Phenotyping for Groundnut (Arachis hypogaea L.) Improvement

Groundnut (Arachis hypogaea L.) is grown world over for oil and food uses. It is a self-pollinated crop with low genetic diversity. The origin of the crop from single hybridization event followed by chromosome doubling as well as crossing barriers of cultivated species with wild species due to ploidy differences rendered the crop with narrow genetic variability. Developing new varieties with increased yield potential and resistance to biotic and abiotic stresses that meet the needs of the growers, processors and consumers is the primary objective of groundnut breeding. In this chapter, we discuss about phenotyping tools used in groundnut improvement programs for various targeted traits. Both field and laboratory tools are described to screen for resistance to diseases caused by fungi, bacteria, virus and nematodes. Phenotyping based on Cumulative Thermal Time (CTT) is used to select for early maturity. Phenotyping for complex traits can be challenging. Either empirical approach that involves measuring the yield under imposed drought stress or salinity conditions or trait based approach using surrogates or a combination of both are used for phenotyping abiotic stresses. Phenotyping for Aspergillus contamination needs improvement to derive reliable and reproducible results. Estimation of quality and nutritional parameters generally involves use of destructive and laborious chemical or physical procedures. Near infrared reflectance spectroscopy (NIRS), a robust and non-destructive method is gaining popularity for estimation of oil, protein, carbohydrate and fatty acid contents. Methods for estimating oil, protein, sugar and micronutrient concentrations and fatty acid composition of seeds and haulm quality traits are describe