Genotypes selection and optimizing mineral nitrogen, phosphorus and potassium fertilization are important factors that influence flax growth, yield and quality. Two field experiments were conducted at the Experimental Research Station in Esmailia, Field Crops Research Institute, Agricultural Research Center, Egypt during the growing seasons of 2012/2013 and 2013/2014 seasons to study the effect of mineral nitrogen, phosphorus and potassium fertilization on yield and quality of some flax genotypes under sandy soils conditions. The experiments were carried out in a split-plot design with three replicates. The main-plots were assigned to flax genotypes (Giza 10, Sakha 2 and strain 22). The sub-plots were allocated to mineral fertilization treatments (fertilizing with mineral N, P, K, NPK and without mineral fertilization). The results indicated that significant differences among the three studied flax genotypes i.e. Giza 10, Sakha 2 and strain 22 were detected in all studied characters, except number of seeds/capsule in both seasons. Fertilizing flax plants with 75 kg N + 23.25 kg P2O5 + 24.0 K2O/fed significantly increased all studied characters and produced the highest values as compared with other studied mineral fertilization treatments in both seasons. Control treatment (without mineral fertilization) gave the lowest values of all studied characters. On the basis of the results obtained, maximum straw and seed yields and its components of flax could be achieved through fertilizing Strain 22 or Sakha 2 genotypes with 75 kg N + 23.25 kg P2O5 + 24.0% K2O/fed. However, maximum fiber flax yield resulted from fertilizing Giza 10 cultivar with 75 kg N + 23.25 kg P2O5 + 24.0 K2O/fed under sandy soils conditions in Esmailia Governorate.

Two field experiments were conducted at the Experimental Farm, Sakha Agric. Res. Station , Sakha, kafrelsheikh, Egypt during the two successive winter seasons of 2012/2013 and 2013/2014 to study the effect of four harvesting dates i.e 120,130,140 and 150 days after sowing and retting methods (Retting in water change every 24 hours and Still water retting) on yield and its quality yield components of three flax Genotypes (Sakha 3, Ilona and S. 541 /D/10) The experimental design was split plot with four replicates where in field experiment, the three genotypes were distributed in the main plots and harvesting dates were allocated in the sub plots, while after harvesting the twelve combinations between the genotypes and harvesting were distributed in the main plot while the two retting treatments were allocated in the sub plots. The results revealed high significant differences among the flax genotypes in straw yield and its components. Sakha 3 cultivar registered the greatest values of technical length, straw yield/plant and straw yield/fed., sakha 3 and Ilona cultivars gave the highest values in fiber strength, fiber fineness, fiber percent, fiber yield /plant and fiber yield /fed. while S. 541 /D/10 genotype was the highest in stem diameter, fruiting zone length, number of capsules/plant, number of seeds /plant, 1000-seed weight, seed yield / fed. and seed oil content. The results revealed that the harvesting flax plants at 140 DAS gave significantly increases in technical length and fruiting zone length in both seasons. While, the same effect was in seed yield /plant& straw yield /fed. in the second season and in both seed yield /fed. and straw yield/ plant in first season, on the other hand the traits of fiber length, fiber strength, fiber fineness, fiber percent, fiber yield /plant and fiber yield /fed. recorded the highest significantly values at harvesting date 140 DAS in both seasons and did not significantly differed with harvesting date 150 DAS in fiber length in both seasons and in fiber yield /fed. in the second seasons. However, delayed harvesting date to 150 DAS showed the highest values in number of capsules/plant, number of seed /plant, 1000-seed weight (g), seed yield /plant, seed yield /fed. straw yeild/fed. seed oil content in both seasons and straw yield/plant in the second season. While, The harvest date at 130 DAS recorded the highest values in stem diameter in both seasons compared with other harvesting dates. The interaction between the genotypes and harvesting dates had a significant effect in technical length, fiber strength, fiber fineness, fiber percent, fiber yield /plant, fiber yield /fed. fruiting zone length, stem diameter, number of capsules/plant, number of seed /plant, 1000-seed weight, seed yield /plant , seed yield /fed., straw yield/plant straw yield/fed. and seed oil content in both seasons. The twelve combinations between genotypes of flax and harvesting dates recorded significant differences in fiber fineness, fiber length, fiber strength, fiber percent, fiber yield /plant a...