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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #330797

Research Project: Genetic Enhancement of Lettuce, Spinach, Melon, and Related Species

Location: Crop Improvement and Protection Research

Title: Drench application of fish-derived protein hydrolysates affects lettuce growth, chlorophyll content, and gas exchange

Author
item Xu, Chenping
item Mou, Beiquan

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2017
Publication Date: 9/5/2017
Citation: Xu, C., Mou, B. 2017. Drench application of fish-derived protein hydrolysates affects lettuce growth, chlorophyll content, and gas exchange. HortTechnology. 27:539-543.

Interpretive Summary: The use of plant stimulants to enhance crop production has gained considerable momentum because of its contribution to agricultural and ecological sustainability. Protein hydrolysates (PHs) are an important group of plant stimulants that have received increasing attention in recent years due to their positive effects on crop performance. Short-term (30-days after transplanting) effects of fish-derived PHs, applied as a drench (3 ml/liter at 0, 14, and 24 d after transplanting), on soil properties and lettuce growth and physiology were evaluated in a growth chamber study. After harvesting, soil treated with PHs had higher C/N ratio and content of K and Fe, lower value of pH, electrical conductivity, water holding capacity and cation exchange capacity, and lower content of NO3-N, P, Mg, SO4, Cu, Mn, B and Na, than soil without PHs. Application of PHs increased lettuce leaf number, stem diameter, shoot fresh and dry mass, and root dry mass. It also increased leaf relative water content and succulence but had no effect on specific leaf area. Protein hydrolysates increased leaf chlorophyll content, photosynthetic rate and transpiration although they did not alter chlorophyll photochemistry. Our study indicated that as plant stimulants PHs are effective tools for sustainable production of lettuce.

Technical Abstract: The use of biostimulants to enhance crop production has gained considerable momentum because of its contribution to agroecological sustainability. Protein hydrolysates (PHs) are an important group of plant biostimulants that have received increasing attention in recent years due to their positive effects on crop performance. Short-term (30-days after transplanting) effects of fish-derived PHs, applied as a drench (3 ml L-1 at 0, 14, and 24 d after transplanting), on soil properties and lettuce (Lactuca sativa L) growth and physiology were evaluated in a growth chamber study. After harvesting, soil treated with PHs had higher C/N ratio and content of K and Fe, lower value of pH, electrical conductivity, water holding capacity and cation exchange capacity, and lower content of NO3-N, P, Mg, SO4, Cu, Mn, B and Na, than soil of the control. Application of PHs increased lettuce leaf number, stem diameter, shoot fresh and dry mass, and root dry mass. It also increased leaf relative water content and succulence but had no effect on specific leaf area. Protein hydrolysates increased leaf chlorophyll content, photosynthetic rate, stomatal conductance and transpiration although they did not alter chlorophyll fluorescence. Our study indicated that as plant biostimulants PHs are effective tools for sustainable production of lettuce.