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2 INTRODUCTION Concept of physiological maturity PM is defined as occuring when the seed reaches its maximum dry weight, represent maximum viability and vigor. At PM nutrients are no longer flowing into the seed from the mother plant due to the breakdown of vascular bundle connecting seed to mother plant. PM permits an accurate measure of the duration of the grain filling period. PM also permits the estimation of harvest time which usually is within two weeks after PM.

3 INTRODUCTION Figure 1. Seed and its relation to mother plant Concept of physiological maturity Im-mature seed mature seed Aphid/soybean%20stages.

4 INTRODUCTION Concept of physiological maturity Seed Vigor Seed Dry Weight Seed Diameter Seed Moisture PM Perdomo (1985) Figure 2. PM of Beans

5 INTRODUCTION Sorghum Wheat Mungbean PPT in seed development and maturation, mungbean Figure 3. Maturity marker

6 Physiological maturity-Maize Introduction and Objective Formation of black layer in the placental region of corn as they matures were referred on the study of susceptibility of corn to kernel rots. Kiesselbach and Walker also suggested that the formation of black layer might serve as a reliable indicator of PM in corn. The study was conducted to explore such possibilities of formation of black layer as simple, practical, visual characteristic of maize seed as an accurate indicator of PM. Formation of black layer

7 Physiological maturity-Maize Formation of black layer Four hybrid varieties of different maturity levels were evaluated. Six plants per hybrids were selected for daily sampling of kernels. The sampling started at the approach of maturity as indicated by hardening of upper part of kernels and continued several days after the seed had reached its maximum dry weight. Each day 10 kernels were removed from a single kernel row in the middle of each ear and frozen.

8 Physiological maturity-Maize Formation of black layer Two kernels per sample were cut lengthwise and development of black layer was examined and recorded. Figure 4. length wise view for development of black layer

9 Physiological maturity-Maize Formation of black layer Figure 5. Basal view of black layer with pedicel removed

10 Physiological maturity-Maize Formation of black layer Figure 6. Relationship between black layer formation and maximum kernel dry weights HybridsMaximum kernel dry weights (gm) Appearance of black layer (%) Sx XL SX A close linear correlation was found among hybrids between black layer and maximum kernel dry weights.

11 Physiological maturity-Maize Milk line as indicator of PM Introduction and Objective Many methods (grain moisture content, black layer formation, calendar days accumulation after silking) had been used in predicting PM in maize. Kernel moisture cannot be visibly determined and requires time to dry the grain. Black layer formation takes place very fast within 3 days and causes inability to tell when it is formed, there is also variability in appearance consisting huge kernel moisture ranging from 15.4 to 75%. Thus, the study on milk line as indicator of PM was done to find out more reliable and visual indicator which can be monitored over a period of time.

12 Physiological maturity-Maize Milk line as indicator of PM Five hybrids were evaluated. Samples (10 consecutive ears from middle row were collected in soft dough stage, dented stage, half milk line stage, and every four days there after. Ears were broken in the middle and position of milk lines were noted. Fresh weight, dry weight and moisture content were also determined.

13 Physiological maturity-Maize Milk line as indicator of PM Figure 7. Ears broken in the middle for milk line determination Figure 8. A milk line appears across the kernel opposite the embryo side. This line advances down toward the cop with maturity and dry down.

14 Physiological maturity-Maize Milk line as indicator of PM Figure 9. The position of milk line with different maturity level The milk line disappears( the corn becomes more solid) as the grain matures. No milk line wPage&librarypageid=131

15 Physiological maturity-Maize Milk line as indicator of PM Figure 10. Accumulation of kernel dry weight. S- soft dough, D- dented, H- half milk,P1- PM according to least square regression analysis, P2- Duncas Multiple Range test P3- PM by Polynomial regression analysis, NM- No milk line stage BL- Black layer completely formed.

16 Physiological maturity-Maize Result Black layer developed in all varieties. The relationship between maximum kernel dry weight and black layer formation was linear. Soft dough stage signaled the beginning of milk to solid conversation. Soon after fully dented stage, the milk line became externally visible on the kernel face opposite the germ and its progression could be monitored. Kernel moisture at the half milk line stage was 40%. Loss of all milk from kernel occurred an average of 2 days prior to black layer formation. Disappearance of milk line coincided with maximum kernel dry weight.

17 Physiological maturity-Maize Discussion There is a contrast report on formation of black layer with regard to moisture content (45% MC in cool autumn temperatures, 15.4% and 16.8% MC in two of in-breds and even 75% MC in one report). However in the present study under normal conditions both occurred simultaneously. But under stress condition black layer formation occurred while endosperm milk was still present. Black layer formation can be more reliable indicator of PM because of its consistence formation irrespective of environmental condition and grain moisture content because kernel dont accumulate dry mater after black layer formation.

18 Physiological maturity-Maize Discussion Milk line is more useful in monitoring grain maturation prior to PM because it can be easily visible and monitored during the maturation period. Half milk line stage can be used in pre-harvest planning purposes since it indicated that kernel contained 40% moisture and were 2 to 3 weeks from harvest.

19 Physiological maturity-Soybean Introduction and Objective Previous studies on soybean maturity was based on the loss of green color in the pod as indicator of PM. These studies were subjective and based on pods attached at specified nodes on the lower portion of the stem, thus the usefulness of their criteria for indicating PM of an entire soybean plant was not determined. The present study was therefore being done to determine if the loss of green color from pods was a reliable indicator of PM of an entire soybean plant or not. To relate disappearance of green pod color to the occurrence of other estimates already in use or describe in literature.

20 Physiological maturity-Soybean PM HM not mature Figure11. Soybean field at different maturity stage

21 Physiological maturity-Soybean Figure 12. Mature soybean plot PMHM

22 Physiological maturity-Soybean Figure 13. Sequence of pod formation and seed filling

23 Physiological maturity-Soybean Figure 14(a). The whole-plant dry weight (Solid lines) and seed moisture content (dashed lines) of soybean cultivars. Physiological maturity (PM) was determined as the intercept of a line representing mature seed weight and with a slope of the rate of seed weight increase. NoVisual characters 1Pod containg a green seed 2One normal pod on the main stem that has reached its mature color 3Pods free of green color 4Leaves free of green color 5Pods brown 6Petioles free of green color 7Stems free of green color 8Leaves fallen

24 Physiological maturity-Soybean NoVisual characters 2One normal pod on the main stem that has reached its mature color 3Pods free of green color (6) Figure 14(b).

25 Physiological maturity-Soybean Figure 15. Soybean P.M

26 Physiological maturity-Soybean Result Criteria no 3 ( pods free of green color) coincided with calculated PM most consistently. Criteria no 2 ( one normal pod on main stem that has reached its mature color) was useful predictor of the date of occurrence of PM. At PM the moisture content of individual seed was 55%. The average moisture content of all seed at P.M was 44% due to different maturity timing ( difference of 11 days) Criteria no 4,6,7,8 occurred at variable time periods from the point of PM for each cultivar. Harvest maturity (13% MC) occurred 10 to 13 days after physiological maturity.

27 Physiological maturity-Soybean Discussion Criteria no 3 ( pods free of green color) can be regarded as prediction of PM. The result also confirms the previous studies of loss of green color in pod as indicator of PM of entire soybean plant. The experiment is good, as it can be practically used in the field.

28 Seed maturity-Cabbage Introduction and Objective Immature seed contains high amount of chlorophyll. The chlorophyll content is broken down during the late stages of ripening process. Chlorophyll in the seed do not show variable fluorescence because the metabolism of the seed has stopped at the moment of acquisition of desiccation tolerance. Studies using CF have been conducted in beans, carrot, turnip and other crops for determining seed maturity and its effect in germination and storability. Such study was undertaken in cabbage to introduce a non- destructive and instantaneous method for determining the maturity and quality of Individual seed. Chlorophyll fluorescence of the testa

29 Seed maturity-Cabbage Chlorophyll fluorescence of the testa Figure 16. Schematic representation of the set up used for CF measurement. Chlorophyll a in the seed coat was excited by laser radiation (656 nm) and the resulting fluorescence filter 730 nm, than pass to lock- in Amplifier for measurement.

30 Seed maturity-Cabbage Chlorophyll fluorescence of the testa Based on the magnitude of CF signal, four subsamples were made- Low. Medium. High. Very high. The seeds after separation into subsamples were subjected for germination test as per ISTA, 1996.

31 Seed maturity-Cabbage Chlorophyll fluorescence of the testa Figure 17. chlorophyll content of seed

32 Seed maturity-Cabbage Chlorophyll fluorescence of the testa Figure 18. Different sub samples and germination performances

33 Seed maturity-Cabbage Result and Discussio n The germination performance was inversely related to the magnitude of the CF signal. The seeds from the subsample with the lowest CF signal germinated at 100% with 100% normal seedlings and had highest germination rate. The very high CF subsample had significantly reduced performance. It is useful as non-distructive marker of maturity and germination performance. It can be used in determining maturity and quality of all types of seeds for which the chlorophyll is broken down during the maturation process. Chlorophyll fluorescence of the testa

34 Physiological maturity-Sunflower Introduction and Objective Several studies have been conducted in determining sunflower PM based on visual character (color) but they are subjective and may vary with environmental conditions. This visual character have not been validated in terms of maximum fruit dry weight. Studies on relationship of MC at PM of sunflower have also been done but there is no appropriate model that matches fruit dry matter accumulation to fruit WC valid across different genotypes and growing conditions. There is no consensus about the effects of stress on grain WC at PM, although there has been report earlier that brief exposure to various types of stress have shown to alter grain growth dynamics.

35 Physiological maturity-Sunflower Introduction and Objective Therefore the study was conducted with the objectives of PM in sunflower coincides with fixed fruit WC which coincides with maximum fruit dry matter accumulation and to study the effect of brief exposure to high temperature stress on grain dry weight and fruit WC.

36 Physiological maturity-Sunflower Influence of fruit in capitulum in determining PM Flowering begins at periphery and progress towards center. It takes 5-12 days depending on total no of floral circle and genotypes. PM at periphery Is earlier than center. Figure 19. Flower arrangement and seed development in capitulum f

37 Physiological maturity-Sunflower Plants were grown in different condition (open field and green house). Sampling began at flowering and continued 30 days after PM (when final fruit weight did not increase). The fruit were harvested at 2-3 days interval from peripheral and intermediate positions on capitulum. Fresh (fruits weighed 3-5 minutes after harvest) and dry weight (48 h at 60 C) was determined. Fruit water content was calculated as the difference between fresh and dry weight and Fruit water concentration as the ratio between fruit water content and fresh weight expressed as percentage.

38 Physiological maturity-Sunflower Figure 20. Relationship between FDW and WC (triangles) during grain filling corresponding to peripheral fruits. The breakpoint between second and third section (equivalent to fruit WC at PM)did not differ between genotypes. Differences in FDW was observed between genotypes. Except HA89 other genotypes Showed similar fruit WC. This May be due to different fruit size, proportion of pericarp in The fruit.

39 Physiological maturity-Sunflower Figure 21. Relative FDW and WC for peripheral fruits At moisture content 38C all genotypes had maximum FDW which did not increase later.

40 Physiological maturity-Sunflower Determination of fruit dry weight and water concentration dynamics in intermediate fruits Figure22. Dynamics of FDW (square) and WC (circles) between peripheral (closed symbols) and intermediate (open symbols) Fruit at intermediate achieved lower FDW and reached PM later than fruit at peripheral. Fruit at intermediate had greater WC than peripheral at all times.

41 Physiological maturity-Sunflower Standardization of FDW and fruit WC Figure 23. Relative FDW and WC for peripheral and intermediate fruits At moisture content 38C all genotypes had maximum FDW which did not increase later

42 Physiological maturity-Sunflower Figure 24. Dynamics of fruit growth and fruit WC at PM exposed to high temperature.

43 Physiological maturity-Sunflower Yellow back with bracts beginning turn brown, PM White seed Gray seed Immature seed mature seed Figure 25. Picture of mature sunflower

44 Physiological maturity-Sunflower Result Fruit WC of 38% proved robust indicator of PM except for HA89 genotype. Fruit from intermediate position in capitulum started growing 3-5 days later than peripheral fruits and matured 3-8 days later. Exposure to stress condition like high temperature shortened grain filling duration by 2-4 days, decreased final fruit weight and increased fruit WC at P.M. At anthesis fruit WC was 89% and dropped continuously during grain filling and post PM periods. The Fruit WC at intermediate was higher than peripheral at all time from start of anthesis.

45 Physiological maturity-Sunflower Discussion Although there were difference in maturity level and FDW variation between intermediated and peripheral fruits but those were minimize by standardization using relative FDW of all genotypes. The relationship between Relative FDW and WC showed similar characteristic across position when fitted in tri-linear function. The work has been carried out in various conditions using all possible characteristic of sunflower development such as study on both peripheral and intermediate fruit maturity and in stress and non-stress condition.

46 Physiological maturity-Sunflower Discussion Random sampling of grain at water concentration of 38% involved only a small yield penalty (<5%) in both stress and unstressed condition. All genotypes except HA89 attained maximum fruit dry weight at water concentration 38%. The reason for variation in fruit moisture concentration in HA89 genotype is not clearly mention, it may be due to fruit size, propotion of pericarp in the fruit.

47 References Afuakwa, J. J. and R. K. Crookston Usuing the kernel milk line to visually monitor grain maturity in maize.Crop Sci. 24: Crookston, R. K., and D. S. Hill A visual indicator of the physiological maturity of soybean seed. Crop Sci. 18: Daynard, T. B and W. G. Duncan The black layer and grain maturity in corn. Crop Sci. 9: Gbikpi, P.J. and R. K. Crookstoon A whole-plant indicator of soybean physiological maturity. Crop Sci. 21: Jalink, H., A. Frandas, R. Van Der Schoor, J.B. Bino Chlorophyll fluorescence of the testa of Brassica oleracea seeds as an indicator of seed maturity and seed quality. Sci. agris., Piracicaba, 55: Rondanini, D. P., R. Savin, and A. J. Hall Estimation of physiological maturity in sunflower as a function of fruit water concentration. Europ. J. Agronomy 26: TeKrony, D.M., D. B. Egli, J. Ballas, T. Pfeifferet, and R. J. Fellows Physiological maturity in soybean. Agron. J. 71:

48 Thanks for your attention! Questions and comments are greatly appreciated!


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