Use of inbred line Secondary traits in predicting performance in Maize(Zea Mays L.)Hybrid under low Nitrogen

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Musonda, Kanyanta LLoyd
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Maize (Zea mays L) is an important multi-purpose staple cereal crop in Zambia.More than 70% of people derive their livelihood from agriculture of which maize production is the major enterprise. Maize production is affected by biotic and abiotic stresses. Most varieties developed in the Zambian National Maize Breeding Programmes have no tolerance to low nitrogen stress. This is so because variety selection is done under optimum N conditions and thereafter released to farmer conditions that are mostly Nitrogen stressed. To predict performance of hybrids on the basis of their inbred lines’, secondary traits of inbred lines were investigated to establish their relationships with grain yield of their respective hybrids under optimum and Low nitrogen levels. Therelationships between hybrid grain yield and yield secondary traits of inbred lines under optimum and Low nitrogen levelswere determined. Yield secondary traits studied included Ears per plant (EPP), Chlorophyll content (CC), Plant height (PH) and AnthesisSilking Interval (ASI).Thirty seven (37) Hybrids, their parents and three local checks (MRI 624, MRI 514 and ZMS 606) were evaluated in a randomised complete block design (RCBD) under optimum and low N conditions at Golden Valley Agricultural Research Trust (GART) Chisamba farm.Under optimum N plant height and Chlorophyll content significantly (45% and 26%, respectively) affected grain yield of inbred lines.For hybrids, plant height and ears per plant had significant influence of 11.4% and 37%, respectively on GY under low N conditions. Also, Plant height had significant influence (35%) on GY under optimum conditions. Plant height and Chlorophyll content of inbred lines had a significant influence of 28 % and 7% respectively on hybrid grain yield. Plant height of inbred lines had a significant influence of 28 % on hybrid grain yield. Indeed,Chlorophyll content showed a significant influence of 7 % of the total variation in Hybrid grain yield. Conclusions were that low N depresses performance, in terms of yield, of both inbred lines and hybrids. The reduction in yield is associated with a reduction in EPP, PH and CC and an increase in ASI. Plant height influenced grain yield of the inbred lines under low N stress conditions. Under optimum conditions it was plant height and CCthat positively influenced grain yield. For hybrids under low N conditions, plant height and ears per plant positively influenced grain yield of the hybrids, while under optimum conditions, only plant height positively influenced grain yield. Under low N conditions, plant height and CCof inbred lines positively influenced hybrid grain yield. Thus,if inbred lines with increased chlorophyll content and plant height under low N are selected, they would give Hybrids with higher yields under small holder farmer conditions which are generally low N conditions in Zambia.
Plant Breeding , Plant genetic Engineering