Agronomic Traits Assessment and Growth and Yield Responses of Selected Spider Plant (Cleome Gynandra L.) Accessions to Water Stress

Abstract

African leafy vegetables (ALVs) are vegetables that are locally consumed and whose edible parts include leaves, young shoots and flowers. They have a crucial role in enhancing food security, nutrition, biodiversity, income and sustainable development in Kenya. Spider plant (Cleome gynandra L.) is one of the ALVs with a great potential for improving food security and income among rural and urban resource-poor communities. However, its productivity is low partly due to lack of suitable varieties, poor soil fertility, drought stress and poor agronomic practices. Currently, there is scanty information on its potential for vegetable and seed production and adaptability to water stress. Therefore, the objectives of this study were: (i) to evaluate the agronomic traits of selected spider plant accessions; and (ii) to determine the effect of water stress on growth and yield of selected spider plant accessions. In the first objective, a study was conducted at Kabete in the field and greenhouse and on-farm in Migori County to assess agronomic traits of 40 selected spider plant accessions using a randomized complete block design with three replications. In the second objective, 14 selected Kenyan spider plant accessions were grown under soils at 40%, 60%, 80% and 100% field capacity (FC) conditions in a greenhouse at Kabete between June 2018 and March 2019. In both experiments, data was collected on plant growth, physiological and yield attributes and subjected to analysis of variance using GenStat 15th edition at 5% probability level. Number of days to emergence and emergence level varied from 4 (accessions GBK-045436) to 12.7 (accessions GBK-032302 and GBK-031992) and 23.1% (accession Baringo) to 59% (Commercial variety), respectively. Number of leaves per plant and seed yield per plant varied from 23.2 (accession Mombasa) to 121.7 (accession GBK-028563) and 0.3 g (accession Mombasa) to 16.8 g (accession GBK-045456), respectively. Plant height ranged from 16.0 cm (accession Mombasa) to 107.1 cm (accession GBK-045436), while 100 seed weight varied from 60 mg (accession Mombasa) to 170 mg (accession GBK-031994). Number of leaves per plant were proportional to number of primary branches (R2 = 0.81, P≤0.01) and plant height (R2 = 0.87, P≤0.01). Water stress reduced plant height by 9.9%, 26.2%, and 38.5%, and leaf yield by 25.7%, 55.1%, and 74.2% at 80%, 60% and 40% field capacity, respectively. Pod number per spider plant reduced by 17.0%, 47.9%, 61.5% and seed yield per spider plant by 43.9%, 77.9% and 90.6% at 80%, 60% and 40% FC, respectively. Chlorophyll content reduced by 11.3%, 26.7%, 38.2% at 80%, 60%, 40% FC, respectively. Results indicate that there exist significant genotypic differences among the evaluated spider plant landraces and the commercial variety in adaptation to drought. The responses to drought in most of the physiological, growth and yield parameters were dependent on the accessions. Genotypes that expressed superior agronomic traits for yield such as accessions GBK-032210, GBK-040449, GBK-031991 Kakamega and GBK-045456, point to the existence of exploitable drought tolerance genes in spider plant landraces that can be utilized in breeding programmes for drought adaptability aimed at improving spider plant growth and yield