A study of dry matter partitioning and concentration in grain Amaranth (Amaranthus cruentus)

Dry matter partitioning and dry matter concentration were studied for nine weeks in potted grain amaranth (Amaranthus cruentus) grown under three levels, respectively, of water and NPK fertilizer applications.The water applications were to 100, 75 and 50% of field capacity.Those of fertilizer were 100, 75 and 50 % of 90 kg/ha.Field samples were collected at weekly intervals from the 4th week for the fresh and dry weights analysis of shoot and root.Dry matter concentration was estimated on weight basis as percentage of dry matter in fresh matter.Dry matter concentration and percentage dry matter partitioning to shoot components and to root varied throughout the period of study in all the treatment combinations.Generally, the highest percentage dry matter partitioning to the root was in Week 7 with an average value of 36.6 % for all the treatment combinations.For the leaves the highest values occurred between Weeks 4 and 5 and averaged 65.6 % for all the treatment combinations.For stem plus branches and inflorescence, the highest percentages were observed in Week 9 and averaged 46.5 % and 6.3 % respectively.Dry matter concentration was highest in Week 9 for root, stem plus branches and inflorescence with average values of 25.5, 25.0 and 15.3 % respectively.For the leaves the highest dry matter concentration occurred in Week 8 and averaged 20.5 % for all the treatment combinations.An analysis of variance showed that elapsed time after planting and water application were the main factors affecting dry matter partitioning and dry matter concentration.Fertilizer application had no significant effect.However, fertilizer interaction with time significantly affected dry matter concentration in the roots.