As to the root contents of free proline, coconut plants showed a maximum value of 6.58 [micro]mol [g.sup.-1] DM, at the water deficit level equivalent to 20% ETpc, while the treatment in which water requirements were fully met (100% ETpc) led to the lowest value of this variable (1.23 [micro]mol [g.sup.-1] DM).
The data best fitted to a decreasing linear equation ([R.sup.2] = 0.96), with a reduction of 0.0669 [micro]mol of free proline [g.sup.-1] DM, corresponding to 0.85%, per unit increase in the level of ETpc replacement (Figure 2B).
Contents of soluble carbohydrates in leaves ([SC.sub.leaf]) of seedlings of coconut palm as a function of water deficit levels (% ETpc)
Contents of free proline in leaves--[Pro.sub.leaf] (A) and roots--[Pro.sub.root] (B) of seedlings of coconut palm as a function of different water deficit levels (% ETpc)
For variable leaf area, it was estimated that the level of water replacement that provides maximum value for this variable (0.3428 [m.sup.2] per plant) is 100% ETpc associated to salinity of 1.72 dS [m.sup.-1].
Furthermore, under suitable water supply conditions, this effect was lessened, considering that for electrical conductivity of 40.70 dS [m.sup.-1], the leaf area measured under condition of 100% ETpc showed higher value of approximately 74% when compared to that obtained under severe water stress conditions (20% ETpc).
However, the lower leaf area of plants grown under the mutual influence of 100% ETpc and EC = 40.70 dS [m.sup.-1] compared to association of 100% ETpc and EC = 1.72 dS [m.sup.-1] ratifies the effect of salt concentration, to the point of restricting the magnitude of variable response regarding to water supply, again highlighting the significant effect of soil salinity on this variable.
For variable root dry biomass, Figure 1b and Table 4 showed positive and significant linear effects for ETpc and EC factors, with estimated increases of 0.0186 and 0.0102 g [plant.sup.-1], for each respective unit increment in the above factors, and the interaction between them also resulted in positive linear effects, with contribution of 0.0008 g [plant.sup.-1], also due to increases in combined factors.
Irrigation management with moderate water deficit, 50% ETpc, in the vegetative stage, promoted the best agronomic characteristics and contributed to increase the yield of the evaluated soybean cultivars, especially M9144RR.
Description of the treatments in the plots Treatment Description T1 Crop under water deficit along the entire cycle, irrigated with 25% ETpc T2 Crop under water deficit along the entire cycle, irrigated with 50% ETpc T3 Crop under no water deficit, irrigated with 100% ETpc T4 Crop under water deficit of 25% ETpc during the vegetative stage, beginning the differentiation in V1 T5 Crop under water deficit of 50% ETpc during the vegetative stage, beginning the differentiation in V1 T6 Crop under water deficit of 25% ETpc during the reproductive stage, beginning the differentiation in R1 T7 Crop under water deficit of 50% ETpc during the reproductive stage, beginning the differentiation in R1 Table 3.