Biostimulants offer an innovative approach to potentially improve crop
yield and quality under abiotic stresses. Particularly, plant-derived protein
hydrolysates (PH), a mixture of amino acids and soluble peptides from enzymatic
or chemical hydrolysis of agricultural waste, are gaining global interest due
to their sustainability and positive effects on crops. However, a functional
role of the PH in crop yield and quality remains uncertain and is proposed to
be associated with its phytohormone-like activities or serve as an additional nitrogen
(N) source. Besides, the effects of PH on crop yield and quality are limited in
intensive production systems such as greenhouse facilities. The
purposes of this research are to examine the effects and mechanisms of PH on
crops and to assess the potential of PH application to reduce fertilizer use in
crop production. The specific objectives were to; 1) elucidate the hormone-like
activities of PH in the adventitious rooting formation of cuttings, 2) evaluate
the effects of different PH application methods on greenhouse crop yield and
quality under different N levels when plants are grown with a commercial
growing medium, and 3) examine the effects of PH application methods on yield
and quality of hydroponically grown lettuce under different N levels and forms.
Three conclusions were that 1) <a>the hormonal effects of
PH are attributed to brassinosteroid-mediated processes, and PH has overlapping
functions with auxin during adventitious rooting of cuttings in a plant
species-specific manner</a>, 2) root application of PH (PH-R) effectively
improves nutrient uptake compared to foliar spray of PH (PH-F), subsequently,
increases the lettuce and tomato yield and quality regardless of N levels while
PH-R did not change the chemical properties of growing media, and 3) PH-R
effectively increases root growth, and subsequently, improving shoot yield and
quality with significant PH × N levels and PH × NO<sub>3</sub>:NH<sub>4 </sub>ratios
interactions. Also, PH-R counteracted the negative effects of low NO<sub>3</sub>:NH<sub>4 </sub>ratios on lettuce yield. The
outcomes provide the optimization of PH and N fertilization in modern
sustainable greenhouse production and the development of a new strategy for
producing high-quality greenhouse crops with improved nutrient use efficiency.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/15081627 |
| Date | 30 July 2021 |
| Creators | Seunghyun Choi (10347350) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/THE_EFFECTS_OF_PLANT-DERIVED_PROTEIN_HYDROLYSATES_ON_THE_GROWTH_QUALITY_AND_PHYSIOLOGY_OF_GREENHOUSE_CROPS/15081627 |
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