Review and Progress

Microclimatic modification in crops-a review  

KRISHNA SURENDAR KARUPPASAMY
Regional Research Station, Tamil Nadu Agricultural University, Paiyur, Krishnagiri District, Tamil Nadu, India
Author    Correspondence author
Plant Gene and Trait, 2016, Vol. 7, No. 14   
Received: 25 May, 2016    Accepted: 30 Jun., 2016    Published: 21 Nov., 2016
© 2016 BioPublisher Publishing Platform
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract

Micro climate is the climate of small area that results from the way the geometry or physical properties of those areas modify the general climate. It differs from macro climate, which prevails above the first few meters over the ground, primarily in the rate at which changes occur with elevation and with time. Whether the surface is bare or vegetated, the greatest diurnal range in temperature experienced at any level occurs there. Temperature changes drastically in the first few ten of millimeters from the surface in to the soil or into the air. Changes in humidity with elevation are greatest near the surface. Very large quantities of energy are exchanged at the surface in the processes of evaporation and condensation. Wind speed decreases markedly as the surface is approached and its momentum is transferred to it. Thus it is the greatest range in environmental conditions near the surface and the rate of these changes with time and elevation that make the microclimate so different from the climate just a few meters above, where atmospheric mixing processes are much more active and the climate is both moderate and more stable.

Keywords
Microclimate; Crop geometry; Temperature; Wind speed

Introduction
In general “the climate experienced in a valley of small area when compared to that experienced over the entire mountain” is referred to as microclimate in meteorological parlance. However, the microclimate of the crop is defined as “the climate near the ground in which the plants live”. It is customary to divide atmospheric phenomena in various scales. The terms macro-meso-and micro-scale are arbitrarily used depending upon the user. The summary of scales in time and space space listed by Wieringa and Lomas (2001) as below gives us a comprehensive idea of the different scales to be adopted by agricultural meteorological personnel.
 
1 Result and Discussion
Ornamental plants show considerable diversity in their growth habits, colors, blooming structure, flower shape and size (Pasha et al., 2015) Hence the performance of a cultivar in respect of growth and yield is known to be greatly influenced by the environmental conditions particularly integrated temperature and light (White and Warrington, 1988, Hodges, 1991). Growth and development of bulbous plants are mainly affected by seasonal thermo periodicity, constituting the basis of the techniques used to control flowering during forcing (Rees, 1992). In some bulbous species daily thermoperiodic changes are required to induce flowering (Halevy, 1990). Analyses of variance showed highly significant results for all the studied traits of gladiolus plants. Corm diameter was the only trait which showed non-significant results. Variety×climate interaction was also found significant (Table 1). The results regarding effect of different climatic conditions on all the studied traits of three gladiolus cultivars are given as treatment means (Figure1 and Figure 2). 
 
1.1 Effect of different Agro-ecological conditions on vegetative growth of Gladiolus
Plants have to face various environmental stresses simultaneously, which affect their growth and development severely (Ahmad et al., 2015). The response of three gladiolus varieties with respect to their vegetative growth under the environmental conditions of Faisalabad and Rawalakot are given (Table 2). From the data it is concluded that temperature is an important factor for the vegetative growth of this flowering plant. Therefore Days to germination (11.13) and germination percentage (93.31%) was best under Faisalabad climatic conditions while at Rawalakot due to low temperature more number of days (13.43) was taken for to sprouting (Table 2). 
 
Early germination at high temperature is also reported by (Hartmann et al., 1981). Due to low temperature during germination, under Rawalakot climatic conditions germination percentage also remained low (85.8%). High sprouting percentage at Faisalabad might be due the fact that the environmental conditions were favorable for the sprouting at that time when the temperature was higher (Figure 3). As the varieties are concerned at Faisalabad conditions maximum germination percentage was observed in White prosperity while at Rawalakot maximum germination percentage was observed in rose supreme. Carpenter et al. (1995) also reported that temperature between 20˚C to 25˚C promoted germination to 97% in gladiolus. The traits Plant height and Number of leaves plant-1 were best under Rawalakot climatic conditions. At the Faisalabad plant height was recorded 90.2 cm whereas under Rawalakot climatic conditions it was 107 cm. Maximum plant height was recorded in the variety Rosesuoreme at Rawalakot, whereas minimum plant height was recorded in the variety Amsterdam at Faisalabad. 
 
The increase in plant height of gladiolus at high temperature is also reported by Gursan (1993). At Rawalakot 8.45 number of leaves plant-1 were obtained whereas under Faisalabad climatic conditions 6.78 number of leaves was counted. Highest number of leaves per plant at Rawalakot was formed during high temperature 23.18˚C and minimum number of leaves per plant was observed at Faisalabad where temperature was14.3˚C during vegetative growth. Rose supreme produced maximum number of leaves at Rawalakot and at Faisalabad Amsterdam produced minimum number of leaves. The results are in line with the findings of (Kishan et al., 2005) and (Bose et al., 1981) who reported maximum number of leaves in plants grown under warmer temperature and long day lengths. 
 
1.2 Effect of different climatic conditions on flowering of Gladiolus
Earlier researchers have reported that temperature is an important determinant for the rate of plant
development under climatic changes (Craufurd and Wheeler, 2009). The response of three Gladiolus varieties viz. Amsterdam, White Prosperity and Rosesupreme with respect to their flower indices under both environmental conditions (Table 3). During flowering stage average temperature was recorded high (23.18˚C) at Rawalakot where as it was observed (14.3˚C) at Faisalabad (Figure 3).
 
The results regarding effect of different climatic conditions on days to spike emergence of three cultivars of gladiolus (Table 3) which shows that different climatic conditions of the Faisalabad and Rawalakot have a significant effect on days to spike emergence of Gladiolus varieties. At Rawalakot 75.4 days were taken to spike emergence whereas at Faisalabad it took 81.8 days. Minimum number of days to spike initiation at Rawalakot climatic conditions might be due the fact that the environmental conditions were favourable for floral growth at that time when temperature at Rawalakot was higher than Faisalabad. At Faisalabad the temperature was lower due to which maximum number of days to spike initiation was obtained. The variety White prosperity took the minimum number of days to spike initiation at Rawalakot and at Faisalabad Amsterdam got maximum number of days to spike initiation. The early spiking of gladiolus was observed during high temperatures, which promoted quicker transition from the vegetative state to the reproductive state. Early spiking at high temperature is also reported by Halevy (1985) who stated that gladiolus flowered more rapidly under warm temperatures regardless of photoperiod. The results are in accordance with the finding of Piringer and Borthwick, 1961 who reported increase in the number of days to inflorescence formation in gladiolus under lower temperatures. 
 
At Faisalabad 40.9 cm of spike length was achieved whereas at Rawalakot 46.3 cm was obtained. Among the varieties under high temperature at Rawalakot the Rose supreme got the maximum spike length (48.3 cm) as compare to white prosperity and Amsterdam whereas at Faisalabad under` low temperature Amsterdam showed minimum spike length (35.7 cm) as compare to White prosperity and Rosesuoreme. Shortening of gladiolus spike at low temperature is also reported by (McCalla et al., 2011). At Rawalakot 8.03 mm spike diameter were recorded and 6.98 mm spike diameter were recorded at Faisalabad. Rose supreme produced maximum spike diameter at Rawalakot while at Faisalabad Amsterdam produced minimum spike diameter. The results are in line with the findings of Pasian and Lieth (1994) who reported low temperature causes reduction in spike diameter and length. At Rawalakot 13.11 number of florets was recorded while at Faisalabad 10.75 number of floret were obtained. Highest number of florets (14.20) was recorded in the variety Rosesupreme at Rawlakot, whereas the lowest number of florets (12.40) was recorded in the variety Amsterdam at Faisalabad. The results are in conformity with the results of Larson (1992) who reported the decreased number of florets per spike at low temperature. At Rawalakot 74.04 mm diameter of florets was observed while at Faisalabad 62.26 mm diameter of floret was observed. Among the varieties at Rawalakot Rosesupreme showed maximum diameter of floret while at Faisalabad Amsterdam showed minimum diameter of floret (Table 3,Table 2 and Table 4). Increase in floret diameter at high temperature is also reported by Gill et al., (2003) who reported increased diameter of the first floret during high temperature in early planting dates as compared to inflorescences obtained at low temperature during later dates of planting. 
 
In Rawalakot climatic conditions 50.12 g fresh weight of the spike was found whereas at Faisalabad 39.36g fresh weight of spike (g) was recorded. Rose supreme showed the best results regarding the fresh weight of spike at Rawalakot while minimum fresh weight of spike at Faisalabad was shown by Amsterdam (Table 3,Table 2). The results are in accordance with Kamble (2001). The results are in line with the findings of (Ko et al., 2005) who reported increased fresh weight of chrysanthemum flower at 17˚C as compared to 21˚C in a winter greenhouse experiment. At Rawalakot climatic conditions 14.28 g dry weight of spike was found whereas at Faislabad10.13 g dry weight of spike (g) was observed. Best results regarding the dry weight of spike at Rawalakot the variety Rosesupreme proved to have maximum dry weight while in Faisalabad Amsterdam has minimum spike dry weight. The results are in line with the findings of Bose and Tripathi (1996) who reported increased dry matter production at high temperature may be attributed to greater accumulation of photosynthates by vegetative parts in gladiolus.
 
1.3 Effect of climatic conditions on corms and cormels growth among three verities of Gladiolus
Corm size is a major factor to determine the capacity of bulbous plants to flower (Le Nard and De Hertog, 1993). Difference in corm size is responsible for the wide differences reported in the time of flower initiation and flowering in different places (Koul and Farooq, 1984, Negbi, 1999). Flower formation is directly related to the corm size (Negbi et al., 1989; De Mastro and Ruta, 1993) and a quantitative relationship between these two parameters was found by (Negbi et al., 1989). It is observed that under Rawalakot climatic conditions corm and cormels growth was better as compare to growth under Faisalabad climatic conditions (Table 4). 
 
During corm and cormels growth temperature was higher (24.95˚C) at Rawalakot as compare to Faisalabad where it was (10.02˚C). At Rawalakot 5.94 cm corm diameter was recorded whereas at Faisalabad 5.03 cm corm diameter was recorded .Rosesuprem obtained maximum corm diameter at Rawalakot while at Faisalabad revealed minimum diameter. The results are in line with the findings of Parker and Borthwick (1951) who reported an increase in corm diameter at high temperature in part to the production of more photosynthates. At Rawalakot climatic conditions 55.62 g corm weight was recorded whereas at Faisalabad 50.72 g corm weight was recorded. The minimum corm weight (g) at Faisalabad was observed during low temperatures (10.02˚C), while maximum corm weight at Rawalakot was observed during high temperature (24.95˚C). At Rawalakot maximum corm weight was found in Rose supreme while at the Faisalabad minimum weight of corm was observed in Rosesupreme. The results are in line with the findings of Shilo and Halevey (1981) who reported increase in corm weight at high temperature and long day lengths. 
 
At Rawalakot, it took 28.76 number of cormels clump-1 while 26.17 number of cormels clump-1 were obtained at Faisalabad. Highest number of cormels was recorded in the variety White prosperity at Rawalakot, whereas lowest number of cormels was recorded in the variety Amsterdam at Faisalabad. The results are in line with the findings of Laskar and Jana (1994) who reported an increase in gladiolus cormels production at slightly high temperature. At Rawalakot 8.58 g cormels weight was recorded while at Faisalabad 6.84 g weight of cormels was recorded. Among the varieties at Rawalakot in White prosperity obtained the maximum weight of cormels while at Faisalabad Amsterdam obtained minimum number of cormels. The results are in line with the findings of Laskar and Jana (1994) who reported an increase in gladiolus cormels production at slightly high temperature. 
 
2 Conclusion 
Plantation under Faisalabad climatic conditions took minimum days to sprouting (11.13 days) and had maximum sprouting percentage (91.30 %). The ideal temperature for sprouting was 26.5 ○C. Among the varieties Amsterdamperformed the best in days to germination (9.63) while in germination % age White prosperity (97.66) performed the best. The results regarding days to spiking (75.4 days), spike length (46.3 cm), spike diameter (8.030 mm), number of florets per spike (13.11 florets), diameter of florets (74.04 mm), fresh weight of spike (50.12 g) and dry weight of spike (14.28 g) was the best under  Rawalakot climatic condition. As for as varieties were concerned, white prosperity produced flowering in (77.7) days, maximum numbers of florets (14.20), maximum spike length (48.3 cm), fresh weight of spike (55.10 g), dry weight of spike (16.32 g), maximum spike diameter (8.21 mm) and floret diameter (77.65 mm) was observed to be the best in Rosesupreme cultivar under Rawalakot. The parameters like maximum corm diameter (5.94 cm) and corm weight (55.62 g), number of cormels (28.76) and cormel weight (8.58g) were the best under Rawalakot. The variety Rosesupreme gained maximum corm diameter (6.34 cm) and corm weight (58.33 g), White prosperity produced the maximum number of cormels (31.66) and cormels weight (9.34 g) at Rawalakot. From all above information, it can concluded gladiolus can be grown in Faisalabad during winter and in Rawlakot during summer with marketable quality, so gladiolus production throughout the year is possible however Rawalakot climatic conditions are more favorable for quality cuts.
 
3 Materials and Methods
The present study was conducted under the Agro-climatic conditions of Faisalabad and Rawalakot. Three Gladiolus cultivars namely, Rose supreme, Amsterdam and White prosperity were used for the present research. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. Uniform agronomic practices were applied to all three cultivars. Ten plants from each of the entry were selected randomly and data was recorded for morphological traits i.e. Days to Germination, Germination Percentage, Plant Height (cm), Number of Leaves, Days to Spiking, Length of Spike (cm), Diameter of Spike (cm), Diameter of Florets (mm), Number of Floret Spike-1, Fresh Weight of Spike (g), Dry Weight of Spike (g), and corm indices i.e. Diameter of Corms (mm), Weight of Corms (g), Number of Cormels, Weight of Cormels (g). Complete data was analyzed statistically by using analysis of variance technique and treatment means were compared through LSD test at the 5% level of significance according to (Steel et al., 1997). Before starting to experiment, soil samples from various blocks of experimental field in Faisalabad and Rawalakot were collected randomly to assess physio-chemical properties (pH, EC, texture, organic matter contents and N, P, K and Zn contents) of the soil. Soil analysis was performed to examine physical and chemical properties of soil. The results regarding physio-chemical analyses of soil from both ecological conditions are given below.
 
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