TITLE:
Effect of Plant Density on the Yield of Hydroponically Grown Heat-Tolerant Tomato under Summer Temperature Conditions
AUTHORS:
Alex Williams Ayarna, Satoru Tsukagoshi, George Oduro Nkansah, Kazuya Maeda
KEYWORDS:
Heat-Tolerant, Heat Stress, Hydroponics, Plant Density, Tomato, Yield
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.12 No.6,
June
11,
2021
ABSTRACT: Producing enough tomato to meet market demand
sustainably has not been feasible in the tropics like Ghana. Attempts to
improve production using greenhouse
facilities have not addressed the challenge because of high-temperature
conditions in the greenhouse, which are difficult to manage. Heat stress,
arising from high temperatures, hinder the performance of tomato in terms of
fruit set and yield. Moreover, the impending climate change is expected to
impose more unfavorable environmental conditions on crop production. An experiment was conducted in (greenhouse at
Chiba University, Japan) summer period, which has similar
high-temperature conditions like Ghana. This work sought to increase the yield
of a heat-tolerant tomato using a
state-of-the-art hydroponic system through high-density planting. The
outcome of this work was intended for adoption and practice in Ghana. A
Heat-tolerant tomato “Nkansah HT” along with Lebombo and Jaguar cultivars, were
grown at high and low plant densities (4.1 and 2.7 plants m-2 respectively). Each
plant was grown in a low substrate volume culture (0.5 L plant-1) in a recirculating nutrient film technique (NFT)
hydroponic system. Parameters measured were plant growth and dry
matter assimilation at 12 weeks after
transplanting, and the generative components. Results showed that a high
plant density increased plant height but reduced chlorophyll content by 9.6%. Under temperature stress conditions, the three
cultivars recorded more than 95% fruit
set, but plant density did not affect the fruit set and the incidence of
blossom end rot (BER). The incidence of BER reduced the marketable yield
of the Jaguar cultivar by 51% but, this physiological disorder was not recorded
in the HT and the Lebombo cultivars. A high-density planting increased the
yield per unit area increased by 38.9%. However, it is uneconomical to
cultivate the Jaguar cultivar under a heat stress condition due to its high
susceptibility to blossom end rot. To improve the yield of tomatoes under
tropical heat stress with a threatening climate change condition, the HT is a
better cultivar suited for high-density planting. This study shows that high-density
cultivation of the HT cultivar in NFT hydroponic system has the potential to
increase Ghana’s current tomato yield by 4.8 times.