Sachiko Idota

Effects of Cutting Interval and Cutting Height on Dry Matter Yield and Overwintering Ability at the Established Year in Pennisetum Species

Abstract The effects of cutting interval and cutting height on dry matter productivity and overwintering ability were compared among 4 Pennisetum species, napiergrass, kinggrass, hybrid napiergrass and pearl millet in the established year to examine the suitable cutting practice for the productivity and persistence. The cutting intervals were 60 and 90 days, and the cutting heights were 0 and 30 cm above the ground. Annual herbage dry matter yield (HDMY) was the highest in kinggrass, followed by hybrid napiergrass, napiergrass and pearl millet, and was higher in the plants at a 90-day interval and 0-cm height than at a 60-day interval and 30-cm height, respectively. The percentage of dry matter to fresh matter did not correlate with the annual HDMY or cutting height. The plants cut at a 90-day interval at a 0-cm height had the highest in mean tiller weight, crop growth rate, net assimilation rate and HDMY, but the lowest tiller number and percentage leaf blade to the whole harvested plant. Thus, the correlation coefficients between HDMY and plant characters were positive for plant height, mean tiller weight, leaf area index and crop growth rate in all 4 species and were negative for tiller number and percentage leaf blade except for pearl millet. Both percentage overwintered plants and regrown tiller number were the highest in kinggrass followed by napiergrass and hybrid napiergrass; these were nil in pearl millet under all cutting practices, and were higher in the plants cut at a 30-cm height than at a 0-cm height. This tended to be associated with higher tiller bud number and higher total nonstructural carbohydrate concentration in the stubble after cutting at a 30-cm height. Regrown tiller number was higher in the plants cut at a 60-day interval than at a 90-day interval in all species except for pearl millet, but the percentage overwintered plants was not affected by the cutting interval. Thus, the combination of highest annual HDMY and highest overwintering ability was attained by cutting at a 90-day interval at a 30-cm height in kinggrass.

Dry Matter Productivity and Overwintering Ability of the Dwarf and Normal Napiergrasses as Affected by the Planting Density and Cutting Frequency

Abstract The effects of planting density and cutting frequency on dry matter productivity and overwintering ability were compared in the years following establishment among dwarf varieties (early-heading, DE and late-heading, DL) and normal varieties, Wruk wona (Wr) and Merkeron (Me), in the southern part of Kyushu, Japan. The planting densities examined were high (16 plants m~2, 25 cm X 25 cm of spacing), medium (8 plants rar2,50 cm X 25 cm), and low (4 plants m~2, 50 cm X 50 cm) for Wr, DE and DL, and was only medium for Me. The cutting frequency was three times at about 60-day intervals in 1999 and two times at about 90-day intervals in 2000. Irrespective of the planting density, dwarf varieties were higher in tiller number (TN), leaf area index (LAI) and dry weight percentage of leaf blade (PLB) than normal varieties, but lower in plant height (PLH), mean tiller dry matter weight (MTW) and total dry matter weight at all planting densities in both years. With the increase in planting density, TN and annual herbage dry matter yield (HDMY) increased. The annual HDMY was higher in 2000 (cut twice) than in 1999 (cut three times), and the difference in annual HDMY between the dwarf and normal varieties was reduced by planting at a high density and cut twice. This was due to higher MTW in dwarf varieties than in normal varieties at the higher TN conditions. The percentage of overwintered plant (POP) tended to be higher in DL than in other varieties and was higher in 2000 than in 2001 for all varieties, while it tended to decrease with the increase in planting density. Even though the dry matter productivity was higher in the normal varieties than in the dwarf varieties at any planting density and cutting frequency, DL tended to show a stable productivity with high PLB irrespective of planting density and cutting frequency. In addition, it had a high overwintering ability compared with the other varieties.

Cadmium Phytoremediation Potential of Napiergrass Cultivated in Kyushu, Japan

Napiergrass (Pennisetum purpureum Schumach), a C4 tropical species, has been used for forage since it has high dry matter productivity, sustainability over several years in low-altitudinal sites of Kyushu, and little damage from serious pests. Recently, this grass has gained attention due to its potential as a bioethanol feedstock and for phytoremediation. Napiergrass cultivar Wruk Wona was grown as an annual crop in cadmium- (Cd-) contaminated soils under two cutting frequencies. Annual dry matter yield was not affected significantly by cutting frequency, but the concentration and uptake of Cd were higher when cut twice rather than only once, due to high Cd content of the herbage from the second cutting. Therefore, the soil Cd concentration was reduced by 4.6% when managed by cutting twice in a single year of Napiergrass cultivation.

Triple Cropping Systems of Spring Maize, Tropical Grass of Teff (Eragrostis tef) and Winter Cereal Crops to Combine Total Digestible Nutrient Yield with Protein Concentration in Southern Kyushu, Japan

It is ordinarily common for forage production in southern Kyushu to adopt a double cropping system, composed of summer forage crops (e.g. maize and sorghum) cultivated from late March to early September, and winter grass crops (e.g. Italian ryegrass (IR) and oat) from mid-October to the following May. However, if high total digestible nutrient (TDN) production is aimed to introduce winter cereal crops (e.g. wheat and barley) as a replacement of IR, it is necessary to cultivate tropical grass, which has a rapid-growth potential with high crude protein (CP) concentration in a switching period between summer and winter crops. In this study, teff (Eragrostis tef) was tried to evaluate as a candidate crop in the switching period. Yield and quality of two types of triple forage cropping system were determined under maize-teff-barley and maize-teff-wheat in the first and second year, respectively. Compared with the normal year, summer temperature was higher and summer and winter precipitations were lower in the first year, while no climatic disorder was observed in the second year. Even though dry matter yield of teff was minimal in the present system due to weed damage, CP concentration was the highest among crops and TDN yields of the present cropping system tended to be higher in the second year with no drought stress than in the conventional maize-IR system in the region.

Genotypic differences in forage quantity and quality of canopy strata in napiergrass (Pennisetum purpureum Schumach)

To assess grazing suitability of napiergrass genotypes across real dwarf Taiwan 7734 (7734), semidwarf (DL) and normal-tall Merkeron (ME), yield and quality attributes were determined in canopy strata. Plant densities of 7734, DL, and ME were 4, 2, and 1 plants m -2 , respectively, and relative light intensity (RLI) and dry weight of plant fractions were obtained by stratified clipping at the first and second cuttings in early September and late November, respectively. Results of this study revealed that plant height was in the order of ME (199 cm), followed by DL (128 cm) and 7734 (88 cm) at the first cutting, and 7734 tended to have higher tiller density, dry matter yield, and leaf area index than DL and ME at both cuttings. Canopy RLI in 7734 tended to decrease higher with strata than in DL and ME, which was corresponded with the lowest K in 7734, followed by DL and ME at both cuttings. Genotype 7734 had the highest digestibility and crude protein concentration, and lowest structural carbohydrate concentrations across genotypes, which would be favorable to grazing use by breeding beef cows. Mohammad Hamid Kadwal 1 , Yasuyuki Ishii 2,* , Yusuke Iki 3 and Sachiko Idota 2

Adaptability of Napiergrass (Pennisetum purpureum Schumach.) for Weed Control in Site of Animals Buried after Foot-and-Mouth Disease Infection

After the infection of foot-and-mouth disease outbreaks in Miyazaki, Japan, in 2010, cattle and swine were slaughtered and buried in a site of 100 ha, where weed control is difficult and costly since lands are unlevelled and prohibited to be plowed for 3 years. To consider the adaptability of napiergrass (Pennisetum purpureum Schumach.) to the animal burial site for weed control, two napiergrass varieties, normal Wruk wona (WK) and dwarf late-heading variety (DL), were transplanted, compared with sowing of maize (MZ) and sorghum (SR) in both burial (BU) and neighboring bordered area (BO) in mid-June 2011. Even though several weed control methods were subjected to lands, MZ and SR failed to be established stably at only 1/3–1/2 due to the suppression of growth by indigenous weeds, while WK and DL successfully established as high as 82–91% and 73–85%, respectively, in 2011. The poor establishment of MZ and SR after sowing tended to be increased with the year from establishment. Plant dry matter yield and cellulose concentration were the highest in WK in 2011, while overwintering ability was constantly higher in DL in the 3 years. It is necessary to consider the utilization of forage plants on the animal burial site.