Stomatal Conductance and Photosynthesis

TLDR

The ICT has been developing superior cocoa genotypes for several years. This study aims to identify cocoa genotypes that tolerate water stress while resisting pests and diseases and maintaining high production and industrial quality. Twenty cocoa genotypes were grown for six months in sandy‑loam soil under controlled irrigation, using a split‑plot design with 40 treatments and three replications, while daily temperature, humidity, and stomatal conductance were recorded. Moderate water‑stress tolerance was observed in UNG‑77, UNG‑53, ICT‑1281, and ICT‑1112, whereas PAS‑93, CEPEC‑2002, and others were non‑tolerant; under optimal conditions, IC S‑1 excelled in height, leaf number, and stomatal conductance.

Abstract

This research is part of an effort that the ICT (Institute of Tropical Cultivation) has been doing for several years tending to develop superior genotypes of cocoa (Theobroma cacao L.). That is why this study aims to find tolerant or moderately tolerant cocoa genotypes and accessions to water stress with resistance to pests and diseases and high production and industrial quality. Twenty genotypes of cocoa seedlings were investigated, during the period of 6 months, in a soil with sandy-loam texture under nursery conditions, of controlled irrigation. A split plot design was used, with 40 treatments and 3 repetitions. In addition, daily data of the micro climatic characteristics (T °, HR) were taken, in which different indicators of variable were evaluated such as the stomatal conductance (CE) that is greatly influenced by the T ° and HR. The results obtained indicate that the genotypes that showed moderate tolerance to water stress were UNG - 77, UNG - 53, ICT - 1281 and ICT - 1112; the non-tolerant ones were PAS - 93, CEPEC - 2002, ICT - 2142, ICT - 1092, CP - 2005 - C10, TSH - 1188, CCN - 51, IMC - 67, PH - 17, AYP - 15,ICS - 6, BN - 34, ICT - 1506, PAS - 91, PH - 990 and ICT - 1. Under optimal conditions, the most outstanding genotype was ICS-1, both in plant height, number of leaves, and stomatal conductance, this being proof that this genotype develops excellently and stands out if it has the right conditions and water availability.