SOURCE-SINK LIMITATIONS OF MAIZE GROWING IN AN OUTDOOR HYDROPONIC SYSTEM

1988 ◽  
Vol 68 (4) ◽  
pp. 947-955 ◽  
Author(s):  
G. K. WALKER ◽  
M. H. MILLER ◽  
M. TOLLENAAR

Experiments were conducted from 1983 to 1985 to test the hypothesis that rate of dry matter accumulation by maize (Zea mays L.) during grain filling can be enhanced by an increase in assimilate demand for grain filling (i.e., sink strength).The sink strength of maize plants grown in an outdoor hydroponic system was varied independently of the source strength by manipulating the plant spacing during the period in which final kernel number is established. The crop growth rate during grain filling, the dry matter of leaves, stems, ears and roots, and grain yield components were determined. In all 3 yr the crop growth rate during grain filling of plants that had been growing at a 20 000 plants ha−1 spacing for variable periods and were returned to the control density of 80 000 plants ha−1 at the start of the grain-filling period was lower than that of plants grown continuously at a spacing of 80 000 plants ha−1. In 1985, plants grown at 20 000 plants ha−1 from 3 wk preanthesis until 2 wk postanthesis and at 80 000 plants ha−1 thereafter had 50% more kernels per plant than the control plants. However, the net photosynthesis during grain filling was not increased; in fact it was somewhat lower. Final grain yield was not significantly different, mainly due to greater translocation from the stems to the grain in the spaced plants than in the controls. These studies indicate that maize growing in a nonlimiting below-ground environment is not sink limited. Hence adding sink capacity by maintaining kernel number while increasing plant density or by adding more kernels per plant would not appear to be a promising route for raising the yield potential.Key words: Sink strength, hydroponics, plant spacing, kernel number, yield components

2017 ◽  
Vol 14 (2) ◽  
pp. 147-154 ◽  
Author(s):  
MM Kamrozzaman ◽  
MAH Khan ◽  
S Ahmed ◽  
N Sultana

An experiment was conducted at Sadipur charland under Farming System Research and Development Site, Hatgobindapur, Faridpur, during rabi season of 2012-13 and 2013-14 to study the growth and yield performance of cv. BARI Gom-24 as affected by different dates of sowing under Agro-ecological Zone-12 (AEZ-12) of Bangladesh. The experiment was laid out in randomized complete block design with six replications, comprising five different dates of sowing viz. November 5, November 15, November 25, December 5 and December 15. Results reveal that the tallest plant, leaf area index, total dry matter, and crop growth rate were observed in November 25 sown crop and leaf area index, total dry matter and crop growth rate were higher at booting, grain filling, and tillering stages of the crop. Maximum effective tillers hill-1 (3.49), spikes m-2, (311), number of grains spike-1 (42.20) and 1000-grain weight (52.10 g) were produced by November 25 sown crop exhibited the highest grain (4.30 t ha-1) and straw yield (4.94 t ha-1) as well as harvest index (46.88%) of the crop. Lowest performance was observed both in early (November 5) and late sown crop (December 15). The overall results indicated that November 25 sown crop showed better performance in respect of growth and yield of wheat under charland ecosystem of Bangladesh.J. Bangladesh Agril. Univ. 14(2): 147-154, December 2016


Author(s):  
D. Dev Kumar ◽  
D. Vishnu Vardhan Reddy ◽  
P. Raghuveer Rao ◽  
M. Sheshu Madhav ◽  
V. Gouri Shankar

The experimental field was laid in RBD replicated thrice with 30 high yielding rice genotypes which includes 26 advanced breeding lines (ABL) (SP-351, SP-352, SP-353, SP-354, SP-355, SP-356, SP-357, SP-358, SP-359, SP-360, SP-70, SP-72, SP-63, SP-61, SP-69, SP-55, SP-80, SP-25, SP-13,  SP-03, SP-02, SP-34, SP-37, SP-08, SP-75 and SP-57) and four checks (NDR-359, BPT-5204, IR-64, Jaya). Seven genotypes showed significantly higher leaf weight over the BPT-5204. Further, leaf weight at panicle initiation stage showed a positive relationship with TDM (Total Dry Matter) (r=0.51**). At the panicle initiation stage, only three genotypes (SP-354, SP-358, and SP-72) were superior to BPT-5204 in leaf weight. The shoot biomass and total dry weight was superior only in one genotype SP-72 as compared to BPT-5204. Similarly, the net assimilation rate at panicle initiation stage was maximum in SP-08 (9.92g m-2 day-1) and SP-72 (9.35g m-2 day-1) as compared to check BPT-5204 (6.47g m-2 day-1). These genotypes maintained higher photosynthetic rate (SP-72) and higher grain yield (SP-08). The relationship between CGR (Crop Growth Rate) and TDM (Total Dry Matter) and grain yield (r=0.61**) was positive and significant at physiological maturity. Genotypes SP-08 and SP-72 showed significantly higher CGR (Crop Growth Rate) over BPT-5204 and hence, yielded higher. In the present study compared to BPT-5204, genotypes SP-72, SP-08 maintained higher lea area index at all crop growth stages. These genotypes maintained higher photosynthetic rate (SP-72) and higher grain yield (SP-08). Positive significant relationship between LAI (Leaf Area Index) and total dry matter at harvest and; grain yield has been observed.


1982 ◽  
Vol 62 (4) ◽  
pp. 855-860 ◽  
Author(s):  
M. TOLLENAAR ◽  
T. B. DAYNARD

The effect of source-sink ratio (i.e., the ability of the leaves to produce photosynthate versus the capacity of the grain to accommodate the assimilates) on dry matter accumulation and leaf senescence during the grain filling period of two short-season maize (Zea mays L.) hybrids was investigated in 1979 and 1980. Source-sink ratio of the maize hybrids was altered by ear removal at midsilking and at 3 wk after midsilking; by partial fertilization of the topmost ear so that treatment ears contained approximately 50% of kernel number of the control; and by removal of all leaf blades but that of the ear leaf at 2 wk after midsilking. Crop growth rate during the period from 3–5 wk after midsilking was reduced by 30% for the partly fertilized treatment and by 60% for both ear removal treatments. During the period from 5 to 7 wk after midsilking, the treatment-by-hybrid interaction for crop growth rate reflected different patterns of leaf senescence. In one hybrid, treatments which caused reductions in sink size delayed leaf senescence and increased the crop growth during the 5 to 7-wk postsilking interval, relative to the control. The reverse was evident for the other hybrid. Partial defoliation tended to cause the remaining ear leaf to senescence slightly earlier than in the control. Apparently two types of leaf senescence occurred: senescence due to assimilate starvation, and senescence due to excessive assimilate accumulation. The former caused by excessively low source-sink ratio and the latter caused by excessively high source-sink ratio. These results indicate that a delicate balance exists between sink and source during the grain-filling period of maize, and that disturbance of this balance can cause substantial yield reductions, plus an acceleration of leaf senescence and maturation processes.


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 64 (6) ◽  
pp. 580 ◽  
Author(s):  
A. Cerrudo ◽  
J. Di Matteo ◽  
E. Fernandez ◽  
M. Robles ◽  
L. Olmedo Pico ◽  
...  

Maize (Zea mays) grain yield has been described to be particularly susceptible to environmental conditions around silking; however, a better temporal description of the effect of resource deprivation during this period is needed. Additionally, yield progress and the subsequent increase in the demand of assimilates may result in source limitation during the grain-filling period in current hybrids. This work assessed the effect of (i) short (~5 days) and intense shading stresses imposed at different times, and (ii) thinning during the effective grain-filling period, on yield components of an Argentinean, widespread hybrid. Grain yield was affected by resource availability during an extended period from ~300 growing degree-days (GDD) before silking to ~780 GDD after silking (base temperature = 8°C). Kernel number (KN) was reduced by shading treatments imposed within a relatively extended period of ~700 GDD centred on silking. Within this period, we establish a critical period of ~30 days around silking (i.e. –200 to 250 GDD after silking), in which KN susceptibility was maximal. The variation in KN during this period of 450 GDD was mainly accounted for by resource availability and not by timing of treatment imposition within this window. A direct relationship between KN and weight per kernel (KW) for shading treatments imposed from 0 to 200 GDD after silking indicated that compensation of KN reduction by KW increase might not be expected when stress occurred immediately after silking. Kernel number and KW presented an inverse relationship when shading took place after 200 GDD after silking. In addition, thinning after the onset of the effective grain-filling period increased KW. The results indicate that, even in the undisturbed crop, KW was limited by source capacity during grain filling. It is suggested that there is a need to reconsider current agronomic practices and breeding strategies, focusing on the source capacity during the grain-filling period.


2003 ◽  
Vol 83 (5) ◽  
pp. 483-495 ◽  
Author(s):  
B. L. Ma ◽  
J. Ying ◽  
L. M. Dwyer ◽  
E. G. Gregorich ◽  
M. J. Morrison

Relying less on fertilizer N and more on crop residual and biological N2 fixation by legume crops has been suggested as an effective way to meet the challenge of maximizing economic return while minimizing environmental pollution. A field study was conducted on a Brandon loam soil (Orthic Humic Gleysol) to determine the effects of crop rotation and N amendments on grain yield, crop growth, N uptake and use efficiency (NUE) of maize ( Zea mays L.) and fertilizer replacement values of legume. The rotations included maize in annual rotation with soybean [Glycine max (L.) Merrill], alfalfa ( Medicago sativa L.) or continuous maize. The soil N amendments included no amendment, NH4NO3 at 100 kg N ha-1, stockpiled or rotted dairy manure at 50 Mg ha-1 (wet weight). Averaged across 4 yr, increases in maize grain yield, total plant N uptake, and NUE ranged from 13 to 35% in the maize-soybean and maize-alfalfa rotations compared to continuous maize monoculture. During the study, total dry matter production was 15 to 35% higher and crop growth rate was 13 to 23% higher for maize following alfalfa than for continuous maize monoculture. The effect of legumes on the subsequent growth of maize (i.e., total dry matter production a n d crop growth rate) was most apparent during the grain filling period. Total maize dry matter production was similar up to silking stage for all three rotation systems; however, the difference in total dry matter between maize monoculture and maize in rotation with legume continued to increase after this stage so that the greatest differences were observed at physiological maturity. Grain yield was 19% higher in the 100 kg N ha-1 treatment and 23% higher in the repeated manure amendment than in the unfertilized treatment. Fertilizer N replacement values were on average, 68 kg ha-1 for soybean and 133 kg ha-1 for alfalfa. Our results indicate that maize in annual rotation with legume crops could increase the maize yields by as much as 20% and reduce the amount of chemical fertilizer N by as much as 180 kg N ha-1. The effect of legume preceding crop on maize dry matter production and N uptake is expressed mostly in the later stages of crop growth in this mid- to short-growing- season region. Key words: Rotation, Zea mays, dry matter accumulation, crop growth rate, manure, nitrogen use efficiency


1991 ◽  
Vol 116 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. Savin ◽  
G. A. Slafer

SUMMARYShading treatments of 50% of the incident radiation were applied to the semidwarf wheat cultivar Leones INTA before and after anthesis in two field experiments in Argentina in 1987 and 1988. The treatments reduced biological (above-ground dry matter) yield, grain yield and number of grains/m2. Number of grains/m2 was closely and linearly correlated with ear dry weight at anthesis and with the photothermal quotient, calculated from 20 days before to 10 days after anthesis. Grain yield was sink limited, and the shading treatments reduced sink strength. The contribution of preanthesis assimilates to grain yield was smaller in the shaded crops than in the unshaded controls; in unshaded crops, almost 40% of grain yield was contributed by preanthesis assimilates whilst in preanthesis shaded crops this contribution was negligible. The proportion of preanthesis assimilates contributed to the grain was closely related to the decrease in stem dry weight during grain filling. The effects of shading on main stems and tillers were the same.


1970 ◽  
Vol 40 (2) ◽  
pp. 133-138 ◽  
Author(s):  
MMA Mondal ◽  
MSA Fakir ◽  
M Nurul Islam ◽  
MA Samad

Growth rate of mungbean was very slow during the vegetative phase in all the four genotypes. A relatively smaller portion of total dry matter (TDM) was produced before flower initiation and the bulk of it after anthesis. The maximum crop growth rate (CGR) was observed due to maximum leaf area (LA) development during the pod filling stage in all the genotypes. LA and CGR contributed to the superior TDM production. It appeared that a high yielding mungbean genotype should possess larger LA, high TDM production ability, superior CGR at all the growth stages, high relative growth rate and net assimilation rate at the vegetative stage as superior yield components. Key words: Seed yield; Mungbean; Growth; Dry matter DOI: http://dx.doi.org/10.3329/bjb.v40i2.9768   Bangladesh J. Bot. 40(2): 133-138, 2011 (December)  


1994 ◽  
Vol 122 (2) ◽  
pp. 241-247 ◽  
Author(s):  
Prabhjeet Singh ◽  
S. C. Bhargava

SUMMARYInoculation ofBrassica napuscv. ISN–129 withAzotobacter chroococcumfollowing the application of different amounts of nitrogen produced the greatest increase in seed yield and total dry matter when no external nitrogen had been applied. The yield increase in response to inoculation could be attributed to a greater number of primary branches and pods, associated with a higher leaf area index, particularly at the pod-filling stage, and a faster crop growth rate.


1977 ◽  
Vol 4 (5) ◽  
pp. 785 ◽  
Author(s):  
I Sofield ◽  
LT Evans ◽  
MG Cook ◽  
IF Wardlaw

Controlled-environment conditions were used to examine the effects of cultivar and of temperature and illuminance after anthesis on grain setting and on the duration and rate of grain growth. After an initial lag period, which did not differ greatly between cultivars, grain dry weight increased linearly under most conditions until final grain weight was approached. Growth rate per grain depended on floret position within the ear, varied between cultivars (those with larger grains at maturity having a faster rate), and increased with rise in temperature. With cultivars in which grain number per ear was markedly affected by illuminance, light had relatively little effect on growth rate per grain. With those in which grain number was less affected by illuminance, growth rate per grain was highly responsive to it, especially in the more distal florets. In both cases there was a close relation between leaf photosynthetic rate as influenced by illuminance, the rate of grain growth per ear, and final grain yield per ear. The duration of linear grain growth, on the other hand, was scarcely influenced by illuminance, but was greatly reduced as temperature rose, with pronounced effects on grain yield per ear. Cultivars differed to some extent in their duration of linear growth, but these differences accounted for less of the difference in final weight per grain than did those in rate of grain growth. Under most conditions the cessation of grain growth did not appear to be due to lack of assimilates.


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