Influencia del portainjerto en los cambios hormonales durante el proceso de cuajado en plantas de pimiento sometidas a estrés supra-térmico

Abstract

[ES] En este trabajo se pretende evaluar los cambios hormonales que pueden producirse durante el proceso de cuajado, en función de las condiciones ambientales de estrés supra-térmico y del portainjerto utilizado en el cultivo de pimiento. Para ello, se cuantifican y se analizan los contenidos de diferentes hormonas relacionadas con el desarrollo del fruto y sobre las condiciones de estrés, de ovarios de frutos de pimiento en 5 momentos del proceso de cuajado, antes y después de la antesis, en plantas de pimiento injertadas sobre un portainjerto tolerante y otro sensible a las altas temperaturas, sometidas a condiciones control y condiciones de estrés térmico, en cultivo en invernadero.

[EN] Heat stress is a great limitation in today´s horticultural production. High temperatures reduce significantly fruit set percentage and impact aspects like pollen viability. Grafting usage is a sustainable, appropriate alternative, which contributes to increase fruit set percentage and reduce heat stress negative effects, as long as heat stress tolerant rootstocks are used. Since the growth regulators have a great importance in fruit set and high temperatures can impact their concentration in the plant, in the present thesis ovaries´ contents of different growth regulators (IAA, gibberellins, ACC, cytokines, ABA, jasmonic acid and salicylic acid) have been analysed in early fruit set (from -1 to 4 days after anthesis). This has been done to study the different concentrations of growth regulators that plants show when subjected to heat stress or control conditions and to evaluate grafting and rootstock role in those differences. Grafting role has been evaluated by comparing the results obtained from the ungrafted and self-grafted plants, and rootstock role has been evaluated by using one sensitive rootstock and a tolerant one. The results obtained show that in most of the growth regulators evaluated there is an effect produced by heat stress on the concentration of those regulators in the ovary, whereas the influence of grafting does not affect hormonal content in a significant way during the fruit set, although we can observe differences in the global concentration of cytokines and salicylic acid, and occasional differences depending on the growth regulator and the stage considered. Using a sensitive or tolerant rootstock also affects the behaviour and concentration of the different plant growth regulators, having a marked effect on GA3 concentration in the last stage analysed, which is much higher in the tolerant rootstock; and also, in ACC content during anthesis, being the tolerant rootstock the only one in which there is no difference between stress and control ACC levels. All this said, treatment factor (stress) is the most influential when explaining changes in growth regulators concentration during the time studied