Heliothermal Units Research Articles

Agrometeorological indices of white clover (Trifolium repens) in western Himalayas

Field experiments were conducted during 2009-2010 and 2010-2011 to study the growth performance of white clover (Trifolium repens L.) under different temperature regimes over the crop growth period. The agroclimatic indices for temperature viz., growing degree days (GDD), heliothermal units (HTU) and photothermal units (PTU) were computed for different phenological stages of the crop. Changes in weather parameters concomitant to different sowing time caused significant variation in the performance of the crop. The results indicated that the early sown crop had longer crop span (205 days) than the late sown (142 days). From emergence to seed maturity, white clover accumulated GDD of 2314±72 °C days, HTU of 17791±409 °C days hour and PTU of 29412±742 °C days hour, respectively. Positive correlations were found between fresh leaf weight, fresh stem weight and fresh root weight for GDD, HTU and PTU.

Accumulated heat unit requirement and yield of irrigated wheat (Triticum aestivum L.) varieties under different crop growing environment in central Punjab

Field experiment was conducted during rabi seasons of 2009-10 and 2010-11 to study the phenology, accumulation of growing degree days (GDD), helio-thermal unit (HTU), photo-thermal unit (PTU), pheno-thermal index (PTI) and performance of wheat (Triticum aestivum L.) varieties grown under different sowing dates. The crop sown on October 25 took maximum calendar days, growing degree days, photo-thermal unit and helio-thermal unit for 75% earing and maturity which got reduced significantly with subsequent delay in sowing time. The grain yield recorded in October 25 was statistically at par with November 5. The significant reduction in grain yield of timely sown varieties was recorded when sowing was delayed beyond November 15. Among the varieties ‘PBW 621’ recorded the highest grain yield which was statistically on par with ‘PBW 550’. The timely sown wheat varieties like ‘PBW 621’, ‘PBW 343’, ‘DBW 17’ and ‘WH 542’ took highest calendar days, GDD, HTU, PTU and PTI for earing and maturity. However, in medium duration varieties like ‘PBW 550’ the significant reduction was noticed when sowing was delayed beyond November 25. The variety ‘PBW 550" recorded the highest grain yield at November 15 sowing as compared to all other sowing dates.

Seasonal influence of flowering behavior and plant growth characters on parental lines of hybrid rice

Parental lines of hybrid rice-A lines (IR62829A and IR58025A), B lines (IR62829B and IR58025B), and R lines (IR10198-66-2R, AS 89044, and Pusa 150R)-were raised at monthly intervals from August 1994 to July 1995. The recommended cultivation practices were adopted and observations were made in 10 randomly selected plants from each population. During the cropping period, data on maximum and minimum temperature and hours of sunshine and daylength were obtained from agrometeorological documentation records. From this, heat unit concepts-growing degree days (GDD), relative temperature disparity (RTD), photothermal units (PTU), and heliothermal units (HTU)-were derived for correlation and regression studies. Variations were observed in different parameters, not only because of genotype characters and seasonal influence but also because of the interaction between them. Most floral characters were better expressed in the summer season (February to May) than in the samba season (October to January).

Growth and yield prediction of wheat in relation to agroclimatic indices under irrigated and rainfed condition

Field experiments were conducted during rabi season of 2005-06 and 2006-07 in irrigated as well as rainfed conditions under subtropical condition of Jammu with three cultivars (PBW-343, RSP-81 and Raj-3765) of wheat sown on normal dates of sowing with four replications. The different agroclimatic indices were derived at different phenophases. The results revealed that crop experienced 1670 oC day, 19584oC day hours and 10371oC day hours accumulated growing degree days (GDD), cumulative photothermal (PTU) and heliothermal units (HTU), respectively for attaining the maturity under irrigated conditions. The variety PBW 343 took higher thermal time (1602oC days) as compared to Raj 3765 (1576 oC days) and RSP81 (1574 oC days) for attaining physiological maturity. Maximum heat use efficiency (HUE) by variety PBW343 (5.87 kgha-1 oC days) was found under irrigated situation as compared to other cultivars. GDD was found best indices for prediction of phenology followed by PTU, HTU.

Quantification of growth and yield of oilseed Brassica using thermal indices under semi-arid environment

Field experiments were carried out at IARI research farm, New Delhi representing semi-arid climatic condition, to evaluate the growth and yield of oilseed Brassica using thermal indices. Two cultivars of Brassica juncea viz., Pusa Jaikisan and Varuna, widely grown in north and north-western parts of the country, were sown on ten different dates from 1st October to 3rd December at weekly interval. Three widely used thermal indices viz, growing degree days (GDD), heliothermal units (HTU) and photothermal units (PTU) were computed up to maximum biomass production in both the seasons. It was observed that GDD was able to explain variation in biomass, seed yield and oil content to the tune of 75, 66 and 78 per cent while PTU could explain 73, 66 and 77 per cent variations respectively. The yields and oil content of these two cultivars were highly influenced by the differential thermal environment and delay of sowing; decreased seed yield and oil content significantly.

Heat unit utilization of kharif maize in transitional zone of Karnataka

A field experiment was carried out during kharif seasons of 2005 and 2006 to study the effect of heat and thermal unit use of maize cultivars in red sandy loam soil at Zonal Agricultural Research Station, Shimoga (Karnataka, India). The experiment consisted of three dates of sowing viz., first fortnight of June, second fortnight of June and first fortnight of July with six cultivars viz., two double cross hybrids (All-rounder and 30 R-77), two single cross hybrids (NAH-2049 and 30 V-92) and two composites (NAC-6004 and NAC-6002) was laid out in split-plot design replicated thrice. Higher heat use efficiency was recorded with the crop sown in first fortnight of June and decreased with each delay in sowing. Grain yield of maize was found inversely related to the helio-thermal units. Thus, early sowings escape adverse situation during its life cycle in maize.

Growth and earliness of Chinese cabbage (Brassica rapa var. chinensis) as a function of time and weather conditions

Abstract The aim of the research, which was carried out in the years 2003-2005, was to assess the possibility of creating regression models for the earliness of Chinese cabbage (Brassica rapa var. chinensis, pak choy) plants cultivated under field conditions during the summer-autumn months. Four variables were chosen for developing the prediction model: the minimum, mean and maximum air temperatures and sunshine hours. After stepwise regression analysis, it was noted that crop earliness could be described as a function of mean air temperature and sunshine hours. For this model, the coefficient of determination R2 was equal to 0.962. Additional models based on various thermal indices - growing degree days (GDD), heliothermal units (HTU) and photothermal units (PTU) - were also constructed and taken into consideration. The linear regression equation that includes GDD could only simulate the earliness of the plants with a precision below 14%. The model built on the basis of PTU showed a better fit of the predicted data to the observed data (around 49%), while the last model, which incorporated HTU, was the most accurate (R2 was equal to 0.843). Models for the growth of pak choy plants in the field based on a time variable are also presented in this paper.

Modulation of wild marigold (Tagetes minuta L.) phenophases towards the varying temperature regimes – a field study

Field experiments were conducted during 2007 and 2008 at experimental farm of Institute of Himalayan Bioresource Technology, (CSIR) Palampur (HP), India to study the performance of wild marigold (Tagetes minuta) under changing temperature regimes over the crop growth period. The established agroclimatic indices for temperature studied elsewhere in the domain viz., relative temperature disparity (RTD), growing degree days (GDD), heliothermal units (HTU) and photothermal units (PTU) were computed for different varied dates of sowing the crop. Distinct changes in weather parameters concomitant to different sowing time consequently caused significant variation in the performance of the crop. The results indicated that the early sown crop had longest crop span (224 days) than the late sown crop (102 days), from sowing to harvesting. The mean GDD accumulation from sowing to harvest ranged from 1378 to 2518°C days HTU from 6781 to 15706°C days hour and PTU from 17400 to 33052°C days hour. Total biomass, and content and yield of essential oil were correlated with different heat units calculated during the crop growth seasons. All the agroclimatic indices had positive correlations with biomass, oil content and oil yield. Thus, these indices seem to be effective in taking into account and expressing the effect of varying ambient temperature on the duration between the phenological events for comparing the crop response to the ambient temperature between different phenological stages.

Agrometeorological indices in relation to phenology of aerobic rice

Field experiment was conducted during kharif seasons of 2003 and 2004 at College farm, College of Agriculture, Rajendranagar, Hyderabad to study the phenology and, heat and radiation use efficiency in aerobic rice. Crop was sown on four different dates viz., 16 June, 26 June, 07 July and 18 July as main plots and two varieties viz., Jagtiala Sannalu and Polasa Prabha as sub-plots in split plot design and replicated thrice. Results revealed that, from emergence to physiological maturity, Jagtiala Sannalu has accumulated mean growing degree days of 2017+55 and heliothermal units of 11526+817 with coefficient of variation of 3% and 7%, respectively. While Polasa Prabha has accumulated 2102+33 mean growing degree days and 12031+716 heliothermal units from emergence to physiological maturity with coefficient of variation of 2 % and 6%, respectively. In both the cultivars i.e.,Jagtila Sannalu and Polasa Prabha higher heat use efficiency (6.61 and 6.29), heliothermal use efficiency (1.30and 1.19) and radiation use efficiency (6.28 and 5.88) were obtained in crop sown on 16 June. In Jagtila Sannalu and Polasa Prabha, physiological maturity can be predicted using AGDD HTU which accounted for 84% and 86% varibility.

Heat unit requirements for phenophases of wheat genotypes as influenced by sowing dates

A field experiment was carried out during winter season of 2002-2003 and 2003-2004 on the silty loam soil at Faizabad (U.P.) with three wheat genotypes viz, HUW-234, HD-2285 and HP-1633 sown at three different times viz., 5 November, 20 November and 5 December to assess the Heat unit requirements for phenophases of wheat genotypes as influenced by sowing dates. Results revealed that wheat sown on 5 November and 20 November recorded higher accumulated GDD, Heliothermal units, photothermal units and phenothermal index at all the phenopheses over sowing done on December 5th in which higher yield of wheat. Higher thermal units under 5 November and 20 November sowing were not found conducive for a better yield of wheat crop. Lesser value of cumulative PTI during crop period produces higher grain yield in December 5th sowing.

Patrón de crecimiento de pasto buffel [Pennisetum ciliare L. (link.) sin. Cenchrus ciliaris l.] en Tamaulipas, México

The purpose of this research was to learn on the crop growth rate (CGR), leaf area index (LAI), leaf:stem (LS) ratio, and the dead tissue:live tissue (DL) ratio of buffelgrass [Pennisetum ciliare L. (Link.) Syn. Cenchrus ciliaris L.], as functions of rainfall (precipitation, i.e.: PREC), soil moisture at 20 (SM20) and 40 (SM40) cm, growing degree days (GDD), solar radiation, heliothermal units, and evapotranspiration. From July 1999 to December 2000, five time-overlapped cut programs were designed in order to perform weekly pasture harvests, under a 3-replicate, randomized block design. Multivariate analysis as principal components and conglomerate analyses together with regression analysis were performed. Eighty five (85) percent variability could be explained by three principal components. Three treatment groups were formed (P<0.01). Group 1: spring/late-fall harvests showing moderate CGR (16.36±14.38 kg ha-1 d-1) limited by SM20 and GDD. Group 2: summer harvests with 28.56±23.3 kg ha-1 d-1 (CGR), 1.49±0.7 (LS) and 0.64±0.4 (LAI) restricted by PREC. Group 3: winter harvests with 5.1±7.8 kg ha-1 d-1 (CGR), limited by GDD and SM20. SM20 explained 87 %, and PREC explained 92 % of CGR variation for Groups 1 and 2, respectively. Spring growth rates could not be predicted since no rainfall events were recorded in that time, during the studied period. Under the conditions of this study, it is possible to predict buffelgrass growth rates during summer and fall.

Pre-harvest wheat yield prediction using agromet-spectral-trend-yield models for hoshiarpur and rupnagar districts of punjab

Wheat yield prediction using different agrometeorological indices, spectral index (NDVI, Normalized Difference Vegetation Index) and trend predicted yield (TPY) were developed in Hoshiarpur and Rupnagar districts of Punjab. On the basis of examination of Correlation Coefficients (R), Standard Error of Estimate (SEOE) and Relative Deviation (RD) values resulted from different agromet models, the best agromet subset were selected as Minimum Temperature (Tmin), Maximum Temperature (Tmax) and accumulated Heliothermal Units (HTU) in case of Hoshiarpur district and Minimum Temperature (T--min), accumulated Temperature Difference (TD) and accumulated Pan Evaporation (E) for Rupnagar district at reproductive stage (2nd week of March) of wheat. It was found that Agromet-Spectral-Trend-Yield model could explain 96 % (SEOE = 87 kg/ha) and 91 % (SEOE = 146 kg/ha) of wheat yield variations for Hoshiarpur and Rupnagar districts, respectively.

Heat unit requirement, radiation, water use and photoperiod during the growing season of toria (Brassica campestris variety toria)

The agrometeorological data of toria (variety M-27) at Jorhat and Shayamakhunta for the period 1986-87 to 1992-93 were used for assessing phenological development in relation to heat unit, water use, photothermal and heliothermal unit and photosynthetically active radiation (PAR) requirement at Shayamakhunta and Jorhat. Photothermal, heliothermal unit, water use and PAR were higher at Shayamakhunta than that of Jorhat. Heat use efficiency (HUE) and radiation use efficiency (RUE) also showed variations in time and space which were comparatively higher in early sown crops. A curvilinear relationship between duration (days) and heat units was derived seperately for sowing to flowering and pod formation to physiological maturity stages which showed consistent positive correlations at both locations.

The effect of planting date and nitrogen management on yield and quality of aromatic rice (Oryza sativa)

Growth environment and plant nutrition are two important factors influencing growth, yield and quality of aromatic rice (Oryza sativa L.). The present study was conducted at Kalyani, India to determine the effect of two planting dates and four fertilizer levels on different aromatic rice cultivars during the dry seasons of 1995/96 and 1996/97, while nine cultivars were evaluated during the wet seasons of 1996 and 1997. Thermal and photoperiodic conditions significantly influenced the vegetative (leaf area index and light extinction co-efficient) and reproductive (filled spikelets/panicle) growth of the crop. Delayed planting (23 February) significantly reduced the grain yield by 0·88 t/ha, amylose content by 0·5% and duration by 10 days; but increased the summed heliothermal units (17806 v. 18505). Thus, the cultivars became less efficient (27%) in heat use with delay in planting from 2 to 23 February. Relative availability of NH4+-N from urea and Azolla influenced the crop growth (leaf area index [LAI], tiller production and leaf chlorophyll content) and nutrient uptake. Supply of inorganic N either alone or in conjunction with Azolla significantly increased grain yield (18–41%) and protein content (0·1–0·7%) over 15 t/ha of Azolla alone. However, combined application of Azolla and urea lowered the amylose content below that achieved by application of either substance alone. Correlation studies among quality attributes indicated that long-grained varieties had lower head rice recovery (r=−0·69) due to more breakage during milling and greater test weight (r=0·93).

Effect of date of planting and harvesting schedule on heat-unit accumulation and biomass production in Japanese mint (Mentha arvensis)

The present investigation was carried out during the spring season of 2010 and 2011 at Ludhiana, Punjab, to study the effect of heat-unit accumulation on herb and oil productivity of Japanese mint (Mentha arvensis L.) under different dates of planting and harvesting schedules. The field experiment was laid out in split-plot design keeping 4 dates of planting 1 January, 15 January, 30 January and 15 February in main plots and 3 harvesting schedules (120, 135 and 150 days after planting) in subplots. Japanese mint planted on 15 February recorded the maximum fresh-herb and oil yields, which were statistically at par with that planted on 30 January, but were significantly higher than 15 January and 1 January plantings. The crop planted on 30 January and 15 February accumulated 456 and 624 and 222 and 390 units higher growing degree-days (GDD) than 1 January and 15 January planted crop respectively. The fresh-herb and oil yield of mint increased successively and significantly with delay in har- vesting from 120 to 150 days after planting (DAP). The growing degree-days (GDD), photothermal units (PTU) and heliothermal units (HTU) accumulation were 649, 8,866 and 5,275 and 322, 4,480 and 2,548 units higher in crop harvested at 150 DAP than that harvested 120 and 135 DAP respectively. The interaction effects revealed that crop planted on 15 February and harvested at 150 DAP gave the maximum biomass and oil yield, which were sta- tistically at par with that planted on 30 January and harvested at 150 days after planting, but was significantly bet- ter than all other combination because of higher accumulation of GDD, HTU and PTU. The multiple regression model was found to be well fit with P=0.0006, which revealed that fresh- herb yield of mint was significantly and positively correlated with GDD, HTU and PTU at multiple correlation value of 0.9636.

Microclimate variations in relation to different types of polyethylene-film mulch on growth and yield of groundnut (Arachis hypogaea)

A field investigation was conducted at Vridhachalam in Tamil Nadu during post- rainy seasons of 2001 -02 and 2002-03 to study the microclimatic variation in relation to different types of polyethylene-film mulch and its effect on the growth and yield of groundnut (Arachis hypogaea L.). Results revealed that, irrespective of the colour, plastic- film mulch significantly increased the soil temperature (1 .O-1 .gC) at different phenophases of crop growth from sowing to harvest. The soil temperature was higher under black-film mulch, followed by transparent - and white- polyethylene film mulches among the different mulches evaluated. The soil temperature under ridges-and-furrows land configuration was 0.3OC lesser than flat-bed and broad-bed furrow methods. Growing degree-days (GDD) and helio-thermal unit (HTU) did not show much variation between the different types of polyethylene films up to 80 days after sowing (DAS). However, heat unit efficiency (HUE) differed significantly among different types of plastic mulches but there was no such significant difference between the for soil temperature, GDD, HTU and. HUE. The dry-matter production and yield attributes were significantly higher under black polyethylene-film mulch which gave the highest pod yield of 2.87 Uha compared with 2.21 tlha by the non-mulched control. Hence black polyethylene film mulch in groundnut with adoption of flat-bed system of land configuration could be an important agricultural practice to augment groundnut productivity besides improving microclimatic conditions.

Effect of different microenvironment on heat unit requirement and heat use efficiency of different lentil genotypes sown in rice fallow condition

To utilize the rice (Oryza sativa L.) fallow land of the northeastern region (NER) of India and enhance the crop- ping intensity, a set of lentil (Lens culinaris) genotypes/varieties were evaluated for heat requirement and use effi- ciency under 2 thermal regimes in Tripura [altitude of 52 m ASL (meter above sea level)] during 201415 and 2015-16 (November to March). The experiment consisted of 14 lentil genotypes namely HUL 57, L 4076, ILL 10897, ILL 10893, BM 6, BM 7, WBL 77, Subrata, ILL-6002, L-1111-12, L-1112-18, L-1112-20, ILL- 10951, and L 1112-07 which were sown under two thermal regimes e.g., 16th November (1st date of sowing) and 1st December (2nd date of sowing) during both the years. Results revealed that crop sown on 16th November took 3 days more than that of 1st December sowing to attain physiological maturity. Lentil L-1112-18 took a minimum number of days (80) to reach physiological maturity stage followed by L-1111-12 (82 days). Crop sown on 1st De- cember consumed more growing degree days (GDD) between different phenological stages, for example sowing to 50% emergence (113.8), 1st flower bud initiation to 50% flowering (250.4), and 50% flowering to physiological maturity (632.3) except for 50% emergence to 1st flower bud initiation (682.4) than that of 16th November sowing. Lentil variety HUL 57 required the highest GDD between all the phenological stages. Accumulated GDD and heliothermal unit (HTU) were higher for 16th Nov sowing ranged from 100.4 C days (emergence) to 1719.5 C days (physiological maturity) and accumulated HTU from 127.6 C day hours (emergence) to 2199.2 C day hours (physiological maturity) than 1st December sowing. HUL 57 accumulated the highest GDD and HTU from sowing to physiological maturity. The pheno-thermal index (PTI) was higher between sowing to 50% emergence (20.2-21.8) and 50% flowering to physiological maturity (18.2-20.1) than in between of 1st flower bud initiation to 50% flowering (16.2-17.4) and 50% emergence to 1st flower bud initiation (16.5-17.9). Lentil HUL 57 had the highest PTI (21.3) followed by L-4076 (21.0) while the lowest PTI was by BM 6 (16.1) followed by L-1112-18 (17.1) between 50% flowering to physiological maturity. Lentil sown on 16th Nov produced more seed (1008.9 kg/ha), straw (1608.9 kg/ ha), and biomass (2617.6 kg/ha) yields, and improved heat use efficiency for grain yield (0.60 kg/ha C day-1) and biomass yield (1.56 kg/ha C day-1) than that of sowing on 1st Dec. Lentil genotype BM-6 produced maximum seed yield (1270 kg/ha) followed by WBL 77 (1234 kg/ha) and L-1112-18 (1231.5 kg/ha). The highest straw yield was produced by WBL 77 (1747.5 kg/ha) followed by L-4076 (1715.5 kg/ha) and L-1112-18 (1685.5 kg/ha). However, genotype L-1112-18 produced maximum biomass yield (2917 kg/ha) followed by L-1111-12 (2894.5 kg/ha) and L- 4076 (2883 kg/ha). The genotype L-1112-18 had maximum heat use efficiency for seed yield (0.90 kg/ha C day-1) and biomass yield (2.12 kg/ha C day-1). Thus, the study recommended the genotypes BM-6, WBL 77, and L-1112- 18 which are heat efficient and high yielding for efficient utilization of rice fallow areas under both the thermal re- gimes.

Introduction of multipurpose agro-industrial crop quinoa (Chenopodium quinoa) in western Himalayas

Two accessions of quinoa (Chenopodium quinoa Willd.) were introduced in mid-hills of the western Himalayas for the first time during 2016 and an experiment was conducted at Palampur, Himachal Pradesh, to study the ef- fect of sowing time on growth, quality parameters and yield. The crop took 129 to 159 days for maturity and per- formed well under mid-hill conditions. Accumulated growing degree-days (AGDD) ranged from 512 to 2,432, ac- cumulated photothermal units (APTU) from 5,595 to 31,705 and accumulated helio-thermal units (AHTU) from 3,942 to 18,183 during seed sowing to maturity, respectively. Agrometeorological indices showed a positive corre- lation with growth and yield attributes. Significantly higher plant height was recorded on 30 January sown crop. The highest seed yield was recorded when the crop was sown on 30 January, being 10.48% and 19.63% higher than those sown on 15 February and 15 January, respectively. Protein content in quinoa seed ranged from 18.1 to 21.6% and was significantly higher when the crop was sown on 15 February. Carbohydrate concentration ranged from 65.3 to 67.6% and it was significantly higher in IHBT/Q2 accession. Other nutrients were present in permis- sible limits. The results showed that the nutritional potential of quinoa seeds is a good source of protein and min- erals, and quinoa can be grown as successful crop under mid-hills of the western Himalayas.

Accumulated Heat Unit and Phenology of Wheat Cultivars as Influenced by Late Sowing Heat Stress Condition

Accumulated heat unit and phenology of wheat (Triticum aestivum L.) cultivars were studied under normal and late sowing heat stress conditions by seeding them on November 30 and December 30, 2006. November 30 sowing was considered as normal sowing condition, whereas December 30 sowing was regarded as late sowing heat stress condition. Four heat tolerant wheat cultivars, Gourab, Sourav, Kanchan and Shatabdi and two heat sensitive cultivars, Sonora and Kalyansona were used as study materials. The results indicated that the number of days required to attain different phenological stages with late growing condition. For all the phenological stages plants of normal sowing condition needed higher heat units than the late sowing condition. At the earlier phenological stages phenothermal indices decreased with late sowing compared to normal sowing but increased at the later stages. At normal sowing condition all the cultivars showed higher heat use efficiencies compared to late sowing condition. The heat tolerant cultivars, Gourab, Sourav, Kanchan and Shatabdi exihited better performance in phenology, growing degree day, helio-thermal unit and finally used heat more efficiently than the heat sensitive cultivars, Sonora and Kalyansona. Key words: Wheat, phenology and heat use efficiency. DOI: 10.3329/jard.v7i1.4422 J Agric Rural Dev 7(1&amp;2), 57-64, June 2009