Defoliation Effects on Grain Fill, Stalk Rot, and Lodging of Grain Sorghum

Abstract

Yield response to defoliation in grain sorghum [Sorghum bicolor (L.) Moench] can be influenced by time and intensity of leaf removal. Limited information is available for defoliation ✕ environment interactions and the defoliation response of yield‐related traits, stalk rot, and basal stalk lodging. This study was conducted to examine the effect of time and extent of defoliation on hybrid grain sorghum in three eastern Nebraska environments in relation to yield components, duration and rate of grain filling, nonsenescence period, stalk rot, and lodging. Four levels of defoliation (0, SO, 95, and 100%) were applied to plants at 10 d preanthesis, anthesis, 10 d post anthesis, and 20 d post anthesis. Defoliation significantly decreased yield components, grain‐fill duration, grain‐fill rate, and the nonsenescence period, while increasing the occurrence of stalk rot. The most pronounced effects on all traits occurred when plants were defoliated prior to or during anthesis. Significant defoliation level ✕ time interactions and environment ✕ defoliation treatment interactions were observed for all traits. Variance component estimates indicated that environmental interaction comprised 18 to 25% of total variation for the yield components, 5% for stalk rot, and 50% for lodging. Use of defoliation in a limited number of environments may not prove effective in evaluating tolerance to lodging. Small environmental interactions for the stalk rot response suggest that observations from only a few environments are necessary for its evaluation.

Physiological mechanisms of drought tolerance in sorghum, genetic basis and breeding methods: A review

“…Genetically, male sterile plants showed a twofold increase in assimilate storage in the stems, indicating that removal of a grain sink increases stem sugar (Fortmeier and Schubert, 1995). Leaf defoliation during anthesis promoted lodging, suggesting that it may be due to depletion of carbohydrates from the stem (Rajewski and Francis, 1991). Conversely, each plant sink events (plant height, flowering time and tillering) may increase sugar production potential in nonstress environments (Murray et al, 2008).…”

Sorghum RILs Segregating for Stay‐Green QTL and Leaf Dhurrin Content Show Differential Reaction to Stalk Rot Diseases

“…Fourteen genotypic groups derived from the Tx642  Tx7000 recombinant inbred line (RIL) population carrying a combination stg QTL were evaluated under three environments in four replications. High levels of sugar in the stem were also reported to reduce the incidence of stalk and root rot diseases caused by M. phaseolina (Clark and Miller, 1980;Hiremath and Parvatikar, 1985;Rajewski and Francis, 1991). Genotypes carrying either stg1 or stg3, or their combination stg1+3 expressed high levels of resistance to M. phaseolina.…”

Carbon Integration in Plantago aristata (Plantaginaceae): The Reproductive Effects of Defoliation

“…Therefore, if we had chosen to defoliate our experimental plants only at onset of flowering, or later, we would have erroneously concluded that seed size showed a greater response to defoliation. Agricultural studies have also shown that delaying the time of stress relative to floral and fruit development decreases the negative effect on fruit and seed number but increasingly depresses seed weight (e.g., Sharrow, 1990;Rajewski and Francis, 1991).…”