174 V. G. Kakani et al.
pot studies. Model PNUTGRO was run to simulate the ASM in the irrigated and WS
treatments and presented in Fig. 8.6.
The simulations concur with soil water calculations and both confirm that the
soil moisture was around 60 % ASM at the end of high-temperature treatment. The
ASM averaged to 70 % from sowing to harvest in irrigated plots. In the case of WS
plots, ASM averaged to 40 % during the stress period, even though the plants expe-
rienced a severe stress of around 25 % towards harvest.
Controlled environment and field studies also suggest that when soil moisture is
around or less than 40 % ASM, critical for groundnut (Wright and Nageswara Rao
1994 ), water stress dominated the stress effects. Water is a reactant or substrate for
many reactions in plant (Kramer and Boyer 1995 ), and the rate at which these reac-
Fig. 8.5 Summary of the combined high temperature and water stress effects on growth and devel-
opment of groundnut in SAT. ( Thick arrows = main routes for assimilate translocation; Thin black
arrows = routes for minor use of assimilates; broken arrow = information flow; red arrow = tem-
perature effects; blue arrow = water stress effects; red and green arrow = interaction of tempera-
ture and genotype; blue and green arrow = interaction of water stress and genotype; WT weight;
Labile = current and stored assimalte pool). Direction of red/blue arrows opposite to assimilate
route indicates negative effects. Pod number ( PDNO); peg number ( PGNO); flower number
( FLNO); pod weight ( PODWT); root weight ( ROOTWT); stem weight ( STEMWT)