The growth responses of seedlings and plantlets to stress conditions in three anthocyaninless tomato (Lycopersicon esculentum Mill.) mutants

Genes ah, aw and bls speed up the germination in tomato. The present study was undertaken to test whether these genes might also influence the subsequent growth of seedlings and young plantlets under optimal and stress conditions. Two groups of experiments were carried out: (A) stress during the stages "germination-cotyledons emergence"and "cotyledons emergence-third expanded leaf"and (B) stress during the earlier stages "seed imbibition-radicle protrusion"and "radicle protrusion-cotyledons emergence". The results have shown that the earlier cotyledons emergence and more rapid plantlet development of the anthocyaninless mutants were due to their earlier germination. They depended on the genotype and on the treatment, and could not be attributed to their greater ability to recover after stress, or to more intensive growth under optimal and stress conditions.Effet des conditions défavorables sur la croissance des radicules et des plantules chez trois mutants de tomate (Lycopersicon esculentum Mill.) caractérisés par l'absence d'anthocyane. Le but de l'étude était de tester l'hypothèse selon laquelle les trois gènes mutants ah, aw et bls qui accéléraient la germination chez la tomate dans des conditions optimales et défavorables pourraient exercer un effet similaire sur le développement ultérieur des radicules et des plantules. Deux groupes d'expériences ont été effectués : (a) application du stress durant les stades "germination- émergence des cotylédons "et "émergence des cotylédons-apparition de la troisième feuille "et (b) application du stress durant les stades précédents, i.e., "imbibition des graines-germination "et "germination-émergence des cotylédons ". Les résultats obtenus ont montré que l'accélération de l'émergence des cotylédons et du développement des plantules observée chez certains mutants sans anthocyane était liée à leur germination plus rapide et dépendait du génotype et du traitement. Cette accélération n'a pas pu être attribuée à une meilleure aptitude à recouvrer une croissance normale après un stress ou bien à un développement plus rapide en conditions optimales et défavorables

THE EFFECTIVENESS OF GRAFTING TO IMPROVE SALTTOLERANCE OF SENSITIVE MELON WHEN THE TOLERANT MELON ISUSED AS ROOTSTOCK

Melon cultivars that are sensitive and tolerant to salinity were reciprocally grafted andplants were grown under salinity and control conditions in the glasshouse. Growing culturewas vermiculite and plants were irrigated by the complete nutrient solution. Thirty days oldmelon plants, grafted and ungrafted were subjected to salinity stress during 25 days with100mM NaCI. Some physiological parameters were investigated. Grafting on the tolerantmelon increased the responses of the sensitive melon to salinity in comparison to theungrafted one. The shoot fresh weight and leaf area were increased by 27%, leaf waterpotential was increased by 65%, leaf membrane injury index was decreased by 13 andstomatal conductance was increased by 18%. Other parameters like chlorophyll content, leaftemperature, mineral content (Na, K, Ca, and Cl) of the leaf and root, antioxidative enzymeactivities were also investigated. All results were discussed in the meeting in Portugal.</p