Effect of nutrient starvation on some aspects of nitrogen metabolism in substrate-grown strawberry plantings cv. Nyoho

Abstract

Three-week nitrogen (N) supply restriction is a way to stimulate early and uniform flower induction in forced June-bearing nursery strawberry production in Japan. In the first weeks after planting into excessively-fertigated substrates, N-starved plantings undergo drastic changes in their N utilization and N metabolism, often facing symptoms of interveinal chlorosis in their young expanding leaves. Interveinal chlorosis is reflected in delayed plant development, and consequently in yield reduction. Characterizing variations in main parameters of N metabolism in plant tissues in N-fed and N-starved strawberry plantings cv. Nyoho, this report portrays the pattern of changes in N metabolism during the nursery period. Results show that foliar NH4-N and petiole NO3-N concentrations and N-assimilating enzymes activities in plant tissue were significantly reduced due to the N-starvation, making young plants unlikely to be adaptive to N rich nutrition after planting, and that subsequent NH4-N accumulation in plant tissues can lead to sever interveinal chlorosis.

Dinje, lubenice i jagode u Japanu pripadaju povrtarskim vrstama. Poslednja dekada avgusta je period kada prestaje svako đubrenje, a pogotovo đubrenje azotnim đubrivima sadnica rasada jednorodnih (junskih) jagoda namenjenih gajenju u plastenicima u uslovima forsirane proizvodnje. Ovako 'izgladnele' biljke se krajem septembra presađuju u supstratske podloge (plastične kese punjene tresetom) koje se zatim intenzivno đubre, čime se podstiče ranije i uniformnije zametanje cvetova. Rezultati ove studije su pokazali da tokom gladovanja u fazi rasada koncentracije amonijačnog i nitratnog jona i aktivnosti enzima koji učestvuju u asimilaciji azota u biljnom tkivu značajno opadaju. Nakon presađivanja u supstratske podloge, ove 'izgladnele' mlade biljke su teško adaptibilne na uslove intenzivne prihrane azotom, te u svom tkivu akumuliraju amonijačne jone što neretko rezultira intervenalnom hlorozom mladog lisnog tkiva. Hlorotične biljke zaostaju u razvoju i daju smanjene prinose.