Supplemental foliar applied mixture of amino acids and seaweed extract improved vegetative growth, yield and quality of citrus fruit

Poor tree nutrient management significantly reduce productivity and quality of citrus fruit. Hence in three separate experiments, exogenous supplemental application of 0.5 mL L⁻¹ ‘Primo’ (Ascophylum nodosum seaweed extract + amino acid and) + 0.01% ‘Tween 20′) was sprayed on citrus cvs. ‘Kinnow’, ‘Feutrell's Early’ mandarins and ‘Blood Red’ orange trees. Trees were sprayed at full bloom (T2), fruit setting (T3), full bloom + fruit setting (T4), or full bloom + fruit setting + premature (T5) stages at a same concentration. Unsprayed trees of each cvs. were kept as control (T1). In contrast to untreated control trees, the application of 0.05% Primo at full bloom + fruit setting stage caused significant increase in leaf N (28%), K (36%), Mn (24.4%), Zn (15.8%), tree height (28.5%), fruit weight tree⁻¹ (42.6%), fruits tree⁻¹ (28.6%), marketable fruit (9%), fruit size (11.5%), SSC (16%), SSC:TA ratio (26.8%), reducing sugars (37.5%), ascorbic acid (21.8%) and total phenolic contents (42%) in ‘Kinnow’ mandarins. Likewise, sprayed trees of ‘Feutrell's Early’ in T₄ exhibits higher leaf N (27%), Fe (11.9%), Zn (26.4%), fruit weight tree⁻¹ (28.5%), fruits tree⁻¹ (40%), marketable fruit (12.7%), fruit size (15.9%), juice weight percentage (17.6%), taste (23%), SSC (15.7%) and total sugars (42%). Whereas, in case of ‘Blood Red’ oranges, same treatment (T4) resulted in highest level of leaf N (50%), Fe (15%), tree height (37%), leaf size (38.8%), fruit weight tree⁻¹ (42%), number of fruits tree⁻¹ (45%), marketable fruit (8%), juice weight percentage (15.6%), SSC (19%), SSC:TA ratio (43.8%), reducing sugars (45%) and total phenolic contents (28%) than control. In addition, reduction in fruit drop, peel thickness and TA were also observed in treated trees of all cvs. as compared to untreated control. In conclusion, supplemental application of 0.5 mL L⁻¹ ‘Primo’ at full bloom + fruit setting stages improved vegetative growth, productivity and quality of ‘Kinnow’, ‘Feutrell's Early’ and ‘Blood Red’ fruits.