Vergara - 1976 - Physiological and morphological adaptability of ri

“tartan DEFICITS m (TERFAI. GRAINS 325
For forage crops, of course, the rate of leaf production is of considerable
economic importance, and it would be of interest if their drought response could
be modified. Singh ct al. (1973) have reported that gibberellic acid partially
reversed (by about one third) the effect of drought on wheat leaf growth.
Further experiments of this sort should be WOIlZlIVVlIllC.
In addition Io inhibitory effects on growth. however. an additional characteristic
of cereal crops is the tendency for their leaves to senesce during sustained
drought. This usually occurs during drought that is moderate to severe. An
example is shown in Fig. 2 and 3. which describe an experiment in which
Lnufwcllr pollntldfllcls)
o I I | | I l I I I
-22 | | | | | | | | |
O 6 l2 l8 24 3O 3S 42 4B 54 6O
Ttnwldup inc: mu of daniccutlat)
2. Leaf water potentials in maize desiccated during the grain filling period. The
plants were growing in soil in a controlled environment room at the Climatic
Laboratory at Palmerston North. _\'e\v Zealand. Desiccation was initiated by
withholding water from half the plants nine days after maximum pollen shed.
Therealler. the desiccated plants received a small amount of water [ 1-’? that of the
control]. which maintained leaf water potentials at — l9 to e 21 bars for the
remainder of the grain filling period.
Total teat one ("12, at‘ lfilllfll)
I l I I I
0 s l2 la 24 3o 36 42 4a 5460
Tlmllduw slnol start of desiccation)
3. Loss of leaf area due to senescence during grain fill in the maize described in
Fig. 2. The desiccated plants lost leaf area much more rapidly than those plants
that remained well watered. Senescence in the desiccated plants progressed
front the bottom of the plants upward. The reverse was observed in the control.