Frequency distribution and mean comparisons of red light absorbance-transmittance of the e1 leaf sectors of five pipeline maize hybrids during early grain filling in subtropical winter
Authors: Adhikari Nav Raj , Ghimire Surya Kant , Sah Shrawan Kumar , Koirala Keshab Babu 
Published: January 2018

Background: Crop scientist’s curiosities were to examine variation in photosynthetic sectors of grain filler leaf or flag leaf of any major crop species. Crop scientists including plant breeders too will be privileged from the findings. So it includes such precision evaluation of five single cross pipeline hybrids (Hs 6, 112, 14, 113 and 109) of yellow maize using red light absorbance-transmittance (RAT) measure by chlorophyll meter SPAD 502 before their release as cultivars. Materials and methods: For it, five pipeline hybrids were examined from two RCBD trials that they were in a big research plot with uniform soil fertility level and with the same control environment. Each of the trials was conducted planting the seeds of the fifteen newly bred separate hybrids on October 3, 2012 exposing their flowering and early grain filling to the natural winter in the subtropical region in Nepal. Five plants of the pipeline hybrids of the fifteen plots of three replications were randomly selected and tagged before tassel emergence. After about one month of anthesis, one hundred observations of the RAT SPAD measures were taken from the chlorophyll meter from the just-above-ear (e1) leaf of each of the selected plants of the hybrids of 180 to 185 days of crop maturity in three days from 99 to 101 days after sowing (DAS). Results and discussion: From analysis of frequency distribution of the RAT SPAD measures of the e1 leaf sectors, it is not necessary that hybrids that demonstrates curve with high kurtosis and high RAT SPAD measures always yield higher. Among the five hybrids, second highest grain yielding hybrid 112 had least leaf sectors of very low RAT SPAD measures. Besides, the hybrid 112 has been found least skewed and least peaked among the five hybrids. Furthermore, the hybrid 112 displayed least coefficient of variation and standard deviation among the 1500 RAT SPAD readings of its e1 leaf sectors. From the mean analysis through DMRT (Duncan Multiple Range Test), the twenty four averages have been found almost non-significant different among themselves inside each of the five hybrids. Single reading and four reading averages were non-significant different to one hundred reading average of each of the fifteen selected plants. Besides, the study also implies that a single reading from a leaf in the surrounding region of the topmost ear in five randomly selected plants can suffice to reflect the average SPAD measure of the particular leaf if the readings are from the e1 leaf. But, it can also be concluded that the similar non-significant nature of average central leaves around the top ear node. The mean comparison also gives useful information about the methodology of taking SPAD observations and how many readings are enough for the study of RAT, chl and N concentration in maize leaves. The paper includes logic of taking e1 leaf for RAT SPAD observations in discussion section.