Variation in leaf area development and its effect on water use, yield and harvest index of droughted wheat

1987 ◽  
Vol 38 (6) ◽  
pp. 983 ◽  
Author(s):  
RA Richards ◽  
TF Townley-Smith

Genotypes, chosen because of their variation in flowering, tillering and early leaf growth, were evaluated in 1 m long tubes in a glasshouse. These traits were selected for two reasons: firstly, because it was presumed they influence leaf area development and hence the water use, harvest index and yield of droughted wheat; secondly, because they are amenable to genetic manipulation and therefore can be selected in a breeding program. Four drought treatments were imposed in each of two seasons. The treatments and cultural conditions simulated droughts encountered by field-grown crops. Grain yield varied according to the amount of growth and water use before and after anthesis in relation to soil water supply. In the wettest treatments where plants had adequate water up to anthesis but were droughted thereafter (akin to a wet mediterranean-type environment), grain yield was positively associated with the amount of preanthesis growth. In the drier treatments, where droughts were sustained from before anthesis, genotypes having traits that reduced leaf area index saved more water for use after anthesis and had a higher harvest index and grain yield. However, pre-anthesis growth was also important, as it was estimated that in the driest treatments up to 60% of the grain dry weight was formed from reserves present at anthesis. These reserves represented up to 15% of the above-ground biomass at anthesis. Harvest index (y) was a nonlinear function of the proportion of water used after anthesis (x), y = 0.10 + 0.13 ln(x), r2 = 0.82 (P < 0.01).The determinate tillering or 'uniculm' wheats, although having some advantages over conventional tillering lines when sown at the same density, were largely indistinguishable from conventional wheats in their water use pattern when sown at twice the density. However, at both densities they had a higher stem weight per unit length and a higher specific leaf weight than conventional wheats, and this resulted in them having a lower harvest index and grain yield. These pleiotropic effects may reduce the possible advantages of these wheats, that is a reduced maximum leaf area and no sterile tillers, in dry environments.

1973 ◽  
Vol 81 (3) ◽  
pp. 449-453 ◽  
Author(s):  
B. A. C. Enyi

SUMMARYIn each of the crops studied, weeding increased grain yield, weeding 2 weeks after sowing being better than weeding either four or eight weeks after sowing and weeding two and four weeks after sowing being better than weeding either two and eight weeks or four and eight weeks aftersowing. Weeding thrice (two, four and eight weeks after sowing) was significantly superior to all the other weeding treatments. Weeding increased leaf area index, dry weight of side and mainstem and number of mature pods at harvest in green gram and cowpeas. In sorghum, apart from increasing leaf area index, it also increased the length of ears and grain weight per unit lengthof ear. The weeding treatments affected grain yield in cowpeas and green gram due totheir influence on leaf area development, development of the main and side stems and on the number of mature pods produced at harvest. The effect of the weeding treatments on grain yield of sorghum was due to their influence on leaf area development, length of ear and grain weight perunit length of ear.


Agriculture ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 365
Author(s):  
Milan Brankov ◽  
Milena Simić ◽  
Željko Dolijanović ◽  
Miloš Rajković ◽  
Violeta Mandić ◽  
...  

The objective of this study was to evaluate the impact of two foliar fertilizers applied on five maize (Zea mays L.) lines. Fertilizers were applied at different growth stages of maize, during three consecutive years (2010–2012) at the experimental field of the Maize Research Institute “Zemun Polje”, Serbia. Maize growth parameters such as fresh matter, height, leaf area and grain yield were recorded. Foliar fertilizer with amino acids (FAA) was more advantageous to maize plants compared to fertilizer containing phosphorus (FP) as a main component. Applied FAA has shown positive effects by increasing fresh matter, leaf area index, and plant height in all three years. In 2012, due to unfavorable meteorological conditions, grain yield and harvest index were very low, compared to the previous two years, although, positive effects on morphological traits were observed 21 days after treatments (DAT), as well as in the anthesis stage. The best results of 30% of grain yield and harvest index increase were recorded in line L1 in 2010 and 2011. The same line had an increase of more than 40% of fresh matter and leaf area on average for all three years. The positive effects that have been noticed in this research could recommend foliar fertilizing with fertilizer containing N in a form of an amino acids complex.


1970 ◽  
Vol 48 (10) ◽  
pp. 1801-1804 ◽  
Author(s):  
D. F. W. Pollard

Different shoot types in aspen crowns carried leaves of different ages; leaders continued to produce leaves until early August and always carried some young leaves, whereas short shoots completed development by mid-June. Development of foliage on long shoots was intermediate between that on leaders and short shoots. Leaf area index of the 6-year-old stand reached a maximum of 2.4, of which 2.1 was contributed by short-shoot foliage. The rest was formed by leaders and long shoots. Young leaves on leaders and long shoots were not sufficient to influence total production in the stand appreciably, even though young aspen leaves may have high photosynthetic efficiencies. These young leaves could, however, influence height growth and lateral development of the canopy.


1974 ◽  
Vol 10 (2) ◽  
pp. 87-95 ◽  
Author(s):  
B. A. C. Enyi

SUMMARYApplication of dimecron to cowpea plants increased grain yield, its effect being more pronounced in widely spaced plants and those planted in March. Dimecron increased grain yield by encouraging greater leaf area development, by increasing the number of flowering inflorescences and the number of pods set per inflorescence, and by decreasing the number of shrivelled pods. March planting encouraged greater dry matter production than January and May planting. Dimecron application decreased the number of Ootheca beningseni, reduced the proportion of leaf damaged by these insects, and reduced the number of plants infested with aphids and Acidodis larvae.


1995 ◽  
Vol 46 (1) ◽  
pp. 99 ◽  
Author(s):  
F Giunta ◽  
R Motzo ◽  
M Deidda

A field experiment was carried out in Sardinia (Italy) on durum wheat to analyse the effects of different moisture treatments, irrigated (I), rainfed (R) and stressed (S), on leaf area index (LAI), radiation intercepted (Q) and water use (WU), efficiency of conversion of radiation and water into dry matter (RUE and WUE), nitrogen uptake and carbon and nitrogen partitioning in the above-ground part of the plant. In the period between beginning of stem elongation and heading, drought affected the maximum LA1 in the most stressed treatment (4.7 in S v. about 6.9 in R and I), but not Q and WU. RUE was also lowered by drought in this period (0.68 in S v. about 0.95 g MJ-1 in R and I) as a reduced biomass was recorded in S at heading (528gm-2 in S v. 777 g m-2 on average in R and I). In contrast with the previous period, the reduction in LA1 between heading and maximum ear weight (MEW) determined a significant reduction in Q and WU, WUE and RUE, resulting, ultimately, in notable differences in the total biomass produced until MEW (1203, 930 and 546 gm-2 in I, R and S respectively). The amount of stem reserves relocated to the grain decreased as the level of stress increased, going from 223gm-2 in I to 9gm-2 in S and was accumulated almost entirely (from 76% of the total in I to 100% in S), in the post-heading period. Nitrogen percentage was not affected by the treatments applied apart from the higher values in stem and flag leaf in S later in the growing season due to an inhibition of nitrogen translocation in S. The total nitrogen uptake was lower in S (12.3gm-2) than in I (16.6gm-2) only as a consequence of the different dry matter accumulation patterns. The importance of WUE in this type of Mediterranean environment is discussed, with particular concern to the key role of modulation of leaf area development through the growing season.


Helia ◽  
2015 ◽  
Vol 38 (62) ◽  
pp. 109-120 ◽  
Author(s):  
Vikrant Tyagi ◽  
S. K. Dhillon

AbstractNine new cms analogues on the base of diversified cms sources were developed and evaluated for morphological, agronomic, physiological and biochemical traits, including the field resistance to the prevalent diseases of sunflower under Punjab conditions. As a result of this study, the most prospective cms analogues were designated for future use in hybrid breeding programme. The results revealed that selection for tall plants with large head size and high chlorophyll content may be associated with high grain yield as well as oil content and high oleic acid content in sunflower. Leaf dry weight, biological yield, harvest index, specific leaf weight and relative leaf water content had direct positive effect on grain yield. The harvest index, specific leaf weight/plant, leaf area index and leaf area had indirect effects (through leaf dry weight) on grain yield. These traits are advocated as selection criteria for grain yield improvement in sunflower.


1975 ◽  
Vol 26 (1) ◽  
pp. 31 ◽  
Author(s):  
KS Fischer ◽  
GL Wilson

Growth analysis was applied to grain sorghum (cv. RS610) grown at low, medium and high population densities, i.e. 14,352, 143,520 and 645,836 plants ha-1 respectively. The medium densities had two arrangements of plants, square (S) and rectangular (R). Crop growth rates, inflorescence growth rates, leaf area indices, net assimilation rates and leaf growth rates were calculated from growth functions of plant dry matter and leaf area over time. Differences in crop growth rate between populations in the early stages were attributed to leaf area development—specifically to the initial leaf area (dependent on seedling number) and not to differences in leaf growth rates. Peak crop growth rates were 15.0, 27.5, 26.0 and 45.8 g m-2 day-1 for the low, medium (S), medium (R) and high populations respectively.The large difference between the growth rates of the medium (S) and the high populations was not explained by differences in the amount of radiation intercepted. Although leaf area indices were 4.6 and 10.2 respectively for the two populations, both canopies intercepted almost all of the noon radiation. Light extinction coefficients were 0.45 and 0.29 respectively. The relationship between net assimilation rate and leaf area index was such that for comparable leaf area indices above 2, plants at higher densities showed greater improvement in yield per unit increment in leaf area index. A maximum grain yield of 14,250 kg ha-1 was obtained at the high population density as a result of higher dry matter production, but a similar harvest index to that of the crops grown at the other densities. Inflorescence growth rate (g m-2 day-l) slightly exceeded crop growth rate in the latter part of grain filling, which indicated that there was some retranslocation to the grain of previously assimilated material. The maximum grain yield represents an efficiency of utilization of short-wave solar radiation during crop life of 2.5 x 10-6g cal-1. *Part IV, Aust. J. Agric. Res., 26: 25 (1975).


2013 ◽  
Vol 404 ◽  
pp. 415-419
Author(s):  
Heng Jia Zhang ◽  
Jun Hui Li

The soil water contents in spring maize field were monitored continuously using soil neutron probe combined with drying-weighing method. Meanwhile, the effect of limited irrigation on crop periodic water consumption and its percentage in total water use, leaf area index, and grain yield of spring maize were explored. The results indicated that both the periodic water consumption and its percentage in total water use varied from low to high then to low within maize growing season, with the maximum valued both at silking to middle grain filling. In addition, leaf area indexes were greatly improved by full irrigation before maize filling, and grain yield was not reduced by efficient limited irrigation management, contrarily, yield increase and 31.1% of significant irrigation water saving were achieved, which was beneficial to the optimization of soil water ecological processing and limited irrigation management.


2011 ◽  
Vol 62 (12) ◽  
pp. 1045 ◽  
Author(s):  
A. M. Massignam ◽  
S. C. Chapman ◽  
G. L. Hammer ◽  
S. Fukai

Nitrogen (N) limitation reduces canopy carbon assimilation by directly reducing leaf photosynthesis, and by developmentally reducing the rate of new leaf area development and accelerating leaf senescence. Effective use of N for biomass production under N limitation may be considered to be a result of a trade-off between the use of N to maintain high levels of specific leaf nitrogen (SLN the amount of N per unit leaf area) for high photosynthetic rate versus using N to maintain leaf area development (leaf area index – LAI). The objective here is to compare the effects of N supply on the dynamics of LAI and SLN for two crops, maize (Zea mays L.) and sunflower (Helianthus annuus L.) that contrast in the structure and development of their canopy. Three irrigated experiments imposed different levels of N and plant density. While LAI in both maize and sunflower was reduced under N limitation, leaf area development was more responsive to N supply in sunflower than maize. Observations near anthesis showed that sunflower tended to maintain SLN and adjust leaf area under reduced N supply, whereas maize tended to maintain leaf area and adjust SLN first, and, when this was not sufficient, SLN was also reduced. The two species responded differently to variation in N supply, and the implication of these different strategies for crop adaptation and management is discussed.


1995 ◽  
Vol 46 (5) ◽  
pp. 845
Author(s):  
SP Milroy ◽  
PJ Goyne

A model to simulate leaf area development for barley at the whole plant level was constructed. Data for leaf area development in the absence of soil water stress were collected from irrigated field trials grown at Hermitage Research Station, near Warwick, Queensland, in 1990. The response of leaf area expansion to soil water status was measured in a glasshouse trial. In the model, green leaf area per plant (GPLA) is derived as the difference between total leaf area produced per plant (TPLA) and senesced leaf area (SPLA). TPLA and SPLA are described by logistic functions of thermal time. Two types of senescence are included: that due to ageing of the whole plant (ontogenetic senescence) and senescence associated with the development of large canopies (light-induced senescence). The onset of ontogenetic senescence is linked to anthesis, whereas light-induced senescence occurs if the leaf area index of the crop exceeds 5.5. Leaf expansion of plants in pots varying in the fraction of transpirable soil water available (FTSW) was compared with leaf expansion of those in well-watered pots three times per week. The relationship between relative leaf expansion (RLE) and FTSW was described by a logistic function (r2 = 0.96). A 50% reduction in RLE occurred when FTSW = 0.34. Similarly, a logistic function described the relationship between relative transpiration (RT) and FTSW (r2 = 0.96). A 50% reduction in RT occurred when FTSW = 0.17. Potential leaf expansion as predicted by the non-stressed model was reduced in response to moisture stress via a ramp function relating RLE to RT. The model gave an unbiased prediction of the leaf area dynamics for 21 rainfed and irrigated crops of barley grown in southern Queensland between 1986 and 1993 (RMSD = 1.09 m2 m-2, r2 = 0.75, n = 76). Precision may have been reduced by the lack of information available on parameters for soil water balance when barley is grown on a range of soil types.


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