L.) has largely failed as a source of extractable honey from present day cultivated hybrids in India since 1999. So, the amount and rhythms of nectar secretion measured as dry nectar sugars (DNS) of 6 hybrids and 2 old populations were evaluated. Three day old florets (DOF) produced maximum DNS (0.891 mg/floret) at 1000 h and in the outermost ring of the capitulum (0.917 mg). Per floret production of DNS in populations was 17.7% higher (0.974 mg) than hybrids (0.803 mg). Population HS-1 and Morden produced maximum DNS per floret (1.004 and 0.943 mg) and DK-3849 was the only comparable hybrid (0.993 mg). Noticeable reduction (14.2–37.5%) was recorded in the rest of hybrids, maximum being in HSFH-1183 (37.5%) followed by Pioneer 64A57 (33.1%). Per hectare, DNS production too was higher (10.2%) in populations (174.3 kg) than hybrids (145.8 kg) although hybrid HSFH-848 was most copious (200.0 kg/ha) followed by populations Morden (188.1) and HS-1 (160.6 kg), other 5 hybrids yielding a low DNS of 116.3–142.5 kg/ha. Populations outperformed hybrids in all DNS production factors viz. per floret (0.974 mg), by florets in their life cycle of 3 days (2.921 mg), per capitulum (3137.5 mg) and per hectare basis (174.3 kg). High DNS producing old populations Morden and HS-1 recorded lowest honey bee abundance (0.33 and 0.47 bees/capitulum/minutes−2) than hybrids (0.51–0.69 bees) except Pioneer 64A57 which despite the lowest DNS (116.3 kg/ha) recorded maximum abundance (0.69 bees), indicating their preference for pollen. Studies attribute non extraction of honey to lower nectar production by a majority (83.3%) of new hybrids than old populations.