Early Development of Johnsongrass

Abstract

Tillering, flowering, and rhizome formation of johnsongrass(Sorghum halepense(L.) Pers.) started approximately 2 months after planting seeds or single-node rhizome fragments in the warm season. The minimum temperature for rhizome formation was between 15 and 20 C. Inflorescences were produced only from May to November. No causal relationship was found between flowering and rhizome formation. The bud activity of new rhizomes, as assessed by sprouting of single-node fragments, ranged between 48 and 100%. Sprouting was nil at 10 C, slow below 20 C, and maximum at 28 C. Seed germination required a temperature about 10 C higher than rhizome sprouting. While the initial leaf production of seedlings was more rapid than on plants produced from rhizomes, other differences in growth and development between seedlings and rhizome plants were of only limited practical significance.

Prediction of Sorghum halepense (L.) Pers. rhizome sprout emergence in relation to air temperature

“…The data obtained in these experiments suggest that S. halepense rhizome sprout emergence rates can be predicted using accumulated thermal units based on air temperature. The model obtained agrees with evidence on the temperature requirements of rhizome buds given by laboratory experiments (Ingle & Rogers, 1961;Hull, 1970;Horowitz, 1972a) suggesting that the growth rate of rhizome buds depends very much on temperature at the beginning of the growing season but that later on it becomes less responsive to it. Given the nature of the process described by the model, some other factors might be considered under field conditions to be important in its regulation.…”

“…No bud germination was observed with rhizomes maintained below I5'C, but at 15 C bud sprouting begins and this increases with temperature up to 28 C (Hull. 1970;Ingle & Rogers, 1961;Horowitz, 1972a).…”

Below‐ and above‐ground growth and biomass allocation in maize and Sorghum halepense in response to soil water competition

“…The rhizomes were trimmed to pieces with two nodes, weighing from 5 to 8 g. All propagules were washed free of soil and then soaked in a solution of 0.30 g L −1 benomyl (methyl 1‐[butylcarbamoyl]‐2‐benzimidazolecarbamate) (Iperlate WP; Ipesa) for 10 min to reduce decay. Rhizomes were then layered in moist vermiculite and held in a growth chamber at 28°C (Horowitz, 1972). Four sprouted buds per pot were planted simultaneously with maize hybrids on 5 October 2003 and 8 October 2004.…”

The biology of Johnson grass (Sorghum halepense)

“…The pattern of growth and development of Johnson grass seedlings and rhizome sprouts is similar (McWhorter, 1961;Horowitz, 1972a), although in the field rhizome sprouts are thought to emerge earlier and to grow more rapidly than seedlings (McWhorter, 1961), Three weeks after emergence of seedlings and sprouts, a rhizome spur is formed and secondary tillers are initiated. Leaf growth is slow during this period.…”