Three‐Way Crosses vs. Single Crosses in Tobacco: First Agronomic Assessment

Abstract

In view of the increasing costs and reduced profit margins of tobacco (Nicotiana tabacum L.) production, three‐way‐cross hybrids (TWCHs) of flue‐cured tobacco were developed and examined for their potential to improve the agronomic performance and economic efficiency of the crop. Three TWCHs, each with a pair of related single‐cross hybrids (SCHs), were compared in a replicated field trial performed at two farm locations for two years for the degree of within‐population morphological variation, cured leaf yield, crop quality index, and gross revenue from unit crop area. Some significant differences in quartile coefficient of dispersion (QCD) were recorded for plant height (TWCH‐B vs. unrelated SCHs, among SCHs) and for leaf area (among TWCHs and among SCHs). No significant differences in QCD were detected between TWCHs and any of their related SCHs. Two of the TWCHs showed no significant differences in leaf yield when compared with their single‐cross counterparts. In the third TWCH (i.e., TWCH‐A), there was an overall significant increase in leaf yield (0.76 t ha‐1 and 0.39 t ha‐1) over SCH‐A1 and SCH‐A2, respectively. Only two significant differences in leaf quality index among the nine hybrids and none between TWCHs vs. related SCHs were found. There was a correlation coefficient of 0.98 between leaf yield and monetary value of the crop. Thus, the economic gains recorded for TWCH‐A vis‐à‐vis its SCH counterparts were attributable to increased yield.

Performances of three-way cross hybrids over their respective single crosses and related heterosis of maize (Zea mays L.) hybrids evaluated in Ethiopia

“…Moreover, it was also good for ear height and ear le n gth in Melkassa (H 2 b > 50%). This indicates heritability declines from high favourable to less favourable growing environments for some of agronomic traits and shows a decrease of it from single crosses to three-way crosses [ 18 , 30 ]. If we consider only grain yield for discussion, there was a declining trend of variation for agronomic traits from high land to lowland and similar trend of variation was obtained from single crosses to three-way crosses, this might be due to the genetic mechanism of heterosis potential in single crosses than three-way crosses [ 9 , 20 ].…”

“…The genotype × environment interaction was highly significant for more number of agronomic traits in the single crosses than three-way crosses indicated that the three-way crosses were more stable than single crosses similar to the previous report on sorghum [ 32 ]. This also might be due to the fact that the difference in the genetic mechanism of three-way crosses than single crosses [ 9 , 30 , 42 ]. However, as the genetic background broadness increases, the logic expects superer performance or maximum heterosis for some agronomic traits but the reality resulted in stability than increment.…”

“…Supporting this hypothesis, in the study of use of sister lines in hybrid seed production, the sister lines which had been developed from a two highly related inbred lines (SLs) were suggested as the best strategy for hybrid seed production [ 29 ] when production cost is considered (less acreage required for the production of the same amount of hybrid seed). Moreover, on the comparison study of three-way crosses of tobacco with single crosses, it was reported that the use of three way cross has an economic gain (advantage) [ 30 ]. Furthermore, the evaluation of three-way crosses of Arabica coffee report suggested that three-way crosses better performed as compared to single crosses and checks [ 31 ], and the mid parent heterosis of lint yield was also reported as the advantage of three-way crosses over single crosses [ 28 ].…”