Cucumber seedling dependence on cotyledonary leaves for early growth

Abstract

-The objective of this work was to evaluate the dependence of cucumber (Cucumis sativus L.) seedlings on cotyledonary leaves for early growth and establishment. Sets of two uniform emerging seedlings were used to quantify the initial growth and dry matter accumulation, as well as the intensity and stage of cotyledon damage in seedling establishment and to determine cotyledon protein, amino acid and carbohydrate contributions to the growing seedling. Cucumber seedling establishment was found to be highly dependent on cotyledonary leaves. Root system establishment was highly dependent on the health of the aerial part. One cotyledon was enough to maintain aerial growth of seedlings after unfolding the first true leaf. Cucumber seedlings depended on both cotyledons to keep root system growth at least until leaf area was equivalent to cotyledon area. Covering one or both cotyledons of seedlings with one unfolded leaf increased carbohydrate content of uncovered cotyledon and leaves compared with control seedlings. Cucumber seedlings are highly dependent on cotyledonary leaves and aerial parts are less dependent than root system. Cotyledon damage at early stages of plant establishment would adversely impact crop yield by reducing plant density, an important yield component, or slowing down seedling growth and establishment.Index terms: Cucumis sativus, cotyledon excision, cotyledon coverage, dry matter, leaf area. Dependência das folhas cotiledonares para o crescimento inicial de pepinoResumo -O objetivo deste trabalho foi estudar o desempenho das folhas cotiledonares no crescimento inicial e estabelecimento de plântulas de pepino (Cucumis sativus L.). Grupos de duas plântulas uniformemente emergidas foram utilizados para quantificar o crescimento inicial e acúmulo de matéria seca, o efeito da intensidade e época de remoção dos cotilédones sobre o estabelecimento da plântula, e a contribuição de proteínas, aminoácidos e carboidratos dos cotilédones para o crescimento inicial. O estabelecimento das plântulas de pepino foi altamente dependente das folhas cotiledonares. As folhas cotiledonares foram fundamentais para o estabelecimento do sistema radicular. A presença de um cotilédone após a emissão da primeira folha verdadeira foi suficiente para manter o crescimento da parte aérea da plântula. Plântulas de pepino foram dependentes de ambas as folhas cotiledonares para sustentar o crescimento do sistema radicular, pelo menos até a equivalência entre área foliar e cotiledonar. A cobertura de uma ou ambas folhas cotiledonares antes da emissão da primeira folha verdadeira aumentou o conteúdo de carboidratos no cotilédone descoberto e nas folhas, comparado com a testemunha. O crescimento inicial de plântulas de pepino é altamente dependente das folhas cotiledonares, sendo a parte aérea menos dependente do que o sistema radicular. Danos nos cotilédones durante o crescimento inicial podem afetar o rendimento pela redução da densidade de plantas, um importante componente do rendimento, ou da taxa de crescimento e estabe...

Fatty Alcohol Application to Control Meristematic Regrowth in Bottle Gourd and Interspecific Hybrid Squash Rootstocks Used for Grafting Watermelon

“…Because at least one cotyledon is required for grafting success (Bisognin et al, 2005;Memmott, 2010), it was necessary to determine the effect of the fatty alcohol application on cotyledon damage as well as on regrowth control to ensure rootstock quality for grafting. For cotyledon damage, a rating of 0 was assigned to seedlings with no visible damage ( Fig.…”

“…The two most common commercially used grafting methods (over 90%) are the hole-insertion and the one-cotyledon method (Hassell et al, 2008). These methods require at least one cotyledon to remain intact to ensure graft success (Bisognin et al, 2005;Hassell et al, 2008), and both require manual meristem removal with a blade during grafting. This method often removes the meristem only partially, and meristem regeneration occurs.…”

“…However, acceptable removal of the meristem without damaging the rootstock cotyledons has been a challenge. Preserving the quality of the cotyledons is essential, because cucurbit seedlings rely heavily on at least one cotyledon to supply energy for growth and establishment (Bisognin et al, 2005). A chemical treatment would be acceptable for use only if it could destroy the meristem without damaging the cotyledons, which would provide the energy required for rootstock health and graft healing.…”

Increasing Survival of Splice-grafted Watermelon Seedlings Using a Sucrose Application

“…The two most commonly used grafting methods for commercial production of grafted watermelon transplants are the hole-insertion and the onecotyledon methods (Hassell et al, 2008). Both of these methods require at least one cotyledon to remain on the rootstock to ensure graft success (Bisognin et al, 2005;Hassell et al, 2008). However, to prevent rootstock growth with these methods, the meristem tissue at the base of the rootstock cotyledon must be completely removed.…”

Effect of a Short-Term Daily Temperature Drop on the Cold Tolerance of Leaves of Different Age

“…Еще одной причиной меньшей устойчивости молодых листьев может быть более высокая у них интенсивность метаболизма, поскольку известно, что клетки с повышенным метаболизмом характеризуются пониженной устойчивостью к действию стресса [Irwin, Prica, 1983]. В то же время зрелые листья отличаются от растущих повышенным содержанием сахаров, аминокислот и ряда других веществ, участвующих в устойчивости клеток к действию неблагоприятных факторов [Bisognin et al, 2005;Cabello et al, 2006]. Приведенные выше факты могут служить причиной различий в реакции листьев разного возраста, в том числе формировании повышенной холодоустойчивости под влиянием ДРОП-воздействий.…”