Effects Of Initiator Combination On Germination Quality Of Tomato Seeds

Tomato(Solanum lycopersicum L.)is one of the most widely cultivated vegetables in the world.And seed is one of the most important means of production,its quality will affect the production and quality of the product.The seed vigor will reach the peak when seeds were physiological maturity.While seed vigor will gradual decline when seeds were stored under improper condition or stored too long,which will lead to quality decline or the differences of seed vigor.Close attentions had always been paid to the improvement of seed vigor in physiological research and crop cultivation area.But there are few reports about how combined priming improve tomato seed vigor,or how combined priming improve seed quality with different vigor levels.In this experiment,tomato stock seeds 'Guozhen No.1' were used as plant material to study the effects of combined priming on germination quality of tomato seeds.Firstly,seeds with high,medium and low vigor were obtained by accelerate aging,then different concentrations of salicylic acid(SA)?thiourea(TU)?naphthylacetic acid(NAA)?gibberellin(GA)?mannitol(MNT)?Polyethylene glycol(PEG)?sodium chloride(NaCl)?chitosan(CTS)?calcium chloride(CaC12)?calcium nitrate[Ca(NO3)2]were adopted to treat seeds with different vigors,and 3 single initiators with a proper concentration were screened out.Using principal component cluster analysis method,the effects of different combinations with the 3 initiators were evaluated,and we screened out the optimal initiator combination.Finally,the physiological and biochemical mechanism of seeds quality improvement induced by priming were studied,which can provide important theoretical basis and practical reference for seeds quality improvement.1.Obtaining tomato seeds with 3 different vigors:Tomato stock seeds 'Guozhen No.1'were treated in the condition of artificial aging(40??RH100%),and the seed germination rate and vigor index decreased with the increase of aging time.We obtained seeds with high,medium and low vigors when seeds were aging for 0?2?3 days respectively.2.The screening of single initiator and its concentration:10 single initiators were selected to treat the seeds.The results indicate that,in this test,except for 0.4 g·L-1 SA and 0.08 g·L-1 NAA,which could inhibit the seed vigor,the other initiator and concentration,specifically SA?TU?NAA?GA?MNT?PEG?NaCl?CTS?CaCl2?Ca(NO3)2 could increase the vigor index of tomato seeds with different vigor.The optimal initiators were 0.2 g·L-1 GA?2 g·L-1 CTS?10 g·L-1NaCl.3.The screening of combined initiators:Based on the 3 kinds of initiators with the best priming effect,a combined priming was used to evaluate the priming effect on tomato seeds.And main component-cluster analysis method were used to evaluate the priming effect of combined initiators on tomato seeds.For high vigor seeds,different initiator combinations lead to rankings:NaCl+GA+CTS>NaCl+CTS>GA+CTS>NaCl+GA>NaCl>GA>CTS>CK;for middle vigor seeds:NaCl+GA+CTS>NaCl+CTS>NaCl+GA>GA+CTS>CTS>NaCl>GA>CK;for low vigor seeds:NaCl+GA+CTS>NaCl+GA>GA+CTS>NaCl+CTS>CTS>GA>NaCl>CK.4.The clustering analysis for combined initiators:The principal component analysis score of each treatment was used as a new index to evaluate the effect and cluster analysis was conducted to get the classification grades of tomato seeds under different priming treatments,the rank for three kinds of vigor seeds:first class:NaCl+GA+CTS;second class:NaCl+GA?NaGl+CTS?GA+CTS;third class:NaCl?GA?CTS;fourth class:CK.5.Physiological and biochemical mechanisms analysis for initiator combination improving tomato seeds vigor:10 g·L-1 NaCl+0.2 g·L-1 GA+2 g·L-1 CTS,the best combined initiator was used to treat the seeds with 3 different vigors.The results showed that the initiator increased seed soluble sugar and soluble protein content,which could provide the energy and material guarantee for seed germination;the initiator also enhanced the activity of antioxidant enzymes and decreased the content of MDA,which could increase the antioxidant system of seed;priming simultaneously increased the endogenous GA and IAA content,reduced the inhibition of germination of endogenous ABA content,which fasted the seeds germination,and ultimately improve the quality of seeds with different vigors.