A large number of plants of similar phenotype are selected and their seeds are mixed together to constitute the new variety. The plants are selected on the basis of their appearance or phenotype. Therefore selection is done for easily observable characters like plant height, ear type, grain colour, grains size, disease resistance, tillering ability, lodging resistance, shattering resistance etc.,
समान फेनोटाइप के पौधों की एक बड़ी संख्या का चयन किया जाता है और नई किस्म का गठन करने के लिए उनके बीजों को एक साथ मिलाया जाता है। पौधों को उनकी उपस्थिति या फेनोटाइप के आधार पर चुना जाता है। इसलिए चयन आसानी से अवलोकन योग्य पात्रों जैसे पौधे की ऊंचाई, कान के प्रकार, अनाज का रंग, अनाज का आकार, रोग प्रतिरोधक क्षमता, सरकने की क्षमता, प्रतिरोध दर्ज करने, बिखरने के प्रतिरोध आदि के लिए किया जाता है।
Sometimes yield of the plant may be used a criterion of selection. If the population has variation for grain characteristics like seed colour and seed size, selection may be done for them before the seeds of selected plants are mixed together.
Generally, the plants selected in mass selection are not subjected to progeny test. Incase of self-pollinated crop, mass selection has two major applications
- Improvement of desi or local varieties.
- Purification of the existing pureline varieties.
Mass selection has only a limited application for the improvement of self-pollinated crops. It is generally not used for the handling of segregating populations derived from hybridization.
In cross-pollinated crops, mass selection leads to avoid inbreeding depression, loss in vigour and yield. Further because of the heterozygous nature of the population, several cycles of mass selection may effectively be practiced.
- The varieties developed through mass selection are likely to be more widely adapted than purelines. It is generally accepted that a mixture of closely related purelines is more stable in performance over different environments than a single pureline.
- Extensive and prolonged yield trials are not necessary. This reduces the time and cost needed for developing a new variety.
- Mass selection retains considerable genetic variability.
- It is a less demanding method. The breeder can devote more time to other breeding programmes.
- The varieties developed through mass selection show the variation and are not as uniform as pureline varieties. Therefore such varieties are generally less liked than pure line varieties.
- The improvement through mass selection is generally less than that through pureline selection. It is because at least some of the plant progenies which make up the new variety would be poorer than the best pureline that may be selected from among them.