Nitrogen Fertilizer Effects on Growth, Flowering, Oil Yield, and Yield Components in Meadowfoam¹

Abstract

Meadowfoam (Limnanthes alba Benth.) seed is a source of oil for use in industrial products and processes. Nitrogen fertilization typically has not increased seed yields of meadowfoam. Data are lacking for characterizing plant growth responses, flowering, honey bee (Apis mellifera L.) foraging, oil yield, and yield components of meadowfoam when fertilized with N. Thus, this field study was conducted in 1981 and 1982 on a Woodburn silt loam soil (fine-silty, mixed, mesic Aquultic Argixeroll) to determine the effects of ammonium sulfate applied at 0 (control), 50 (SON), and 100 (lOON) kg N ha-•. Increased vegetative growth of meadowfoam in response to spring application of N appears to be consistent. Nitrogen fertilization lowered canopy light transmittance and caused a differential flowering response from nonfertilized plants. Seeds per flower in the N-fertilized treatments were not increased. Flower densities inN-fertilized treatments in 1982 averaged 135% higher than in the control. Seed yields were not increased by N in 1981, but in 1982, seed and oil yields were increased by 113 and 99%, respectively, when N was applied. Oil content was consistently lower when N was applied, but this effect was more than offset by the higher seed yield in 1982. Because of the similar response of agronomic characters in SON and lOON treatments, applications of 100 kg N ha-• do not appear to be advantageous. Spring N fertilization of meadowfoam increased seed yield primarily through increased flower number.

Evaluating Nitrogen Fertilizer Rate and Timing for Meadowfoam Seed and Dry Matter Production

“…The effects of N fertilizer on Mermaid dry matter production are apparently consistent, although the degree of this response may vary from year to year. This agrees with Pearson and Jolliff (1986) who reported that under the same N fertilizer treatment meadowfoam produced 50% more dry matter and grew 40% taller during the 1st yr of their experiment compared to the second year. The increase in seed yield with the application of 50 kg N ha-1 in late winter or early spring is also consistent with that reported by other researchers working with Mermaid Young, 1985, 1986;Pearson and Jolliff, 1986).…”

“…This agrees with Pearson and Jolliff (1986) who reported that under the same N fertilizer treatment meadowfoam produced 50% more dry matter and grew 40% taller during the 1st yr of their experiment compared to the second year. The increase in seed yield with the application of 50 kg N ha-1 in late winter or early spring is also consistent with that reported by other researchers working with Mermaid Young, 1985, 1986;Pearson and Jolliff, 1986). However, the increase in seed yield with the application of up to 200 kg N ha-1 observed in the 1984-85 season should be interpreted with caution.…”

“…However, the increase in seed yield with the application of up to 200 kg N ha-1 observed in the 1984-85 season should be interpreted with caution. Treatments receiving 200 kg N ha-1 produced only 6530 kg ha-1 dry matter during that season, compared to more than I 0 000 kg ha-1 dry matter reported for plots receiving only 50 kg N ha-1 in previous studies (Pearson and Jolliff, 1986). No lodging was observed, and the highest meadowfoam seed yield and harvest index on record was measured during that season.…”

“…Excessive rainfall during flowering, and subsequent lodging, were apparently the causes for the lack of response in 1981 which resulted in an interaction between N application X year for seed yield. Pearson and Jolliff (1986) further concluded that application of 100 kg N ha-1 in March was not advantageous to 50 kg N ha-1 for seed production. More recently, Hart and Young (1985) also found that, except when meadowfoam followed a clover crop, spring application of 56 kg N ha-1 increased Mermaid seed yield.…”

“…The interactions of year X entry, year X rate, and time X rate X year were also significant for seed yield. Pearson and Jolliff ( 1986) studied the effects of N fertilization on a meadowfoam line which was later released as Mermaid. They reported a significant increase in seed yield with the application of 50 and 100 kg N ha-1 in March of 1980, whereas N application treatments had no effect on seed yield in 1981.…”