Ground peach pits: alternative substrate component for seedling production

The exploitation of agro-industrial wastes is a strategy to add value to seedling production and reduce environmental problems.The production chain for processed peaches generates,approximately,21,000 tons of fruit worldwide,and the pits are used mainly to generate energy.The objective of the study was to investigate the use of different proportions of ground peach pits(GPP)as a substrate component for seedling growth of Eucalyptus dunnii in the nursery and field.Different proportions of GPP mixed with either commercial substrate(CS)or with brown peat(BP)were tested.The physical and chemical properties of the substrates,the morphological and physiological attributes of the seedlings and their correlation with substrate properties were evaluated.The GPP increased the density,aeration space and pH and reduced total porosity,liquid retention and electric conductivity of the substrate.The use of this component resulted in hormesis,a biphasic dose–response model in which low levels of exposure to this component stimulated biological performance of plants and high levels of exposure inhibited performance.For improved seedling growth in the nursery and adequate post-planting development of E.dunnii,GPP with CS is recommended at 20%of the total substrate and with BP between 15 and 30%.

Morphophysiological responses of forest seedling species subjected to different water regimes

Water availability is a limiting factor for the establishment and development of forest species.To understand the appropriate conditions for the initial post-transplanting phase,it is necessary to understand the specific morphophysiological characteristics of the species,such as the leaf water potential and the efficiency of photosystemⅡ.We aimed to identify the influence of different water regimes on the morphophysiological aspects of young plants of two forest species(Cedrela.fissilis Vellozo and Eucalyptus saligna Sm.).Two greenhouse experiments were conducted for 28 days;one for each species.The design was completely randomized,and the treatments consisted of six different water regimes.Leaf water potential(Ψw)and chlorophyll a fluorescence were evaluated every 7 days.At the end of the experiment,morphological attributes(height,collection diameter,root volume,and dry matter)were measured and histological blades were made.The water demand of E.saligna was higher than that of C.fissilis and required greater replacement within a shorter period.The rehydration fromΨw=-2 Mpa allowed for a fast recovery of the young C.fissilis plants(Ψw=-1.5,Fv/Fm=0.796),which indicated good physiological plasticity of this species when submitted to water stress at a level that is not severe.The total dry matter allocation was different among species.Seedlings of E.saligna presented the best responses when submitted to a continuous water supply regime,while C.fissilis seedlings presented the best response under intermittent irrigation conditions.

Morphological,physiological and biochemical traits of Cordia trichotoma under phosphorous application and a water-retaining polymer

The application of phosphorus(P)and a waterretaining polymer to the soil can increase the availability of P for Cordia trichotoma,having a positive effect on the plants.The objective of this study was to evaluate the morphological,physiological and biochemical characteristics of C.trichotoma plants were cultivated in a red argisol and treated with 120,240 and 360 kg P2O5 ha^(−1)and no phosphorous addition as a control,in the presence(5 g L^(−1)per seedling)and absence of a water-retaining polymer.Twentyfour months after planting,survival,height,stem diameter,shoot and root dry matter,leaf area,photosynthetic pigment concentration,chlorophyll a fluorescence,acid phosphatase enzyme activity(APase)and P in tissues and soil were determined.The polymer had no effect on survival and the other parameters.The addition of P increased growth,dry matter production,photosynthetic pigment concentrations,the use of light energy and maximum quantum yield of photosystem II.Plants cultivated in soil with 240 kg P2O5 ha^(−1)application had 4.7 and 5.4 times more shoot and root dry matter,respectively,than control plants.This dosage also showed 52.1%greater photochemical energy use than the control plants.Plants cultivated without the addition of P showed higher activity of the APase enzyme.