M. Benbella et Gm. Paulsen, EFFICACY OF TREATMENTS FOR DELAYING SENESCENCE OF WHEAT LEAVES - I - SENESCENCE UNDER CONTROLLED CONDITIONS, Agronomy journal, 90(3), 1998, pp. 329-332
Senescence of wheat (Triticum aestivum L,) leaves is accelerated by hi
gh temperature during the critical grain filling period. Loss of Leaf
viability decreases grain yields and the response to production inputs
. Studies were conducted under controlled conditions to identify treat
ments that might delay the rapid senescence induced by high temperatur
e. Shoots of 30-d-old seedlings of 'Nesma' wheat were immersed in 0.1
mill solutions of kinetin, abscisic acid, or one of six mineral salts
[0.1 mM Ca(NO3)(2), NaH2O4, K2SO4, KH2PO4, KNO3, or NH4H2PO4] and incu
bated at 20 and 30 degrees C with continuous irradiance of 150 mu mol
m(-2) s(-1). Chlorophyll and free amino acid concentrations and crude
protease enzyme activity were monitored over an 8-d period as measures
of shoot senescence. High temperature and abscisic acid generally inc
reased all senescence processes, whereas kinetin and several mineral s
alts reduced the loss of chlorophyll and slow-ed the increases in amin
o acid concentration and protease activity compared with amounts in sh
oots incubated in distilled water, Mineral salts that contained N or P
were usually most effective, particularly in countering rapid senesce
nce at 30 degrees C relative to 20 degrees C. We conclude that senesce
nce processes induced by high temperatures in detached shoots resemble
those in whole plants and that the feasibility of delaying senescence
by foliar application of selected compounds under field conditions me
rits investigation.