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1.
M. Lafarge 《Grass and Forage Science》2006,61(2):182-191
The effects of sward age and fertilizer‐nitrogen (N) application rate on reproductive tillers and their involvement in the dynamics of swards of perennial grasses were investigated using sown swards of tall fescue (Festuca arundinacea). Treatments included plots representing two sward ages (two and six‐year‐old swards) and two fertilizer‐N rates (150 and 350 kg N ha?1 yr?1) on the same experimental field. In each of 2 years all plots were cut at the silage stage and three times afterwards. After each cut, during two growing seasons, the vegetative tillers and stubs of cut reproductive tillers were counted in ten permanent quadrats for each of the four treatments, using a grid of 150 cells, each of 2 cm × 2 cm. The results showed a higher density, and a greater proportion of reproductive tillers, on the higher fertilizer‐N rate treatment and on the older swards. The density of vegetative tillers was found to be greater in close proximity to the reproductive tillers in all sward treatments and in both assessment years. Thus, cutting the reproductive tillers did not result in thinning of the swards. It is suggested that a mother‐tiller effect, enhancing renewal of tillers, was likely, although zones bearing reproductive tillers during the second spring were sometimes already denser than zones in the rest of the quadrats before the winter. 相似文献
2.
I. Bahmani C. Varlet-Grancher L. Hazard C. Matthew M. Betin A. Langlais G. Lemaire & E. R. Thom 《Grass and Forage Science》2000,55(4):367-371
Post-flowering tillering responses of 'Ellett' and 'Grasslands Ruanui' perennial ryegrass ( Lolium perenne L.) cultivars after inflorescence production were studied at INRA, Lusignan in France, at near ambient light (absence of light competition, control treatment) and under shading (low-light intensity and low red–far red ratio). A dense sward containing inflorescence bearing plants of both perennial ryegrass cultivars at ambient light was cut to a height of 50 mm above ground level after which the light treatments were imposed. Forty-five days later, data were collected on the number of tillers per plant, the number of new tillers per original tiller and the dry weight of vegetative and reproductive tillers. Regardless of light treatment, cv. 'Ellett' had fewer tillers per plant, higher weight per tiller and a higher proportion of reproductive tillers than did cv. 'Grasslands Ruanui'. Number of tillers per plant and number of new tillers per tiller were consistently reduced under shade compared with the control treatment for both cultivars. When shaded, weight of reproductive tillers of cvs 'Ellett' and 'Grasslands Ruanui' were 40% and 43%, respectively, less than the control, whereas vegetative tiller weight did not change. In addition, differences between cultivars in the tillering strategy after flowering seem to be unaffected by the light environment. Thus, field observations regarding tillering of cvs 'Ellett' and 'Grasslands Ruanui' were consistent with current results suggesting different grazing managements are needed after flowering to optimize the replacement of tillers for both cultivars. 相似文献
3.
The effect of defoliation on the vegetative, early reproductive and inflorescence stages of tiller development, changes in the dry‐matter yield of leaf, stem and inflorescence and the associated changes in forage quality was determined on plants of annual ryegrass (Lolium rigidum Gaud.) and Italian ryegrass (L. multiflorum Lam.). The field study comprised seventy‐two plots of 1 m × 2 m, sown with one annual ryegrass and seven Italian ryegrass cultivars with a range of heading dates from early to late; defoliation commenced 6 weeks after germination. During the vegetative stage of growth, plots were defoliated when the tillers had three fully expanded leaves (three‐leaf stage). During the early reproductive stage of growth, to simulate a cut for silage, plots were defoliated 6–7 weeks after 0·10 of the tillers displayed nodal development. The subsequent regrowth was defoliated every 3 weeks. Assessments of changes in tiller density, yield and quality were made in the growth cycle that followed three contrasting cutting treatments during the winter–spring period (from 10 July). In treatment 1, this growth cycle (following closing‐up before a subsequent conservation cut) commenced on 7 August following two defoliations each taken when the tillers were at the three‐leaf stage. In treatment 2, the growth cycle commenced on 16 October following: for early‐maturing cultivars, two cuts at the three‐leaf stage, a cut for silage and an additional regrowth cut; for medium‐maturing cultivars three cuts at the three‐leaf stage and a cut for silage; and late‐maturing cultivars, five cuts at the three‐leaf stage. In treatment 3, defoliation up to 16 October was as for treatment 2, but the growth cycle studied started on 27 November following two additional regrowth cuts for early‐ and medium‐maturing cultivars and cut for silage for the late‐maturing cultivars. Tiller development for all cultivars was classified into three stages; vegetative, early reproductive and inflorescence. In treatment 1, in vitro dry‐matter digestibility (IVDMD) and crude protein (CP) content were negatively associated with maturation of tillers. IVDMD ranged from 0·85 to 0·60 and CP ranged from 200 to less than 100 g kg–1 dry matter (DM) during the vegetative and inflorescence stages respectively. This large reduction in forage quality was due to an increase in the proportion of stem, inflorescence and dead material, combined with a reduction in the IVDMD and CP content of the stem. A high level of forage quality was retained for longer with later‐maturing cultivars, and/or when vegetative tillers were initiated from the defoliation of early reproductive tillers (treatments 2 and 3). However, 15 weeks after the closing‐up date in treatment 1, defoliation significantly reduced the density of inflorescences with means (±pooled s.e_m.) of 1560, 1178 and 299 ± 108 tillers m–2, and DM yield of inflorescence with means of 3·0, 0·6 and 0·1 ± 0·15 t ha–1 for treatments 1, 2 and 3 respectively. This study supports the recommendation that annual and Italian ryegrass cultivars should be classified according to maturity date based on the onset of inflorescence emergence, and that the judicious defoliation of early reproductive tillers can be used to promote the initiation of new vegetative tillers which in turn will retain forage quality for longer. 相似文献
4.
O. R. Jewiss 《Grass and Forage Science》1972,27(2):65-82
Tillering is examined in relation to the morphology and habit of growth of the perennial herbage grasses; particular reference is made to the effects of cutting and grazing. The importance of tillering in establishment and regeneration or perennation of a grass sward is considered; greater importance is attached to the role of tillers in the regrowth of swards cut for conservation at the reproductive stage of growth. Amounts of regrowth are related to both the number and size of vegetative tillers present at the base of reproductive tillers at the time of cutting. The probable inhibition of the replacement tiller buds by the developing inflorescence is suggested as a reason for the poor growth of grass swards in the favourable environment of midsummer. The physiological mechanisms which control tillering during reproductive development are examined. Spring and winter wheat (Triticum aestivum), Lolium temulentum and Phalaris tuberosa are used as physiological tools to demonstrate that tillering is restricted during reproductive development, and that stem extension may be more important than changes at the stem apex in controlling this restriction of tillering at the base of the inflorescence-bearing stem. It appears from results of the application of a range of growth regulators that substances derived from the meri-stematic centres, in either the elongating stem or the terminal meristem, indirectly control the metabolic activity of the lateral buds from which new tillers are derived. The degree of apical dominance is shown to depend on the light intensity in which the plants are grown. Finally, the physiological results are used to suggest reasons for the commonly found apparent inability of heavily fertilized perennial ryegrass (Lolium perenne) swards to regrow after cutting at the inflorescence-emergence stage of growth. 相似文献
5.
为了解不同类型小黑麦冠层结构及产量构成差异,以加工型品种东农8809、饲用型品种东农5305和粮饲兼用型品种东农96026为材料,采用随机区组设计,探讨了三种类型小黑麦主要生育阶段的平均叶倾角、天空散射辐射透过率、太阳直射辐射透过率、消光系数和叶面积指数的特点。结果表明,加工型品种东农8809的消光系数小,生育后期叶倾角过大,出现漏光现象,这种不合理的冠层结构造成太阳辐射的浪费,使籽粒产量形成受到限制;饲用型品种东农5303的平均叶倾角在营养生长阶段最大,孕穗期降低,营养生长阶段较合理的冠层结构成为其较高叶面积指数形成的基础;粮饲兼用型品种东农96026的平均叶倾角、天空散射辐射透过率和直接辐射透过率均小,消光系数大,冠层结构合理,对光的截获能力强,籽粒产量最高。 相似文献
6.
Field experiments were conducted in Bhubaneswar, Orissa, India, during the dry season (January–May) in 2008 and 2009 to investigate
whether practices of the System of Rice Intensification (SRI), including alternate wetting and drying (AWD) during the vegetative
stage of plant growth, could improve rice plants’ morphology and physiology and what would be their impact on resulting crop
performance, compared with currently recommended scientific management practices (SMP), including continuous flooding (CF)
of paddies. With SRI practices, grain yield was increased by 48% in these trials at the same time, there was an average water
saving of 22% compared with inundated SMP rice. Water productivity with AWD-SRI management practices was almost doubled (0.68 g l−1) compared to CF-SMP (0.36 g l−1). Significant improvements were observed in the morphology of SRI plants in terms of root growth, plant/culm height, tiller
number per hill, tiller perimeter, leaf size and number, leaf area index (LAI), specific leaf weight (SLW), and open canopy
structure. These phenotypic improvements of the AWD-SRI crop were accompanied by physiological changes: greater xylem exudation
rate, crop growth rate, mean leaf elongation rate (LER), and higher light interception by the canopy compared to rice plants
grown under CF-SMP. SRI plants showed delayed leaf senescence and greater light utilization, and they maintained higher photosynthetic
rates during reproductive and grain-filling stages. This was responsible for improvement in yield-contributing characteristics
and higher grain yield than from flooded rice with SMP. We conclude that SRI practices with AWD improve rice plants’ morphology,
and this benefits physiological processes that result in higher grain yield and water productivity. 相似文献
7.
A. S. Laidlaw 《Grass and Forage Science》2005,60(2):200-209
The relative contribution of tillers present in April and those appearing in consecutive periods in spring was assessed for perennial ryegrass cultivars in the three maturity groups (early, intermediate‐ and late‐heading). Each group was represented by two diploid and one tetraploid cultivar each in plots in their third (2000) and fourth (2001) harvest years in three replicated blocks receiving an average of 325 kg N ha?1 and cut seven (in 2001) or eight (in 2000) times annually. ‘Main’ tillers and their daughters were marked with colour‐coded PVC‐covered wire loops in early April as were daughters which appeared in consecutive periods between harvests, the loop colour identifying the period of origin of the tiller. Tillers were harvested at cutting height (5 cm) before the plots were harvested and the herbage from tillers with the same colour code bulked per plot. Tillers were identified retrospectively as ‘reproductive’ if they had been decapitated at the previous harvest. Dry‐matter yield was higher in the early than late‐heading cultivars in April and early May but this was reversed in harvests in late May and June. The early heading group had a lower lamina content than the late‐heading group during reproduction growth, both due to the reproductive tillers (mainly those which overwintered) having a lower leaf content and to their being fewer and smaller vegetative tillers during the reproductive phase than for the late‐heading group. Turnover of tillers was high in spring due to decapitation of reproductive tillers and rapid post‐flowering tillering. This was particularly pronounced in the early heading group which also had slightly more tillers marked in April which were subsequently decapitated than in the other maturity groups, i.e. 0·56 compared with 0·44 for the late‐maturing group. Mean ratios of rate of death: rate of tillering for 3 years (1999–2001) for the early and late‐heading groups were 0·8 and 0·4, respectively, for April–May and 1·1 and 2·4, respectively, for June indicating the different patterns in tiller turnover for the two extreme maturity groups. Information on tiller origin and contribution to yield can be used to refine tiller‐based grass growth models. 相似文献
8.
This study was conducted to determine effects and interactions of plant density on digestibility and plant morphology of diverse orchardgrass ( Dactylis glomerata L.) clones. Propagules of ten orchardgrass clones with contrasting morphology from two maturity groups (inflorescence emergence differed by 8d) were evaluated in sward (0·15-m centres) and spaced (0·60-m centres) plantings. Plants were harvested from spring growth on a common date near anthesis and from summer growth when about 5 weeks of forage growth had accumulated. The plants were separated into morphological parts before measuring their size and in vitro digestible dry matter (IVDDM). There were few plant density × orchardgrass clone interactions, and correlation coefficients of clones grown at the two plant densities generally were high (e.g. 0·87 in spring and 0·67 in summer for IVDDM of total herbage). Plant density had little effect on morphology of leaf blades from reproductive tillers, but leaf blades of vegetative tillers were 12% (spring) and 22% (summer) longer from sward than from spaced plantings. Moreover, reproductive tillers were 26% taller in sward than in spaced plantings. Also, leaf blades of vegetative tillers in spring growth were more than twice as long, of similar width and 65% thicker than leaf blades from reproductive tillers. Because divergent genotypes respond similarly to plant density, it is concluded that observations taken in spaced plantings of orchardgrass can be used to make inferences about relative differences in sward plantings for the traits studied. 相似文献
9.
LEWIS JONES 《Grass and Forage Science》1979,34(2):139-144
The drying of Italian ryegrass (RvP) tillers under controlled conditions at three stages of growth is described. The rate of water loss was dependent on tiller morphology as well as on water content. Leaf laminae dried faster than stems and also aided the loss of water from stems. Drying time was shortest for vegetative tillers despite their high water content, and longest for reproductive tillers shortly before ear emergence. The practical implications in relation to haymaking are discussed. 相似文献
10.
Natural diversity in vegetative and reproductive investments of perennial ryegrass is shaped by the climate at the place of origin 
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下载免费PDF全文 P. Barre T. Ruttink H. Muylle P. Lootens J.‐P. Sampoux A. Rohde D. Combes I. Roldán‐Ruiz 《Grass and Forage Science》2018,73(1):193-205
In forage grasses, vegetative and reproductive investments are major determinants of yield and persistence. A survey of the diversity of vegetative and reproductive investment traits was carried out on 213 perennial ryegrass genotypes, representing 51 natural European accessions. Plants were phenotyped for traits related to leaf elongation, tillering, reproductive investment and heading date, at two locations with markedly different climates. Strong genetic effects for all traits were found. Interactions between genotype and location were moderate. Plants showed stronger spring leaf growth, lower numbers of tillers and higher reproductive investments at Lusignan (France) than at Melle (Belgium). Plant growth rate and tillering capacity were genetically nearly independent suggesting breeding for both traits simultaneously and independently should be possible. A high genetic diversity was observed for all traits. This diversity was structured in three main clusters. One cluster comprised early‐flowering genotypes with high reproductive investments and high spring growth rates. The remaining genotypes fell into two clusters based on differences in tillering capacity. Clear links were found between traits and the climatic conditions of the region of origin of the accessions. Autumn growth rate was positively correlated with solar radiation at the region of origin in October and February. 相似文献
11.
Takemasa Koumoto Naoko Saito Naohiro Aoki Toshiki Iwasaki Shigenao Kawai Shuji Yokoi 《Plant Production Science》2016,19(4):497-507
We tested whether exposing rice plants to abiotic stress (salt or shade) during vegetative growth affects the chilling tolerance of reproductive organs, which is one of the most important traits for rice growing in a cool climate; we used two rice cultivars with different tolerance in two growing seasons. We divided the vegetative growth into three phases to clarify the most sensitive period: 7–22 days after transplanting (DAT), 23–38 DAT and 39–54 DAT. Chilling tolerance of the pre-stressed plants was based on the male sterility induced by low temperatures. Shade and salt stress during all three vegetative growth phases significantly reduced stomatal conductance. Shade decreased the specific leaf weight and the leaf sugar and starch contents, but salt had no significant effect, despite causing leaf damage. Low temperatures during the reproductive stage induced spikelet sterility in all plants, but the magnitude was greater in the salt- and shade-stressed plants of both cultivars, especially those stressed late during vegetative growth. The increased spikelet sterility caused by chilling was closely related to the reduction of the total spikelet number per panicle. This is the first study to show that salt and low light stress during vegetative growth increased the susceptibility of rice plants to chilling damage during panicle development. 相似文献
12.
The fertile tiller production and seed yields of spaced plants of meadow fescue varieties were found to vary widely with the time of sowing, particularly in the first harvest year. The benefit of early spring sowing is indicated in the total productivity over two harvest years.
Varieties differed in the amount of heading in the seeding year; the American type was the most prolific. This had a bearing on the relative yields in the first harvest year, since many of the potentially productive tillers of this variety were wasted through the plants becoming ripe to flower in the seeding year and, therefore, the rate of tiller production was checked. Competition within the plant appeared to be the cause of tillers remaining vegetative when conditions otherwise seemed suitable for generative development. The smaller-sized plants gave a higher proportional increase of fertile tillers at harvest than would be expected from the vegetative tillers counted in April, while at the same time there was a negative relationship at harvest from plants which had a very high number of vegetative tillers.
Infertility as reflected in a poor seed set at the time of harvest is a serious wastage of potential production in meadow fescue and, in selecting for superior seed output, breeders need to take this factor into consideration.
The 1000-seed weight varied between varieties, the pasture type being inferior to the two hay types. 相似文献
Varieties differed in the amount of heading in the seeding year; the American type was the most prolific. This had a bearing on the relative yields in the first harvest year, since many of the potentially productive tillers of this variety were wasted through the plants becoming ripe to flower in the seeding year and, therefore, the rate of tiller production was checked. Competition within the plant appeared to be the cause of tillers remaining vegetative when conditions otherwise seemed suitable for generative development. The smaller-sized plants gave a higher proportional increase of fertile tillers at harvest than would be expected from the vegetative tillers counted in April, while at the same time there was a negative relationship at harvest from plants which had a very high number of vegetative tillers.
Infertility as reflected in a poor seed set at the time of harvest is a serious wastage of potential production in meadow fescue and, in selecting for superior seed output, breeders need to take this factor into consideration.
The 1000-seed weight varied between varieties, the pasture type being inferior to the two hay types. 相似文献
13.
The causes of tiller death in a 2-year-old perennial ryegrass sward were examined between April and August 1977. Physiological causes accounted for most tiller deaths and grazing by slugs and rodents was more important than the damage caused by stem-boring larvae. Tillers which died were mainly small and vegetative, although some flowering tillers died prematurely. Low nutrient status delayed but did not prevent tiller death. Using 14CO2 it was shown that small tillers fixed relatively less radiocarbon than did larger tillers and they did not receive much support for their carbon economy. Selective defoliation showed that in April defoliated tillers imported radiocarbon from undefoliated tillers but that in July at anthesis an undefoliated reproductive tiller retained most of the carbon it fixed, despite its vascular association with defoliated tillers. It appears that much of the tiller death during the period April-August is due to the failure of the more favourably placed tillers to support other tillers which are heavily shaded. 相似文献
14.
籼粳亚种间杂交稻甬优6号超高产株形特征与竞争优势分析 总被引：10，自引：2，他引：10
2003-2005年的试验结果表明,与常规晚粳稻秀水63和籼型杂交晚稻汕优63相比,三系籼粳亚种间杂交晚粳稻甬优6号的超高产与其生育期间株形特征及竞争优势密切相关。生育前期,甬优6号的分蘖数介于籼、粳稻之间,消长平稳,分蘖力中等,无效分蘖少;生育中期,植株的茎、鞘、叶生长快,生物量大,上3叶长而内卷挺立,群体上下受光态势好;生育后期,植株高大,茎秆粗壮,鞘叶长而抱秆紧密,茎基部节间短而厚重;成熟期,穗呈弧形,一、二次枝梗数特别多,粒多穗重,着粒密度适中,粒形偏团;各生育阶段的根冠比高。另外,对籼粳亚种间超级杂交稻的理想株形进行了讨论。 相似文献
15.
宽幅麦套花生与小麦有较长共生期,其生长发育有前期晚发、后期缓降和中期猛增的特点。生育中期猛增是干物质累积的关键,此阶段(始花后80天)中所累积的干物质量,占全生育期累积总量的87.6％,是转换成经济产量的基础。在收获前40天内荚果增长量,占荚果产量的68.6％。采取用养结合集约耕作施肥一体化;良种配套充分利用光热资源;改变种植方式发挥边际优势;规范种植;早套覆膜严把播种质量关;根据生长特点加强促保管理等配套技术,实现小麦花生双300—400公斤。 相似文献
16.
《Field Crops Research》1987,17(2):163-173
The relative sensitivity to water stress at different growth stages of goosegrass (Eleusine indica (L.) Gaertner) was investigated by measuring water status and growth of groups of plants stressed during the vegetative stage, the reproductive stage, and during both stages. Plants were grown from seed in large pots in a controlled-environment chamber at 29/23°C and 14-h photoperiod. In all treatments, decreasing leaf water-potential was correlated with decreasing osmotic and pressure potentials. Plants stressed during the flowering stage maintained greater pressure potentials at any leaf water-potential than plants stressed during vegetative growth or stressed twice. Prestressing the plants did not induce lower leaf osmotic potentials at full turgor. However, dehydration was the main cause of low osmotic potentials measured in the leaves of the plants stressed twice. Stomatal closure occurred over a relatively large range of leaf water-potentials. The sensitivity of stomata to water stress in this species was fairly similar in the two growth stages studied. Leaves of plants stressed during the flowering stage had a smaller decline in total biomass during the stress period, and a higher rate of growth after rewatering, compared to the plants that received a stress during vegetative growth and flowering or were stressed during vegetative growth. 相似文献
17.
《Field Crops Research》1987,17(2):121-140
Identification of the key physiological traits that limit carbon and nitrogen accumulation in grain legumes is an important step in understanding how to improve their productivity in water-limited environments. A growth model was used to assist in the interpretation of two field experiments comparing the performance of soybean, cowpea and black gram under water deficits, and to assess the importance of different physiological traits in determining productivity in these grain legumes. The coefficients of the relationships in the model describing leaf growth, carbon and nitrogen input, seed growth, and the water budget were obtained from the literature and from glasshouse and field experimentation.The principal differences in input variables to model the growth of soybean, cowpea and black gram were those describing leaf emergence rate, N fixation during seed filling, and the biochemical composition of the seeds. The relationship describing the response of leaf-area growth, radiation-use efficiency and N fixation to soil water content differed little among species. Similarly, those input variables associated with radiation interception and solar radiation-use efficiency were held constant for the three species.An important difference among the species was that N fixation continued during seed growth in soybean but did not in cowpea or black gram. As N is translocated from vegetative tissue to developing seeds, the absence of N fixation during seed-filling results in a more rapid decline in canopy photosynthetic capacity, thus limiting the potential productivity of cowpea and black gram. The study also highlighted the importance of the delay in reproductive development in cowpea and black gram in response to water deficits. The tendency for cowpea to yield higher under water-limited conditions was more closely related to the ontogenetic flexibility of the species than to any other physiological traits or response. 相似文献
18.
A study over two years involving tiller identifica tion according to month of origin enabled the contribution of individual tillers of perennial rye grass Grasslands Ruanui, timothy Grasslands Kathu and a local New Zealand strain of prairie grass (Bromus unioloides) to be determined at seed harvest. In addition, the distribution of seed-heads in different arbitrary emergence groups was detemined so as to allow analysis of individual seedhead components within each group. In all species, tillers formed during the first 4 months following an autumn sowing in the first year, and also in the immediate post-harvest period and through the autumn in the second year, made a major contribution to seedhead numbers and seed yield at harvest. These tillers had a lower vegetative mortality rate than those formed in the spring. Primary tillers formed after sowing were highly persistent and became almost exclusively repro ductive. Many vegetative tillers died before har vest, behaving as annual tillers. Spring-formed tillers made a major contribution to the vegetative growth of the plant over the summer and early autumn. These tillers generally died before the following winter. Tillers formed in winter and early spring by ryegrass and prairie grass showed a high mortality, particularly in the second year. In timothy, mortality was highest amongst tillers formed in late spring. The reduced contribution of spring-formed tillers to the seed head population occurred as a result of fewer heads numerically compared with older tillers. In all species, most seedhead components varied according to time of ear emergence. Early emerged heads were generally longer, bore more spikelets and more florets per head and had a greater culm length than late-emerged heads. The major trend in all species was a general depression in head length, spikelet and floret number and culm length with grazing. These effects were in most cases partly or completely overcome by N application. The major effect of applied N was to increase floret number per head. 相似文献
19.
通过对内蒙古海拉尔地区春油菜结角层的研究,分析了结角层中角果组成,分布及其性状的变化,结果表明:1、春油菜结角层较薄,PAI较小,提高产量主要是控制下位分枝的生长,改善结角层内部的光照条件,形成一个高光效的结角层结构。群体直立不倒,各枝序排列有序。2、提高结角层生产力的关键是在结角层的纵向上提高千粒重、横向上增加角粒数。3、各枝序的生产力与它们的结角起止高度密切相关。 相似文献
20.
We examined the effect of twice harvesting of forage rice with the first harvest at the full heading stage on total dry matter yield in the cultivars Taporuri, Mohretsu, and Hinohikari and in line Saikaishi 253 in southwestern Japan. Taporuri produced the highest total dry matter yield, with a value 60% higher than that of Hinohikari. The first crop of Taporuri had a longer duration of vegetative growth than those of Mohretsu and Hinohikari, and had the highest dry matter yield because of its greater weight per tiller than Hinohikari and its more tillers per square meter than Saikaishi 253, which had a similar duration of vegetative growth. The second crops of Mohretsu, Taporuri, and Saikaishi 253 had longer vegetative growth and higher dry matter yields than Hinohikari. Dry matter yields of both crops were closely related to the duration of vegetative growth and the weight per tiller, but not to tillers per square meter. These results suggest that cultivars with a long duration of vegetative growth, high weight per tiller, and adequate tillers per square meter can produce high dry matter yield in both crops. There was a significant interaction (P < 0.05) in total dry matter yield between cultivar or line and cultivation type. The total dry matter yield of Taporuri in twice harvesting was about 10% higher than that in once harvesting, whereas that of Hinohikari was about 10% lower. The suitability for twice harvesting ([total dry matter yield in twice harvesting]/[total dry matter yield in once harvesting]) was significantly positively correlated (r = 0.875) with the increase in dry weight before the full heading stage, but significantly negatively correlated (r = −0.903) with the increase in dry weight between full heading and the yellow ripe stage. Thus, cultivars with a high increase in dry weight before full heading appear to be more suitable for twice harvesting than those with a high increase between full heading and the yellow ripe stage. In addition, our study showed that twice harvesting can prevent lodging in Taporuri, thereby increasing the suitability of this cultivar as a forage rice. Our results suggest that twice harvesting can be performed in southwestern Japan and warmer regions. 相似文献