Kernel Water Content Research Articles

EFFECT OF KERNEL WATER CONCENTRATION AT HARVEST AND DRYING METHOD ON GRADES OF RED SPRING AND DURUM WHEATS

Effects of kernel water concentration at harvest, and windrow compared to artificial drying, were determined in two red spring (Triticum aestivum L.) and three durum (T. turgidum L. var. durum) cultivars. Grain harvested at kernel water concentrations of 1000 to < 170 g water per kilogram kernel dry weight was dried in the field in simulated windrows or artificially in a forced-air oven (40–45 °C). Test weight and commercial grades were determined. Artificial drying of immature wheat reduced grades, primarily due to numbers of green kernels. Green kernel levels reduced grades of windrowed durum wheat in 1 of 3 years. In the absence of grade-limiting levels of green kernels, test weight limited grades of durum in 1 year, particularly in the windrowed treatment. In a separate experiment, percentages of green kernels were determined in field-scale windrowed and standing hard red spring and durum wheat crops. Levels of green kernels declined at similar rates in standing and windrowed crops. The kernel water concentration at which level of green kernels dropped to 0.75%, the maximum level tolerated in the top grades of hard red spring and durum wheat, was lower in dry years when maturity was forced than in moist years.Key words: Wheat (red spring), wheat (durum), windrowing, artificial drying, test weight

Harvesting Losses of Spring Wheat in Windrower/Combine and Direct Combine Harvesting Systems1

AbstractHarvest loss of cereal crops has been reported to be reduced by windrow‐drying prior to combing compared to direct combining, but few comparisons of the two systems have been made. Field studies were conducted in order to compare harvesting losses of five wheat (Triticum spp.) cultivars of varying shattering resistance in direct combine and windrower/combine harvesting systems on a Swinton loam soil (Aridic Haploboroll). Cutting treatments were initiated when kernel water concentration was about 670 g water per kg kernel dry weight and continued for at least 2 weeks after kernel water concentration reached 170 g kg−1. Natural shattering losses and cutting losses were measured at each cut; combine pick‐up losses were measured when the windrows were combined. Cutting and pickup losses did not change with cutting time and there was no consistent variation among cultivars. Cutting losses ranged from 0.75 to 3.03 g m−2; pick‐up losses ranged from −0.10 to 0.98 g m−2. Natural shattering losses varied with cultivar and year; cummulative loss ranged from a low of 4 to a high of 27 g m−2 over a period to some 2 weeks after kernel water concentration reached 170 g kg−1. Harvesting losses were similar for the two harvesting systems for cultivars resistant to shattering, but greater for the direct combine than for the windrower/combine system for cultivars susceptible to shattering. An earlier start to direct combining (at kernel water concentrations of 170 to 250 g kg−1) narrowed the difference between the systems for cultivars susceptible to shattering as did delayed windrowing.

EFFECT OF HARVEST TIME AND DRYING METHOD ON QUALITY AND GRADE OF SPRING TRITICALE

Two spring triticale (X-Triticosecale Wittmack) cultivars, Carman and Welsh, and one advanced-generation breeding line were grown under field conditions for 3 yr to study the effects of harvest time and drying method on quality and grade. Plots were harvested at six to seven intervals when kernel water concentration was in the 1000 to 100 g water per kilogram kernel dry weight range. Grain was dried in the field in simulated windrows or artificially dried in a forced-air oven at 40–45 °C. Test weight, 1000-kernel weight, falling number, germination, and commercial grade were determined. Test weight increased with decreasing kernel water concentration at harvest, particularly in the artificially dried treatment. Test weight was greater in the windrowed than in the artificially dried treatment, especially for harvests made at high water concentrations. Harvest at high kernel water concentrations tended to reduce 1000-kernel weight, more so in the windrowed than in the artificially dried treatment. Although falling numbers were influenced by harvest time and drying method, there were no clear trends. Germination was reduced in material cut at a kernel water concentration above 680 g∙kg−1 in 1 of 2 years. Grades were reduced by artificial drying of grain, particularly when harvested at high kernel water concentrations. Grades were unaffected by windrowing at kernel water concentrations of up to 1000 g∙kg−1.Key words: X-Triticosecale Wittmack, test weight, falling number, germination, windrow

Rate and Duration of Growth of Kernels Formed at Specific Florets in Spikelets of Spring Wheat1

In an earlier study, large differences in individual kernel weight were observed within spikelets of spring wheat genotypes (Triticum aestivum L. em Thell). To account for these differences, growth rates and effective filling periods were measured in field experiments for kernels formed at each floret position in central spikelets. The genotypes ‘Era’, ‘8037’, and ‘72316’, which differed in kernel weight and kernel number per spikelet, were used. Kernels formed in the fourth and fifth florets (numbered from the spikelet base) displayed significantly lower growth rates than proximal kernels during the period of linear kernel dry matter accumulation. Kernel growth rates during this period over all years, genotypes, and floret positions were significantly correlated with final individual kernel weights.Another factor that influenced kernel weight within a spikelet was the earlier occurrence of anthesis in the proximal florets compared to distal ones. Kernels formed in proximal florets already had a considerable weight advantage even before the period of linear dry matter accumulation. Effective filling period durations of proximal kernels of Era and 72316 were longer, a probable consequence of the earlier anthesis in these florets. Cessation of dry matter accumulation (and the associated sharp decline in kernel water content) were judged to occur at approximately the same time for all kernels in a spikelet. Additional research oriented toward understanding those factors responsible for establishing kernel growth rate during the linear dry matter accumulation period is advocated.