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Foster, M., G. Kleine, and J. Moore. 1993. Impact of seeding rate and planting date on guayule stand establishment by direct seeding in West Texas. p. 354-355. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New York.

Impact of Seeding Rate and Planting Date on Guayule Stand Establishment by Direct Seeding in West Texas

Michael Foster, Greg Kleine, and Jaroy Moore

  1. METHODOLOGY
  2. RESULTS AND DISCUSSION
  3. CONCLUSIONS
  4. REFERENCES
  5. Fig. 1
Transplanting of greenhouse-grown seedlings has been the only reliable method of guayule stand establishment. Bucks et al. (1986) estimated that development of direct seeding methods could reduce the cost of establishment to below $400/ha versus $900 to $1,200/ha for transplanting. Recently, Foster et al. (1991) calculated that the cost of establishment could be reduced to $250/ha or less.

Foster and Moore (1991) demonstrated that guayule stand establishment was possible with conditioned seed and precision planting. Seeding rate and the optimum date of planting still must be defined throughout the potential guayule production region. The objectives of this study were to examine the effects of seeding rate and planting date on guayule stand establishment by direct seeding in west Texas.

METHODOLOGY

The study was conducted during 1991 at the Texas Agricultural Experiment Station Guayule Research Site near Fort Stockton. A split plot design arranged in a randomized complete block with four replications was used with date of planting (31 May, 28 June, 15 Aug., and 1 Oct.) and seeding rate (30, 40, 50, 60, 80, 100 seeds/m) as main and subplots, respectively. Main plots were 6 m wide (six 1 m wide rows) and 9 m long. Subplots consisted of single rows 9 m long seeded with a Gaspardo SV 255 pneumatic planter. Mexican bulk guayule seed was conditioned by the process outlined by Chandra and Bucks (1986). Seed germination was 80%. Seedling density (Fig. 1) was not adjusted for percentage germination. The plots were sprinkler irrigated and kept moist during germination and emergence.

RESULTS AND DISCUSSION

Initial germination and emergence was greatest in August (Fig. 1). Seedling density was consistently greater in the 80 and 100 seeds/m treatments as compared to the lower seeding rates. Based on plant spacing recommendations for transplants, 2 to 3 established seedlings/m would be required for an acceptable stand (27,500/ha or 11,500/acre). Even the lower seeding rates (30 to 60 seeds/m) satisfied these requirements. Seeding rate may need to be adjusted for seed quality (% germination), weather factors (heavy rain and hail), insect damage to young seedlings, and reduced germination by preemergence herbicides. Therefore, rates of 40 or 50 seeds/m may be more realistic, and would require 0.22 to 0.30 kg of seed/ha (0.20 to 0.22 lb./A). Initial seed quality can affect the germination rate of conditioned seed.

Just after plant emergence, the May seeding was damaged by heavy rain and hail, which can occur throughout the growing season. Seedlings in the cotyledon stage were damaged by fall armyworms (Spodoptera frugiperda) in the July study.

CONCLUSIONS

Direct seeding guayule during 1991 in west Texas was successful in May, June, and August. Seedling density was greatest in the 100 and 80 seeds/m treatments. Based on plant population recommendations for guayule transplants, even lower seeding rates (30 to 60 seeds/m) were acceptable for stand establishment. Seeding rates of 40 to 50 seeds/m may be more realistic and should be adjusted for seed quality, weather factors, insect damage to young seedlings, and possible reduced germination by preemergence herbicides.

REFERENCES

Fig. 1. Average number of guayule seedlings/m row in plots planted at 100, 80, 60, 50, 40, and 30 seeds/m.
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