An Easy and Simple Method for Estimating Total Shoot Length During Screening and Evaluation of Mulberry(Morus spp.) Genotypes

In mulberry (Morus sp.), grown for its foliage, which is the sole food for the silkworm (Bombyx mori L.), evolving high yielding varieties is a long drawn and laborious process. One of the important selection parameter that has significant positive correlation with leaf yield is Total Shoot Length [TSL] of the mulberry plant. Measuring the length of all the shoots of the test genotypes to get the total shoot length during several stages of screening and evaluation requires enormous skilled manpower and time. The enormity of the task itself most often than not leads to inaccuracies. Due to multi-collinearity among the characters such as number of shoots, length of the longest shoot and total shoot length, the expression of these characters as a single entity could be more accurate and time saving if appropriate statistical relationships are established. In view of this, a regression relationship was derived and a model developed for estimating total shoot length by measuring only the length of longest shoot and number of shoots per plant. The model was tested with four mulberry varieties that are often used as checks in evaluation experiments and significantly high coefficient of determination [R2] ranging from 0.81 to 0.91 were recorded. Further, evaluation of the models with two mulberry genotypes grown under two distinctly different growing environments also showed no significant difference between the estimated and actual total shoot length. These tests confirmed the efficacy of the models across varieties and growing environments, thus paving way for reduction in drudgery, savings in time and resources in mulberry breeding programmes.