Effect of Soil Temperature and Depth of Planting on the Emergence and Development of Sorghum Seedlings in the Greenhouse<sup>1</sup>

203

Research with grain sorghum often involves sampling several times during the growth cycle. Samplings often are designated by calendar date, days after planting or emergence, or plant height. Often these bear little or no actual relationship to the morphological or physiological age or status of the plant. Although certain stages of sorghum growth are fairly well established, the growth cycle of sorghum has not been fully described. Therefore, a standard set of growth stages needs to be defined. Based on detailed studies of grain sorghum hybrids of different maturities, the following ten stages of development have been defined and illustrated: emergence, three‐leaf, five‐leaf, growing‐point, differentiation, final leaf visible in whorl, boot, half‐bloom, soft dough, hard dough, and physiological maturity. These stages are suggested as standards to describe the timing of sampling or treating sorghum.

Section: --------------------mentioning

confidence: 99%

“…This occurs approximately 10 days after emergence, however, time required to reach stage I can vary widely with environmental conditions. For counting leaves Martin et al, (6) found II days post emergence at 30 C to U days at 15 C were required to reach the 4-leaf stage. , Stage 2.…”

Section: --------------------mentioning

confidence: 99%

Growth Stages of Sorghum [Sorghum bicolor, (L.) Moench.]¹

Vanderlip¹,

Reeves

1972

203

“…Coffman (2) showed that corn germinated best at temperatures above lOC, with a sharp decrease in germination below 1 OC. Martin et al (6) found that the percentage and rate of germination for several varieties of sorghum were reduced by soil temperatures below 25C. Cummins and Parks (3) Teported corn did not germinate at 1 OC.…”

Section: --------------------mentioning

confidence: 99%

Corn Emergence in Relation to Soil Temperature and Seeding Depth¹

Alessi¹,

Power²

1971

Field and growth room experiments at Mandan, N. D., evaluated the effects of seed depth and soil temperature on corn (Zea mays L.) germination and emergence. In the growth room, from 4 to 24 days were required to achieve 80% emergence, depending upon soil temperature and seed depth. Increasing soil temperature from 13.3 to 26.7 C reduced the time for 80% emergence. Temperature had a much greater effect than seed depth on emergence. A highly significant linear relationship existed between percent emergence and cumulative degree‐days above 10 C. In field treatments with adequate soil water for germination, 8 to 13 days were required for near 80% germination. About one additional day was required for each 2.5‐cm increase in depth of planting. For corn placed at 7.6 cm, about 10 days and 68 cumulative degree‐days were required for emergence. Similar degree‐day requirements occurred for the 12.7‐cm depth. Degree‐day requirements for field experiments agreed very well with those obtained in the growth room.

“…Total germination of sorghum was unaffected, but the rate was slowed, when temperature was reduced from 26.7 to 16.7 °C. Martin et al (1935) reported that both the percentage and rate of germination in sorghum was reduced by soil temperatures below 25 oc. Germination of five forage-type pearl millet cultivars was reduced when the OP in-•creased from 0.3 to 0.8 MPa (Fanous, 1967).…”

mentioning

confidence: 99%

Water Stress and Temperature in Relation to Seed Germination of Pearl Millet and Sorghum

Smith

Hoveland²,

Hanna

1989

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a potentially productive high‐quality grain crop that appears superior to sorghum (Sorghum bicolor L. Moench) in establishment under limited soil moisture. Our objectives were to compare sorghum and pearl millet seed germination under moisture stress conditions at two temperatures. Drought resistance was tested by germinating seeds in polyethylene glycol solutions with osmotic pressures of 0, 0.4, 0.8, and 1.2 MPa at 15 and 30 °C. At both temperatures pearl millet germination was less affected by increasing osmotic pressure (OP) than sorghum germination. At 30 °C sorghum germination decreased steadily as OP increased above 0 while pearl millet germination decreased significantly above an OP of 0.8 MPa. At 15 °C, pearl millet germination was always significantly higher than sorghum germination although the germination of both decreased steadily as OP increased. No germination occurred in either species at an OP of 1.2 MPa at 15 °C. The median germination time (MGT) at 30 °C for pearl millet was less than the MGT of sorghum under osmotic stress. There were no differences between sorghum and pearl millet MGT at 15 °C except at an OP of 0.4 MPa. The average MGT was higher at 15 °C than at 30 °C. Median germination time increased with each rise in OP, except for pearl millet between osmotic pressures of 0 and 0.4 MPa at 30 °C. The results indicate that pearl millet seed germinates better than sorghum seed under drought and lower temperature. The ability to germinate under stressful conditions could give pearl millet an advantage in stand establishment under the less than ideal conditions that frequently occur in the field.