Germination Biology of Sesbania (Sesbania cannabina): An Emerging Weed in the Australian Cotton Agro-environment

Abstract

Sesbania [Sesbania cannabina(Retz.) Pers.] is a problematic emerging weed species in Australian cotton-farming systems. However, globally, no information is available regarding its seed germination biology, and better understanding will help in devising superior management strategies to prevent further infestations. Laboratory and glasshouse studies were conducted to evaluate the impact of various environmental factors such as light, temperature, salt, osmotic and pH stress, and burial depth on germination and emergence of two Australian biotypes ofS. cannabina. Freshly harvested seeds of both biotypes possessed physical dormancy. A boiling-water scarification treatment (100±2 C) of 5-min duration was the optimum treatment to overcome this dormancy. Once dormancy was broken, the Dalby biotype exhibited a greater germination (93%) compared with the St George biotype (87%). The nondormant seeds of both biotypes showed a neutral photoblastic response to light and dark conditions, with germination marginally improved (6%) under illumination. Maximum germination of both biotypes occurred under an alternating temperature regime of 30/20 and 35/25 C and under constant temperatures of 32 or 35 C, with no germination at 8 or 11 C. Seed germination of both biotypes decreased linearly from 87% to 14% with an increase in moisture stress from 0.0 to −0.8 MPa, with no germination possible at −1.0 MPa. There was a gradual decline in germination for both biotypes when imbibed in a range of salt solutions of 25 to 250 mM, with a 50% reduction in germination occurring at 150 mM. Both biotypes germinated well under a wide range of pH values (4.0 to 10.0), with maximum germination (94%) at pH 9.0. The greatest emergence rate of the Dalby (87%) and St George (78%) biotypes was recorded at a burial depth of 1.0 cm, with no emergence at 16.0 cm. Deep tillage seems to be the best management strategy to stopS. cannabina’s emergence and further infestation of cotton (Gossypium hirsutumL.) fields. The findings of this study will be helpful to cotton agronomists in devising effective, sustainable, and efficient integrated weed management strategies for the control ofS. cannabinain cotton cropping lands.

Germination Ecology of Brachiaria eruciformis in Australia and Its Implications for Weed Management

“…A burial depth of 4 cm and a sorghum residue amount of 4 t ha −1 reduced the emergence of B. eruciformis by 84% and 65%, respectively. Reductions in the emergence of weeds due to an increase in the burial depth and residue amount have been reported for numerous weeds [37][38][39]. The low emergence of B. eruciformis with the increase in the burial depth and sorghum residue amount could be attributed to low seed carbohydrate reserves, the light requirement [40,41], and could sometimes be due to allelopathy of the sorghum residue [42].…”

Germination of seven species of shrubs in semiarid central Mexico: Effect of drought and seed size

“…Germination was recorded daily for a period of one month, which is the recommended time for germination tests (Baskin & Baskin 1998). We considered a seed to have germinated when the emerged radicle reached ≥ 2 mm in length (Iqbal et al 2019).…”

Effect of Different Climate Change Variables on the Ecology and Management of Sesbania cannabina through Glyphosate

“…Sesbania cannabina (Retz.) Pers, a C3 annual Fabaceae shrub, is rapidly becoming a ubiquitous problematic weed in the dryland and irrigated cotton production regions of Australia [ 22 , 23 , 24 ]. It not only impacts cotton production, but heavy infestations also reduce lint yield substantially and deteriorate its quality, as well as interfering with harvesting operations [ 25 ].…”