The basic principle of crop regulation is to manipulates the natural flowering and fruiting of guava plant in desired season of the year that contribute to increased fruit yield, quality, profitability and sustainability of the environment by reducing the use of the frequency of the pesticides. This concept is based on the fact that guava flowers are borne only on new, succulent, vigorously emerging vegetative growths. These new growth flushes can be either new emergences of lateral bud on older stems or extensions of already established terminals of various size and vigor. The crop regulation can be achieved by the adoption of the various practices like withholding irrigation after harvesting during the months of April-May in Northern Indian plains. This results in the shedding of flowers and the tree goes to rest. The basin of the tree is dug up, manured and irrigated in June. After about 30-35 days the tree put forth profuse flowering and fruit mature in winter. Terminal portion of the shoots up to 20 or 30 cm length should be pruned between 20th to 30th April. Always avoid severe pruning in guava. Apply the recommended dose of fertilizers during the month of June to encourage vegetative growth in July-August for getting maximum flowering during August-September for winter season crop. To regulate the guava crop, it is essential to reduce the fruit set during the rainy season and subsequently increase the fruit set during winter season by the use of different chemicals like NAA ethereal and urea etc.&nbsp;

Crop regulation in guava-A review

<div style="text-align: justify;">Guava (Psidum guajava L) is one of the most promising fruit crops of India and is considered to be one of the exquisite nutritionally valuable and remunerative crops. In recent years guava is getting popularity in the international trade due to its nutritional value and processed products. It is hardy, prolific bearer and highly remunerative fruit crop. Its cultivation is done on the commercial scale. There are mainly three bahar season of the guava fruit viz., Ambe bahar, Mrig bahar and Hasth bahar. Continuous bearing results in reduction of yield with small size fruits. The heaviest flowering is observed in rainy season cropping, but, the fruits of this season crop are rough, insipid in taste, poor in quality, less nutritive and are heavily attacked by many insects, pests, and diseases. In order to overcome this problem and to force a full crop in any of the three seasons, as required by the grower and the traders, bahar treatment is practiced. The main objective of crop regulation is to force the tree for rest and produce profuse blossom and fruits during any one of the two or three flushes. The methods to be followed for crop regulation depend on climatic factors, cropping pattern, extend of the damage by the disease and pests, market and industry demand, cultivar, etc. Crop regulation is achieved by the various techniques like water management to induce stress, pruning of shoots and roots at different levels and at different times, training of shoots and manual or chemical thinning of flowers.&nbsp;</div>

<div style="text-align: justify;">Crop Regulation in Guava: A Review</div>

<div>Background: Pigeonpea being highly branching and indeterminate growth habit responds very well to crop geometry. Hence to achieve potential yields, it is important to maintain optimum plant population which can effectively utilize available moisture, nutrients and solar radiation. The plant growth regulators are also known to enhance the source sink relationship and stimulate the translocation of photo assimilates, thereby increase the productivity. 
 
Methods: A field experiment was conducted at experimental farm of Agronomy Department, V.N.M.K.V., Parbhani during kharif season of 2018 and 2019. The experiment was laid out in split plot design with four main plot treatments comprised of four crop geometries as 90 cm x 20 cm, 120 cm x 20 cm 60-120 cm x 20 cm and 75-150 cm x 20 cm and sub plot treatments were five treatments on foliar application of plant growth regulators i.e. NAA @ 40 ppm, Mepiquat chloride @ 50 g a.i. ha-1, Brassinosteroids @ 0.1 ppm, Chlormequat Chloride @ 75 g a.i ha-1 and control. 
 
Result: The crop geometry of 120 cm x 20 cm and 75-150 cm x 20 cm recorded higher values of all yield parameters followed by crop geometry of 60-120 cm x 20 cm. While the seed, straw and biological yield of pigeonpea as well as highest net realization of Rs. 72072 ha-1 was obtained with crop geometry of 60-120 cm x 20 cm followed by 90 cm x 20 cm. Among the plant growth regulators foliar application of Brassinosteroids @ 0.1 ppm (G3) tended to recorded higher yield parameters, seed yield and fertility coefficient of pigeonpea as well as highest net realization followed by foliar application of NAA @ 40 ppm.</div>

Production Potential of Pigeon Pea [Cajanus cajan (L.) Millsp.] as Influenced by Crop Geometry and Plant Growth Regulators

<div style="text-align:justify">Background: Intensive cultivation with suitable crop geometry for optimum utilization of resources is one of the possible ways for increasing productivity of pigeonpea. Plant growth regulators have the capacity to stimulate and inhibit physiological processes, which directly or indirectly might affect crop yield and quality. This investigation was planned to study the influence of crop geometry and foliar application of plant growth regulators on production potential of pigeonpea. 
 
Methods: The field experiment was conducted at experimental farm of Agronomy Department, V.N.M.K.V., Parbhani, during kharif season of 2018 and 2019. The experiment was laid out in split plot design with four main plot treatments and five sub plot treatments. The main plot treatments comprised of four crop geometries while thesub plot treatments were five treatments on foliar application of plant growth regulatorsalongwith control.&nbsp; 
 
Result: Various crop geometries shown remarkable effect on growth and developement of pigeonpea. The crop geometry of 60-120 cm &times; 20 cm and 90 cm &times; 20 cm recorded maximum plant height of pigeonpea as compared to other wider crop geometries. While in case of all the other growth attributes viz. number of functional leaves plant-1, leaf area, number of branches plant-1&nbsp;and dry matter accumulation plant-1 crop geometry of 120 cm &times; 20 cm and 75-150 cm &times; 20 cm were found superior as compared to other treatments and were at par with each other. The yield per hectare was increased at closer crop geometry 60-120 cm &times; 20 cm as the lower per plant yield was compensated by higher plant population. The crop geometry 60-120 cm &times; 20 cm produced significantly higher seed yield (1661, 1982 and 1821 kg ha-1 during 2018, 2019 and pooled mean respectively) over crop geometry of 120 cm &times; 20 cm and crop geometry 75-150 cm &times; 20 cm, but it was found at par with crop geometry 90 cm &times; 20 cm. Among the foliar application of plant growth regulators, growth characters viz., plant height, number of functional leaves, leaf area, number of branches and dry matter accumulation plant-1 as well as chlorophyll content were enhanced with the foliar application of Brassinosteroids @ 0.1 ppm and application of NAA @ 40 ppm during both the years of study. Foliar application of Brassinosteroids @ 0.1 ppm also recorded early flower initiation and significantly highest seed yield (1742, 2018 and 1880 kg ha-1 during 2018, 2019 and in pooled data, respectively), while it was at par with foliar application of NAA @ 40 ppm.&nbsp;</div>

&nbsp;​Morphophenological Characters and Productivity of Pigeon Pea [Cajanus cajan (L.) Millsp.] as Influenced by Crop Geometry and Plant Growth Regulators

Background: Robusta coffee leaves regulate gas exchange in response to climatic factors like full sun and shaded conditions. To fully understand the reasons behind the variations in photosynthetic rates and water-use efficiency, exploring the underlying mechanisms of stomatal regulation in the maximum photosynthetic efficiency of Robusta coffee trees, especially in a shade condition is necessary. 
 
Methods: This study aimed to evaluate how stomatal regulation in Robusta coffee leaves affects gas exchange under different cropping systems. The Robusta coffee trees were grown in four different cropping systems: monoculture (full-sun condition) (S1), intercropped (single row) with rubber trees (S2), intercropped (double spacing) with rubber trees (S3), and intercropped in a mixed orchard (S4). 
 
Result: The results revealed that Robusta coffee trees grown between rubber tree rows with closer spacing (S2) exhibited the largest stomata sizes. These stomata sizes had a statistically significant increase in width, length, and area (ranging from 12.04 to 14.74 &micro;m, 19.22 to 25.55 &micro;m, and 202.37 to 296.05 &micro;m&sup2;, respectively) compared to Robusta coffee grown in S1, S3, and S4 systems. On the other hand, Robusta coffee grown in S1 system displayed the highest stomatal density, ranging from 310 to 540 stomata/mm&sup2;. Interestingly, coffee trees grown between rubber rows (S3) and in the mixed orchard (S4) exhibited both high rates of photosynthesis (9.18 and 9.35 &micro;mol/m&sup2;/s) and photosynthetic water-use efficiency (3.78 and 5.15 mmol/mol). Notably, these values were statistically different from those observed in other planting conditions. Additionally, Robusta coffee grown in S1 system exhibited the highest canopy temperature (ranging from 30.8 to 47.4&deg;C). It also had the lowest Fv/Fm value (ranging from 0.706 to 0.759) compared to other planting conditions. This study indicates that Robusta coffee leaves exhibited varying stomatal responses to changes in light and temperature depending on the cropping system. By understanding how these leaf traits influence adaptation, we could potentially optimize Robusta coffee trees to thrive in full sun and shaded conditions, particularly within intercropping systems.

How Cropping System Influences Robusta Coffee Leaf Gas Exchange Efficiency via Stomatal Regulation

Background: Agricultural residues are a significant part of the waste generated in India. It is challenging for farmers to manage surplus crop residue sustainably because of large production and limited options. Ultimately, most farmers burn crop residue without giving it a second thought. Besides affecting the environment, burning crop residues also reduces soil fertility, soil nutrient content and soil organic humus levels by releasing greenhouse gases.&nbsp; 
 
Methods: This study was conducted to identify surplus crop residues available and their current uses. Vidarbha region in Maharashtra was selected for the study and cotton, tur and soybean crops were selected since these are the most commonly grown crops there. A man-to-man survey was conducted to determine the type and amount of crop residue available and how it is currently being used. Three farmlands in the Vidarbha region of Maharashtra were selected for the study. Four different varieties of cotton, tur and soybean were grown on three farms. The yield and crop residue generated were measured per unit area. Analysis of crop residue availability was conducted using statistical methods.&nbsp; 
 
Result: Based on the study, it can be concluded that biomass waste is abundantly available and there is potential to generate bioenergy by utilizing agricultural waste effectively. Furthermore, the regression study shows that crop output is a major predictor of crop residue generated.

A Study of Generation and Regulation of Crop Residue: Bioenergy

Background: The conventional methods of applying water and nutrient results lot of wastage and negatively affect the soil, environment and crop response of pea. 
 
Methods: The experiments were conducted at Lovely Professional University, Punjab during two years. The five drip irrigated treatments having full irrigation, classical deficit irrigation and regulated deficit irrigation in combination same level of nitrogen fetigation @90% recommended dose of nitrogen (RDN) were taken in 4 replications. One control plot (having flood irrigation with soil application of nitrogen @100% RDN through broadcasting) was taken for comparison.&nbsp; 
 
Result: Plant growth, yield contributing parameters, pod yield and water use efficiency (WUE) were significantly affected by drip irrigation in combination with 90% RDN through fetigation over conventional method of irrigation and fertilizer application. Among all the drip irrigated treatments, the increment in crop yield, WUE and irrigation water saving varied from 27.6 to 65.7%, 63.6 to 99.7% and 26.1 to 44.6%, respectively over control plot. In case of same&nbsp; nitrogen fertigation level, the yield and water use efficiency of drip irrigated pea crop can be improved by adoption of moderate water deficit level (which is 15% less than full IWR) under regulated deficit irrigation approach over&nbsp; full irrigation approach. The findings of the work can be utilized by farm managers for irrigation planning and nitrogen management for pea crop and by policy makers to conserve available fresh water resources in water scares regions.

Growth and Yield Response of Pea (Pisum sativum L.) Crop to Classical and Regulated Deficit Irrigation along with Nitrogen Fertilization under Drip Irrigation

<div>Background: Freshwater in sufficient quantity and adequate quality is a prerequisite for human societies and natural ecosystems. To adequately feed 9.3 billion people in 2050, consumptive water use (i.e. transpired water) by all food and fodder crops needs to increase from its present estimated level of 7000 km3/year to 12,586 km3/year. However, fresh water resources are increasingly getting scarce because of increased competition among a multitude of users. Getting agriculture to perform with progressively smaller allocation of renewable water resources will remain a challenge on global scale. To meet the challenge there is an urgent need to improve the crop water productivity to ensure the sustainability of agriculture. 
 
Methods: An experiment was carried out at village Menawali, Hanumangarh, Rajasthan during both kharif and rabi seasons to assess productivity, economics, N-uptake and water use of different crops. An area of 187 ha comprising 25 farmers irrigated by common irrigation channels were selected to collect the information. The information required i.e. soil, crop management, growth, phonological, yields, water balance, N-uptake and water use efficiency of each crops were collected from 15 farmers. Bt-cotton and clusterbean of kharif and wheat and Indian mustard in rabi were prominent crops, cotton-wheat, cotton-mustard, clusterbean-wheat and clusterbean-mustard were major cropping sequences of the study region. 
 
Result: In kharif season, Bt-cotton gave higher economic yields than clusterbean and amongst rabi season crops, economic yields of wheat and mustard were 4255, 1778 kg/ha, respectively. The economic yield of cropping sequences varied from 3741-6514 kg/ha and were higher for cotton-wheat (6218 kg/ha), intermediate for clusterbean-wheat (5785 kg/ha) and lower for cotton-mustard (3741 kg/ha) and clusterbean-mustard (3308 kg/ha). The cotton-wheat (₹1181.2 mm) sequence had highest water use. Clusterbean-wheat cropping system recorded highest water productivity (16.5 kg/ha mm) followed by clusterbean-mustard (14.9 kg/ha mm). The clusterbean-mustard (₹456/ha mm) cropping sequence was most profitable and fetched highest net return followed by clusterbean-wheat (₹383/ha mm).</div>

Assessing Crop and Water Productivity Performance of Different Crops and Cropping Systems

<div style="text-align: justify;">Sulphur dioxide (SO2) and particulate matter (PM) are one of the major air pollutants emerging out of the industrial development and human activities. Plants exhibit differential sensitivity to SO2 pollution and its effects on plant growth can be both direct and/or indirect. We have earlier reported that a high SO2 stress contributes toward the S-nutrition of crops. The SO2 enriched environment significantly improved the activity of serine transacetylase (SAT) in all the experimental crops, however, the activity of O-acetylserine (thiol) lyase (OAS-TL) was enhanced chiefly in wheat but not in chickpea and barley. Further, the relative tolerance of crops to the particulate and gaseous pollutants was related to a lower level of superoxide and H2O2 radicals and lipid peroxidation and a higher level of antioxidants such as ascorbic acid and peroxidase activity. Relative tolerance of crops to the particulate and gaseous pollutants was related to a lower oxidative stress and a higher anti-oxidative defence that elevated SO2 &nbsp;contributes to S-nutrition of crops however, the threshold value of phyto-toxicity need to be determined across the crops.&nbsp;</div>

<div style="text-align: justify;">Crop adaptation to air pollution ii. tolerance to so2 stress is regulated by oxidative and antioxidative characteristics and sulphur assimilation&nbsp;</div>

<div style="text-align: justify;">The impacts on yields of cluster bean were assessed for normal (15 July) and late (30 July) sowing environments and foliar spray of thiourea (500, 1000 ppm) and salicylic acid (50, 100 ppm) at 45 and 60 days after sowing (DAS).Significantly higher yield parameters, yield, economics, protein content and nutrient uptake were recorded with foliar spray of thiourea at 500 ppm as compared to all other bio regulator sprays. Similarly, spray of salicylic acid at 100 ppm enhanced yield and other growth parameters which were statistically at par with those for thiourea 500 ppm foliar spray at 45 and 60 DAS. The data show that the foliar application of bio regulators at normal sowing date enhances seed yield of clusterbean by improving the physiological processes. The interaction effects were significant between the sowing date and bio-regulators on the seed yield. The highest seed yield of 993 and 845 kg/ha was obtained with foliar spray of thiourea at 500 ppm in normal and late sowing, respectively, while the lowest yield &nbsp;of 775 and 769 kg/ha was obtained for the &nbsp;water spray control in normal and &nbsp;late sowing, respectively.</div>

<div style="text-align: justify;">Response of sowing dates and bio regulators on yield of clusterbean under current climate in alley cropping system in eastern U.P., India</div>