Theme 2-3: Forage Production and Utilization--Poster Sessions

Description

A green manure crop, sunn hemp (Crotalaria juncea L.), legumes, has a nematode-suppressive effect. It is also used as feed in India. However, it is not used as feed in Japan because it contains natural toxins: Pyrrolizidine alkaloids (PAs). PAs has the negative effects for not only livestock but also human health. The PAs, which are abundant in sunn hemp seeds and which are contained only slightly in leaves and stems. Therefore, if sunn hemp harvested before flowering, then no poison problem is posed by PAs. However, if it is harvested at the podding stage, a poisonous concentration of PAs occurs. For increasing yield, it is necessary to harvest it as late as possible. For obtaining both safe feed without PAs and increase in yield, we clarify when the PAs concentration will be increased from flowering to podding.

We cultivated the varieties of crotalaria which are distributed currently in Japan and USA for green manure during July–October 2019. We observed the period from flowering to podding. We harvested bud, flower, immature pods (under 15 mm) and pods. Then one PAs component that is abundant in seeds, the trichodesmine content, was analyzed.

In the case of late July seeding, the first flowers blossomed in about 50 days after seeding. No difference was found between varieties. The flowers wilted about two days after flowering. The ovaries grew to immature buds about five days after flowering. Trichodesmine in seeded seeds was greater than 1000 mg/kg. That in buds, flowers, and immature pods was less than 1.0 mg/kg. Also, that in pods (over 15 mm length) was greater than 10 mg/kg.

If harvested within one week from the first flower blooming, then sunn hemp can be used as forage with low PAs concentration.

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When the Natural Toxin Concentration in Crotalaria Increase in Japan?

A green manure crop, sunn hemp (Crotalaria juncea L.), legumes, has a nematode-suppressive effect. It is also used as feed in India. However, it is not used as feed in Japan because it contains natural toxins: Pyrrolizidine alkaloids (PAs). PAs has the negative effects for not only livestock but also human health. The PAs, which are abundant in sunn hemp seeds and which are contained only slightly in leaves and stems. Therefore, if sunn hemp harvested before flowering, then no poison problem is posed by PAs. However, if it is harvested at the podding stage, a poisonous concentration of PAs occurs. For increasing yield, it is necessary to harvest it as late as possible. For obtaining both safe feed without PAs and increase in yield, we clarify when the PAs concentration will be increased from flowering to podding.

We cultivated the varieties of crotalaria which are distributed currently in Japan and USA for green manure during July–October 2019. We observed the period from flowering to podding. We harvested bud, flower, immature pods (under 15 mm) and pods. Then one PAs component that is abundant in seeds, the trichodesmine content, was analyzed.

In the case of late July seeding, the first flowers blossomed in about 50 days after seeding. No difference was found between varieties. The flowers wilted about two days after flowering. The ovaries grew to immature buds about five days after flowering. Trichodesmine in seeded seeds was greater than 1000 mg/kg. That in buds, flowers, and immature pods was less than 1.0 mg/kg. Also, that in pods (over 15 mm length) was greater than 10 mg/kg.

If harvested within one week from the first flower blooming, then sunn hemp can be used as forage with low PAs concentration.