Evaluation the Importance of Recovery Growth as A biological Selection Parameter for Wheat Genotypes under Rainfed Conditions.

A field trail was conducted during the two consecutive growing seasons 2008 / 2009 and 2009 / 2010, in order to assess the relevance of recovery growth as a biological selection parameter in determining the productive capacity of wheat genotypes under dry farming systems. The experiment was laid according to randomized complete block design (RCBD) with three replications. It has been found at the end of the recovery growth period that the plant height was significantly higher in the water-stressed plants (72.03 cm) compared with the non water-stressed ones (59.19 cm). Plant height was significantly higher in the bread wheat variety Douma2 (74.50 cm), while it was significantly lower in the varieties Safeet1, Cham3 and Kareem (57.97, 59.16 and 59.35 cm, respectively), without significant differences among them. The average fresh and dry weight was significantly higher during the first growing season (48.86 and 22.75 g, respectively), compared with second one (30.82 and 13.65 g respectively), and in the water-stressed plants (47.11 and 21.44 g, respectively), compared with the control (32.56 and 14.96 g respectively), and in the varieties Cham6, Douma2 and Cham4 (43.31, 42.72, 41.29 ; 21.14, 19.75 and 21.30 g, respectively) without significant differences among them, while the fresh weight was significantly lower in the varieties Barakha, Kareem, Safeet1 and Bohooth208 (32.31, 34.66, 38.09 and 39.31 g, respectively), and the dry weight was significantly lower in the varieties Kareem, Cham3 and Safeet1 (14.22, 14.68 and 16.67g, respectively). Water stress doubled the leaf proline content, and the proline content was significantly higher in the varieties Safeet7, Cham6, Cham4 and Cham3 (16.22, 16.17, 16.01 and 15.64 ug . g-1, fresh weight). The average grain yield was significantly higher during the second and first growing seasons, respectively, in the non stressed plants, in the bread wheat varieties Cham6, Bohooth208 and Douma2 (1077.0, 1005.0 and 989.2 g . m-2, respectively), while it was significantly lower during the second growing season in the water-stressed plants, in the varieties Douma2 and Safeet1 (351.3 and 353.0 g . m-2, respectively). In general, the wheat grain yield is highly determines by the number of grains per unit land area than 1000-kernel weight,and the recovery growth trait can be considered as one of the important bio-physiological traits only in the latematuring varieties, but it is not in the early-maturing ones, especially if drought shortens the different phonological phases.