To compare the wheat genotypes in terms of seed germination and growth of seedling under osmotic stress conditions, a laboratory experiment was conducted using a completely random design with factorial arrangement. The wheat genotype (G) consisted of eight genotypes numbered as (G1) 9103, (G2) 9116, (G3) 9203, (G4) 9205, (G5) 9207, (G6) 9212, (G7) C-81-10 and (G8) cross-shahi. The osmotic potential factor (Ψs) consisted of five levels (-1.2,-0.9,-0.6,-0.3 and 0 MPa). Genotypes G2, G6 and G7 prevailed in terms of germination percentage (GP) up to Ψs = -1.2, while genotype G8 and genotype G6 were only prevalent at Ψs = 0 and up to Ψs = -0.9, respectively. The two genotypes of G1 and G4 had lower GPs at Ψs = 0 compared to other genotypes but these two genotypes had no significant difference with resistant genotype G7 in terms of GP at Ψs = -0.3. This trend continued in case of genotype G1 up to Ψs = -1.2, while genotype G4 had the lowest GP value next to G8 cultivar from Ψs = -0.6 to Ψs = -1.2. Interaction effect of Ψs x genotype was significant for Coleoptile Length (CL), Radicle Length (RL), Plumule Length (SL). G7 prevailed in terms of CL with a significant difference at Ψs = -1.2 while G1 lost its dominance. The same trend was observed in interaction effect of Ψs x genotype for SL. According to GP and CL and SL values, modern genotype G7 was the most resistant genotype to osmotic stress while old genotype G8 was the most sensitive one.

El estudio tuvo como objetivo comparar, bajo condiciones de laboratorio, la germinación de semillas y el crecimiento de plántulas bajo condiciones de estrés osmótico de distintos genotipos de trigo. El diseño experimental fue de bloques completamente al azar con arreglo factorial y tres repeticiones. Se evaluaron ocho genotipos de trigo (G): 9103 (G1); 9116 (G2); 9203 (G3); 9205 (G4); 9207 (G5); 9212 (G6); C-81-10 (G7) y, cross-shahi (G8). El potencial osmótico ( Ψs) fue evaluado en cinco niveles (-1,2, -0,9, -0,6, -0,3 y 0 MPa). Los genotipos G2, G6 y G7 obtuvieron un mayor porcentaje de germinación (PG) a -1,2 MPa. Los genotipos G1, G4 y G5 tuvieron el menor porcentaje de germinación con Ψs = 0. El efecto de la interacción de Ψs x genotipo fue estadísticamente significativa para longitud de coleóptilo (CL), longitud de radícula (RL) y longitud de la plúmula (SL), según genotipo. De acuerdo con los análisis de resultados el genotipo G7 fue el más resistente al estrés osmótico y G8 fue el genotipo más sensible.

A retranslocação de reservas do colmo e espiga foi investigada com relação às restrições de fonte e dreno em plantas submetidas à deficiência de água e nitrogênio durante o enchimento de grãos. A fotossíntese e a sua contribuição para a produtividade foram reduzidas por ambas restrições. As restrições na fonte aumentaram a contribuição das reservas do colmo e da espiga. A maior mobilização de fonte sob restrição versus o controle e o dreno sob restrição indica que, no período de maior enchimento, a matéria seca do colmo foi reduzida por fornecer os assimilados após a restrição. Nas espigas reduzidas, a produtividade foi afetada pelo estresse hídrico indicando que após a antese o estresse pode aumentar a limitação por causa de taxas mais altas de enchimento e translocação de matéria seca duas semanas após a antese. Nas espigas reduzidas, o maior fornecimento de nitrogênio durante a antese elevou a produtividade porque maior translocação de matéria seca não está associada à maior fotossíntese. O nível mais alto de nitrogênio não foi capaz de aumentar a translocação quando todas as folhas, exceto a bandeira, foram removidas. Isso demonstra que o fornecimento de nitrogênio, após a antese, aumenta a produtividade por reduzir a limitação do dreno e não por aumentar a força da fonte.

Re-translocation of stem and spike reserves was investigated in source:sink restricted wheat subjected to water and nitrogen deficiency during seed filling. Either sink or source restriction significantly decreased the amount of current photosynthesis and its contribution to grain yield. Furthermore, source limitation increased stem and spike reserves contribution to seed filling process. Higher amount of stem reserve mobilization in source restricted vs. control and sink restricted plants indicates that at rapid grain filling stage (14 days after anthesis to physiological maturity), stem dry matter decreases to provide assimilates for kernel after defoliation. In spike halved plants, drought stress significantly decreased grain yield, indicating that when the sink is restricted, postanthesis drought stress can increase sink limitation through lower grain filling rate and dry matter allocation to grain two weeks after anthesis at the beginning of rapid grain filling stage. On the other hand, in spike halved plants, more nitrogen supply at anthesis increased grain yield because more dry matter allocation to grain is not associated with more current photosynthesis. But when all the leaves were removed except flag leaf, more postanthesis nitrogen could not increase dry matter allocation to grain filling process, showing that postanthesis nitrogen supply increases grain yield by decreasing sink limitation, and not by increasing source strength.