Vol. 12, Issue 3 (2023)

Author(s):
V Jegadeeswari, KR Vijayalatha, K Arunkumar and J Suresh

Abstract:
Abiotic stress due to drought is a worldwide issue. During drought condition, plants tend to reduce their activity and try to end their life cycle. Cocoa is considered as a third most important plantation beverage crop after tea and coffee. Whereas the cocoa production was considerably affected by drought and root is an effective parts under water stress condition. Hence, the study was carried out to select best cocoa genotypes based on root morphology and nutrient uptake pattern at Department of Spices and Plantation Crops, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore during 2018-2019.A survey was conducted in two different regions of Coimbatore districts namely Vedapatti and Thondamuthur and 35 plus trees were identified. These 35 plus trees were subjected to different irrigation regimes (100 per cent and 50 per cent field capacity). The performance of seedlings of plus trees under different irrigation regimes were evaluated based on root morphology and nutrient uptake characters like root length, root girth, fresh root weight, root volume, root girth, dry root weight, number of roots, root nitrogen, root phosphorus and root potassium. With respect to root morphology parameters, highest root length (38.6 cm) was registered in Tc (Vedapatti) 29 and maximum fresh root weight (16.38 g), root girth (2.98 g), dry root weight (6.76 g) and number of roots (62) were recorded in Tc (Vedapatti) 2 under water stress condition (50% field capacity) than control (100% field capacity). With regard to nutrient uptake pattern, the highest root nitrogen (1.84%) and root potassium (1.50%) were recorded in Tc (Vedapatti) 2 and root phosphorus (0.63%) in Tc (Vedapatti) 29 under drought condition than control. Based on statistical analysis, significant variation was observed among the 35 plus trees seedlings under 50 per cent field capacity. In respect of root morphology and nutrient uptake parameters, genotypes with highest root length, number of roots, root volume, root weight; likewise maximum root nitrogen, phosphorus and potassium can effectively tolerate drought condition. From this study it is concluded that Tc (Vedapatti) 2 and Tc (Vedapatti) 29 exhibited the exact root morphology and nutrient uptake mechanism required to withstand water stress and can be used for further breeding programmes and as parents for developing hybrids with positive characters.