Recovery from autotoxicity in strawberry by supplementation of amino acids

Supplementation of amino acids was investigated in recovering growth and yield of strawberry plants under autotoxicity developed in closed hydroponic systems. In greenhouse setting, a total of twenty two water soluble amino acids were sprayed on strawberry plants at 2 mL per plant three times a week. The concentrations of all amino acids were adjusted to nitrogen content of Proline at 200 mg L−1. It was found that growth and yield of strawberry plants grown in non-renewed nutrient solution was significantly reduced compared to plants grown in renewed nutrient solution. When plants were grown in non-renewed solution and sprayed Ala, Cys, Glu, Hyp, Lys, Thr, Trp, His and Phe, the growth improved whereas, yield were improved by spraying of Ala, Asn, Asp, Cys, Glu, Gln, Hyp, Lys, Orn, Thr, Trp, His, Phe and Val. Based on growth and yield performance, Ala, Glu, Hyp, Thr, His and Phe were selected for further investigation along with GABA following Wagner's pot hydroponic system and also in vitro condition. Glu and Hyp sprayed plants produced about 50% greater fruit yield compared to water spray as control in Wagner's pot hydroponic system. Effects of amino acids on strawberry plant growth improvement during autotoxicity were confirmed following in vitro culture, where environmental factors and microbial degradation of amino acids were excluded. Results showed that leaf dry weight of Hyp treated plants and root dry weight of Ala, Glu, Hyp, Thr and GABA treated plants were improved against control. Therefore, foliar spray of Glu and Hyp on strawberry plants can recover the growth and yield during autotoxicity in closed hydroponic system.