We feel that the traditional approaches of plant breeding are of empirical types since they have not utilized the knowledge of physiological and morphological characters related to economic yield of crops. One has, therefore, to look forward for some new components which have been ignored so far to achieve higher yield. For example, it has been found in maize that the initial number of ears per plant, number of ovules per ear and actual ear length are usually more than the effective number of ears per plant, number of grains per ear and effective ear length, respectively. If these initial characters are somehow realized in the hybrids, through high conversion capacity (of number of ovules into number of grains, for example) without reducing the 100 grain weight, that would help in increasing the grain yield.
With these objectives in mind we gathered information on thirteen such characters in four inbreds, namely CM 202, CM 111, CM 400 and CM 300 and their two F1 single crosses (CM 202 x CM 111 and CM 400 x CM 300). It was found that the inbreds, as well as the hybrids, possessed significantly fewer effective ears per plant, grains per ear and shorter effective ear length in comparison to the corresponding number of total ears initiated per plant, number of ovules formed per ear and actual ear length, respectively (Table 1). A perusal of the data also indicates that CM 400 possessed a fairly high number of grains per ear because of its high harvest index, fairly high percentage of grain conversion and high proportion of effective ear length. Similarly the cross CM 202 x CM 111, which possesses the highest number of ovules per ear and high percentage grain conversion, could also possess the highest number of grains per ear. It therefore appears that the hybrid still possesses some scope for improvement in other characters like harvest index and percent effective ears per plant. CM 400 x CM 300 also gives a similar picture. Hence, we feel that parents having high performance in any of these components should be selected for the breeding programs to evolve genotypes with fairly high mean values in all these components (along with high 100 grain weight) to increase the present day grain yield of maize.
Table 1. Part 1. Part 2.
B. C. Saha and B. K. Mukherjee
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