Rice (O. sativa and O. glaberrima) is one of the world's most important crops, particularly in Asia, but increasingly so in Africa and Latin America as well. Insect. The _spikelets_ are rather small, narrow, greenish or purplish, 1/15 inch long or less, the rachilla is slender, produced to about half the length of the spikelet behind the palea. 225-578-4143 2011). Key words: Dry weight, Gibberellic acid, Number of spikelets, Rice, Spikelet degeneration, Spikelet differentiation. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional. 3.2. It consists of two glumes and one or more florets. web@agcenter.lsu.edu, 106 Martin D. Woodin Hall 225-578-4161 Lemma is a phytomorphological term referring to a part of the spikelet. Similarly, Africa’s i… Despite worldwide production increased due to improved varieties and agronomy, it is stagnating since about 10 years in many regions (Ray et al., 2013). If the infestation is severe it may cause yield loss up to 30%. In rice there is a single floret represented here by the lemma, palea and grain. (2008) observed that rice pollen germinated on the stigma within 2 min of pollination, and the tube reached 2017c ). The panicle size, an important agronomic trait that makes valuable contributions to the grain productivity in rice (Oryza sativa L.), mainly depends on the number of spikelets on a panicle [1,2,3,4].The final panicle size depends on the developmental processes of both spikelet differentiation and spikelet degeneration [].The phenomenon of young spikelet degeneration in cereal crops such … Introduction. Reduction or elimination of spikelet degeneration to increase spikelet number is critical in increasing the grain yield of cereals. The small structures labeled "glumes" are rudimentary structures sometimes called bracts instead of glumes. (2015) found a significant negative relationship between spikelet tissue temperature and spikelet … high tube growth rate characterize rice cultivars,which main-tain spikelet fertility and seed set in hot or cold temperature stress (Endo et al. Thus, heat-tolerant and heat-susceptible genotypes were used to investigate their differences in terms of phenotypic responses and expression changes of Hsf genes at the pre-flowering stage under heat stress. In rice there is a single floret represented here by the lemma, palea and grain. See more. 2008; Quampah et al. Yield Components of Rice 3.2.1. 2010;Rang et al. 1b). The molecular mechanisms underlying spikelet development and evolution are unclear. In this step the area labeled "embryo" is also removed. 2017), and the seeds shatter in the mature stage.Therefore, the upper 1st to 5th spikelets on the top primary branch in a panicle were collected in the flowering stage, and their awn lengths were measured (Fig. Rice is a staple food crop and the threshold temperature for its pollination is 35 °C. Both nymphs and adults suck the content out of grains from pre-flowering spikelets to soft dough stage. The endosperm is mostly carbohydrates. n. A small or secondary spike, characteristic of grasses and sedges, bearing one or more florets and usually subtended by one or two bracts. The mature rice kernel or grain is made up of several parts. (1875, p. 125) of the rice spikelet ilndicates six bracts, four of whIiel are called glumes. Both the urban and rural poor require food at affordable prices and this must come from increased productivity in intensive rice systems, which account for 75% of total rice production. The outer protective structures are called the hulls. The number of rice spikelets per square meter (S) is often positively correlated with the yield of rice (Evans, 1993) and is the most important component of grain yield (Yoshida, 1981). Global warming is rising as a serious concern affecting agricultural production worldwide. This leads to unfilled, empty and discolored grains. Shi et al. In wild rice, awn length varies according to the spikelet position in the panicle (Fig. Chen et al. Plants harvested at the high cutting height produced higher grain yield of the second crop because of the larger spikelet number m −2 and better grain filling using abundant leaf area index (LAI) and nonstructural carbohydrate (NSC) in the stubble. Notably, the spikelet of wild-type rice is determinate and produces only one fertile floret, but “two-florets spikelet” and “three-florets spikelet” mutants have been genetically selected (Ren et al. 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