Photosynthesis-Related Responses of Colombian Elite Hevea brasiliensis Genotypes under Different Environmental Variations: Implications for New Germplasm Selection in the Amazon.

Armando Sterling,Juan Carlos Suárez,Natalia Rodríguez-Castillo,Edwin Andrés Clavijo-Arias,Lised Guaca-Cruz

doi:10.3390/plants10112320

Abstract

The objective of this study was to evaluate photosynthetic performance based on gas exchange traits, chlorophyll a fluorescence, and leaf water potential (ΨL) in nine Hevea brasiliensis genotypes from the ECC-1 (Élite Caquetá Colombia) selection and the cultivar IAN 873 (control) in response to different climatic (semi-humid warm and humid warm climates), seasonal (dry and rainy periods), and hourly (3:00 to 18:00) variations that can generate stress in the early growth stage (two-year-old plants) in two large-scale clonal trials in the Colombian Amazon. The photosynthetic performance in 60% of the Colombian genotypes was slightly affected under the conditions with less water availability (dry period, semi-humid warm site, and between 9:00 and 15:00 h), as compared with IAN 873, whose affectation was moderate in terms of photosynthesis rates, but its water conservation strategy was strongly affected. The ECC 90, ECC 83, and ECC 73 genotypes had the best photosynthetic performance under conditions of greater water limitation, and ECC 35, and ECC 64 had a higher water status based on the leaf water potential, with intermediate photosynthetic performance. This germplasm has a high potential for selection in rubber tree breeding programs in future scenarios of climate change in the Colombian Amazon.

Highlights

The present study showed how climatic, seasonal, and diurnal variations can affect the photosynthetic performance of H. brasiliensis during the early growth stage, and how genotypic variation can be used for the early selection of genotypes with desirable photosynthetic characteristics
The photosynthetic performance in 60% of the Colombian elite H. brasiliensis genotypes was little affected under the conditions of less water availability, as compared with cultivar IAN 873, which was moderately affected in terms of photosynthesis rates but strongly affected in relation to its water conservation strategy
Greater increases in water potential in the pre-dawn (3:00 h) or in the efficiency to capture, use and dissipation of light energy in photosystem II during the dry period for increasing the photosynthetic rate, and the leaf water potential between 9:00 and 12:00 h were the main strategies used by the Colombian genotypes to minimize the impacts of lower water availability in the soil during that period

Summary

Introduction

In regions with a high rubber tradition such as Caquetá (northwestern Amazon), cultivation has been promoted that has a reduced genetic base (four cultivars) that is highly susceptible to phytosanitary problems and has low physiological and productive performance [4,5,6]. This genetic base is represented in some 6700 ha, whose yield has decreased from 1.3 to 0.9 tons per ha per year in the last 15 years, affecting more than 1200 families that depend on this crop in the region [7]. The need to renew current plantations with new high-performance genetic materials is a priority in the Amazon region

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