MAIZE (ZEA MAYS) LEAF ANGLE AND EMERGENCE AS AFFECTED BY SEED ORIENTATION AT PLANTING

Abstract

Maize (Zea mays ) seed orientation at planting can influence emerging leaf angle. If leaf angle were consistent among plants without leaf overlap, large numbers of these bilaterally symmetrical plants could be arranged to optimize light interception and possibly increase grain yields or maintain grain yield with a lower population. The objectives were to evaluate the effect of seed orientation in soil on the angle of maize leaves relative to the planted row and on emergence rate. Seeds were planted 2.5 cm deep in diverse combinations of flat, cotyledon down, cotyledon up, on their side, radicle up and radicle down. Each seed orientation was repeated 10 times. Data on days to emergence and leaf angle were collected. In three experiments, maize seeds planted flat with the cotyledon up resulted in homogenous and faster emergence, and maize leaves aligned perpendicular to the direction of the maize row. Similar results were achieved with maize seeds planted parallel to the row with the radicle down. Random placement of maize seeds resulted in random orientation of maize leaves and lower emergence rates. The effects of controlled leaf geometry could facilitate planting higher populations with the potential for increasing grain yield and/or allow the maintenance of grain yields while reducing seed rates.

Scaling of FAPAR from the Field to the Satellite

“…This assumption was verified as feasible in developing FAPAR-P model. However, the leaf angle distribution of maize is also found to be variable with seed orientation [58] and phenological stages [59]. The use of more precise description of leaf angle distribution could thus be considered in other work.…”

Leaf orientation of maize plants as influenced by seed positioning in the soil

“…Strategic positioning of seeds in the planting furrow may allow the leaves to be oriented in the horizontal plane perpendicularly to the sowing row, which would reduce leaf overlap (shading) and thus increase PAR interception and grain yield (Fortin & Pierce, 1996;Toler, Murdock, Stapleton, & Wallace, 1999;Torres, Vossenkemper, Raun, & Taylor, 2011;Taiz, Moller, & Murphy, 2017;Sangoi, Ender, Guidolin, Almeida, & Heberle, 2001). Fortin and Pierce (1996) suggested that the random orientation of maize ear leaves is a result of random positioning of seeds in the furrow.…”

“…As stated by Toler et al (1999), this phenomenon occurs when the seed is placed vertically with the tip pointing down in the soil and the embryo facing the middle of the inter-row, which results in higher grain yields than when the seed is sown randomly. In addition to this position, Torres et al (2011) sowed flat seeds horizontally with the dorsal face down and found this position to be beneficial for leaf orientation, as it prevented shading.…”

“…Most studies investigating leaf orientation in the horizontal plane have been conducted with flat seeds and only a few with round seeds, most likely due to the ease of sowing the former type. The morphology of the maize plant, whose leaves are inserted at the stem in an opposite, distally and bilaterally symmetrical manner (Castro, Kluge, & Sestari, 2008), also contributes to the arrangement of plants parallel to each other and their leaves being positioned perpendicularly to the sowing row (Loomis & Williams, 1969;Girardin, 1992;Fortin, & Pierce, 1996;Toler et al, 1999;Torres et al, 2011). This is probably a result of the combination of the oriented position of the seed in the planting furrow coupled with the natural position of the embryonic axis (radicle, hypocotyl and the plumule) within the seed.…”

“…When seeds are stimulated by environmental factors (gravitropism), the plumule grows toward the light and the radicle toward the lower soil layers in search for water and nutrients (Taiz et al, 2017). Together, those resources would be the main factors to enable an ordered maintenance of symmetrical bilateral growth in maize plants oriented perpendicularly to the sowing row (Loomis & Williams 1969;Girardin, 1992;Fortin & Pierce, 1996;Toler et al, 1999;Torres et al, 2011).…”