Tiller mortality and its relationship to grain yield in spring wheat

A primary determinant of grain yield in barley (Hordeum vulgare L. emm. Lam) is the number of ear-bearing tillers per plant at harvest, which depends

both on the production of tillers and on their subsequent survival to form ears. This three-year field study compares tiller production and survival in

relation to final grain yield in three types of barley: 2-rowed winter (2rw), 6-rowed winter (6rw) and 2-rowed spring (2rs), grown in two contrasting

environments. These three types differed significantly in shoot and ear number, the winter barleys showing higher tiller production, with the maximum number of tillers ranging from 798 to 2315 m−2 in 2rw, 711

to 1527 in 6rw and 605 to 1190 in 2rs. Grain yield across environments and years was strongly correlated () with the number of ears at harvest. The maximum

number of shoots produced by each type of barley was inversely related to the mean temperature during the tillering phase. Tiller mortality was inversely

related to the maximum shoot production, being significantly lower in barleys with less tillering capacity, i.e. the spring type (with average values of

34.3% and 42.7% in the two environments). The highest tiller mortality occurred before anthesis and, to a lesser extent, from anthesis to maturity. These

data support the hypothesis that the principal cause for tiller mortality in barley grown under Mediterranean conditions is the competition between tillers

for a limited supply of resources.

Spikeless tillers of wheat (Triticum aestivum L.) affect grain yield because of less than optimum effective plant population. This study was conducted to

examine the genetic variability for tiller mortality, and its relationship to grain yield in diverse wheat lines. Twenty lines were evaluated in replicated

field tests in 4 years at Rampur, Nepal. The characters investigated were maximum number of tiller produced, the number of reproductive tillers, tiller

mortality, and grain yield. The lines differed significantly for all characters. The tiller mortality ranged from 7 to 30%. There were substantial effects of

environment on all four characters.