Spikelet development and grain yield of the wheat ear in response to applied nitrogen

Abstract

Wheat plants in an irrigated field crop were fertilized with 0 (N0), 3 (N3), 10 (N10) or 30 (N30) kg nitrogen ha-1 week-1 for 10 weeks, commencing 12 days after sowing, till the flag leaf reached maturity. Nitrogen significantly increased tiller numbers, dry matter and grain yields per plant. Maximum plant size resulted from the N30 treatment, but maximum grain yields per plant from the N10 treatment. Total spikelet numbers increased with increasing nitrogen supply up to the N30 treatment, and this was due to increased rates of spikelet primordia production. Nitrogen treatments had almost no effect on the duration of spikelet primordium formation. Only two ear-bearing tillers were produced in the N10 and N30 treatments, and none in the others. Tiller apices had a similar, or in the case of the second tiller of N30 plants a 29% higher, rate of spikelet primordia formation to that of the associated main shoot, and all apices formed terminal spikelets at a similar time. The second tiller did not initiate primordia production until 25% of final spikelet numbers were present on the main shoot apex. The higher grain yield per plant in the N10 than in the N30 treatment was due largely to more grains per fertile spikelet on the tillers of N10 plants. It was speculated that the poorer performance of tillers on N30 plants was due to mutual shading of shoots and/or poorer nitrogen nutrition of the tiller apices owing to the method of nitrogen application. It was concluded that nitrogen supply affected grain yield per ear more by influencing the ability of florets to set grain than by varying spikelet number.

Nitrogen fertilization for wheat growing in dual purpose integrated system of agricultural production

“…Nitrogen fertilization changed the spike length (P = 0.0017), showing that there was a growth of ears, but not fertile flowers, diverging from the results reported by Whingwiri and Kemp (1980), that the application of nitrogen in one dose was held in the period spikelet terminal resulting in a greater number of fertile flowers (flowers that will establish grains) and consequently high yield.…”

Initiation and Development of Spikelets and Florets in Wheat as Influenced by Shading and Nitrogen Supply at the Spikelet Phase

“…Nitrogen deficiency decreases the rate of primordium initiation, resulting in fewer spikelets, and delayed time of the DR and TS stages (Longnecker et al, 1993;Whingwiri and Kemp, 1980). However, the literature contains conflicting results about the effect of nitrogen supply at the DR stage on the number of spikelets.…”

“…Some other experiments showed that high N regimens before floral initiation increased spikelet number, but generally do not affect the time of spike development (Baker and Gallagher, 1983a;Ewert and Honermeier, 1999;Frank and Bauer, 1982;Nerson et a!., 1990;Peltonen, 1992Peltonen, , 1993Whingwiri and Kemp, 1980). Nitrogen deficiency decreases the rate of primordium initiation, resulting in fewer spikelets, and delayed time of the DR and TS stages (Longnecker et al, 1993;Whingwiri and Kemp, 1980).…”

Effect of nitrogen fertilizer application timing on nitrogen use efficiency and grain yield of winter wheat in Ireland

“…Grain yield in wheat is better related to grain number per unit area than to individual grain weight (Slafer and Andrade, 1989). Nitrogen deficiency during the stem elongation phase is more likely to result in reduced GPE by reducing spikelet number or by increasing floret abortion (Langer and Liew, 1973;Whingwiri and Kemp, 1980;McMaster, 1997). There was some evidence that this occurred in 2011 considering that the GPE was reduced when the first application of N fertilizer was withheld until GS 37.…”