Lemma Length Research Articles

Analysis on the growth pattern of glume in rice.

Grain size is one of the important yield components and it has influences on grain yield as well as grain quality. However, it has not been well understood how grain size is determined. Certainly, glume size is one of the important factors affecting grain size. We analyzed in detail the growth of glume (floral glume) of several rice varieties differing in sizes of their glumes. 1. The growth of glume in both length (lemma length) and width (floret width) were well fitted to a logistic curve (Fig. 1). This indicates that the growth pattern of glume can be characterized by parameters estimated from the logistic curve. In every variety, the growth of the glume in length ceased earlier than that in width (Figs. 2 and 3). Thus, the growth of glume in length did not synchronize with that in width. The intervarietal differences of growth period did not correspond with those of the glume length. However, the maximum growth rate of glume in length correlated highly with the final glume length, indicating that the differences in the final glume length was due to the differences in the maximum growth rate of glume length among the variesies (Table 1, Fig. 2). on the other hand, in the glume width, we could not detect any distinct intervarietal differences in growth period or maximum growth rate (Table 2, Fig. 3). It must be noticed that the relatively wide glume of "Arborio" was caused by the prolonged growth but not by the high growth rate (Table 2). 2. The growth patterns of glume in length and in width are different and the length and width of glume may be controlled by different regulatory systems. In this point, we need to analyze the growth pattern of glume and the mechanism of determination of its size in more detail. 3. Intersecting lines comprising three straight lines could be fitted to the allometric growth between the glume length and width (Fig. 4). In every variety, the coefficient of allometry was minimum in the second section and maximum in the last (Table 3). Intervarietal differences were detected in the coefficients of allometry and the positions of intersecting points. It is clarified that the shape of glume is affected by both the ratio of growth rate in length and to that in width of glume and the time lag of the growth period in the width relative to that in the length. 4. The present results show that the size and shape of rice glume are controlled by various parameters and we cannot assign any single factor determining the size or shape of glume during its growing process.

Notes on the taxonomy and nomenclature of Festuca occidentalis and F. idahoensis

Festuca occidentalis occurs in open forests and glades, always in at least partial shade. In British Columbia it occurs from the U.S.A. border to about latitude 57° N. It has leaf structure, panicle structure, spikelet length, glume length, lemma length, lemma scabrosity, awn length, anther length, and ovary vestiture which are different from F. idahoensis. Festuca idahoensis is found in grasslands (including subalpine meadows) and in openings in dry forests bordering grasslands, always in open, nonshaded situations. In British Columbia it occurs from the U.S.A. border northward to about 51° N. Despite the recent lumping of these two taxa, morphological and ecological evidence strongly suggests that they should be treated as separate species.

Evolution of reproductive behaviour in the genus eleusine

The paper traces shifts in the reproductive behaviour as influenced by the selective pressures of crop domestication, in the genus Eleusine, from the wild species. E. africana to its domesticated form E. coracana. Among other changes we consider temporal features of flowering, nature of anthesis and dehiscence, the stigma to lemma length ratio determining the extent of stigma protrusion and the pollen grain to ovule ratio as important in changing the breeding behaviours. These changes are viewed as evolutionary responses of plants to their respective ecological niches.

Development of the Rice Panicle : I. Characteristics of the growth of spikelets at different positions on panicle

This study was undertaken to elucidate the growth process of young panicle of rice. The growth of each spikelet was investigated in relation to the positional differences and was compared with that treated with thinning and top-dressing at the end of spikelet differentiation stage (16 days before heading). Three spikelet positions, the upper (T-1), the middle (M-2) and the lower (B-2'), were selected for this experiment (Fig. 1a, b). The results obtained are summarized as follows: 1. In controls, the length of lemma, empty glumes and the width of spikelet at maturation decreased on lower position. But there was little differences in the length of anther and pistil, and the diameter of pollen among the spikelets at different positions on panicle (Fig. 2, Table 3 and 4). 2. The growth of each spikelet proceeded succesively from the upper to the lower position on panicle (Fig. 3). 3. Interrelationships of the growth of each spikelet organ were almost the same in all spikelets on panicle. Lemma, anther and pistil in a spikelet began to grow simultaneously. Marked growth occurred in lemma from 16 to 8 days before flowering, in anther and pistil from 16 to 3 or 2 days before flowering, and in the width of spikelet from 16 to 6 days before flowering (Fig. 4). 4. Regardless of spikelet position on panicle, meiosis of pollen was found to occur in the anther of the same length. However, the lemma length at meiotic stage in the upper spikelet was different from that in the lower one. Meiosis of the upper spikelet occurred when it was smaller than the lower spikelet (Fig. 2 a, c). 5. When the nutritive conditions were improved by thinning and top-dressing, the length of panicle, the number of spikelet, the length of primary branches and the diameter of rachis increased. The increase of the spikelet number was due to the decrease of degenerative spikelets (Table 1 and 2). 6. The lemma length of middle and lower spikelets, the length of empty glumes and pistil of all spikelcts, were increased by the treatment. The anther length and the pollen diameter in all spikelets were not increased and the growth period of anther in the lower spikelet was shortened by the treatment. The growth of the upper spikelet was not promoted by the treatment (Fig. 5, Table 3 and 4). Thus, the spikelet organs, which seemed to be differentiated in various manner from the apex, showed the different responses to the treatment. From these results, it is assumed that the positional differences in the spikelet growth were not only dependent upon the distribution of translocated substances but also upon the physiological specificity of each organ of the spikelet.